THOMAS W. EAGAR: MIT Theses Supervised
(The links
from the thesis titles lead to electronic copies. For theses without electronic
versions, see MIT
Libraries for information on how to obtain them.)
"Mechanical behavior of dip-brazed aluminum sandwich panels," Brian P. Hohmann, Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, supervised by Thomas W. Eagar, pp. 161, 2007.
Abstract:An experimental study
was carried out to determine the mechanical behavior of sandwich panels containing cellular
cores of varying shape. Compression and four point bend tests were performed on sandwich panels with
square and triangular honeycomb
cores. These honeycombs were made of perforated aluminum sheet of repeating diamond and hexagonal
patterns. The sandwich panel assemblies were joined via dip brazing. Defects were introduced into some
panels to quantify the effect on
strength and stiffness. Hybrid sandwich panels, consisting of foam material in the void spaces of the
square and triangular cells were evaluated for the effect on the defect tolerance of the structures. The
results showed that sandwich
panels with diamond shaped cores had compressive strengths approximately four times greater than hexagonal
shaped cores. In four point bending the diamond cores were approximately twice as stiff as cores made from
hexagonal patterned sheet. The
introduction of defects lowered strength by about 30% for diamond cores in compression, and about 15% for
hexagonal cores. In four point bending
this strength reduction was not as significant due to shear stresses
damaging periodicity at a faster
rate than in compression. The use of foam within the cells resulted in higher
absolute peak compression and
flexure loads, however the Load/Density ratios demonstrated cases where
the added weight of the foam did
not result in a better panel. A difference of nearly an order of magnitude between the highest
and lowest compressive and flexure loads
is evident when the presence of defects and foam are taken into account.
"Sintering and joining of low temperature co-fired tungsten and aluminum oxide, " Yuttanant Boonyongmaneerat, Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, supervised by Christopher A. Schuh and Thomas W. Eagar, pp. 189, 2006.
Abstract:Conventional methods used to fabricate co-fired tungsten/alumina composites usually rely on high temperature processing (>1500C). As it would be beneficial or even necessary for some applications to produce such composites at relatively low firing temperatures, low-temperature processing techniques and the attendant knowledge of processing-property relationships need to be developed. In this thesis, a set of experiments and simulations are performed to obtain a better understanding of sintering and joining of the tungsten/alumina system processed at temperatures near or below 12000C. The technique of activated sintering for tungsten is investigated, whereby a minimal content of additives enables low firing temperatures through a change in the sintering mechanism for tungsten. Tungsten compacts produced by this method are found to sinter only to the "initial stage" and are characterized by high residual porosity level. Hardness and fracture toughness of such partially-sintered materials are examined experimentally and analytically, and dependence of mechanical properties on the relative particle neck size is observed. Various studies are carried out to examine both fundamental and practical aspects of joining co-fired tungsten/alumina. First, contributions to adhesion of co-sintered bilayers are studied where the properties of the tungsten layer are controlled using the process of activated sintering. Using a bending delamination test, improvements in sintered density of tungsten are found to increase the adhesive strength of the system only up to a point, beyond which shrinkage mismatch compromises the intrinsic toughness of the interface. A study of low-temperature co-fired tungsten/alumina is then focused on composite shells for an investment casting application. The influences of various processing parameters in a slurry-based route on the sintering and adhesion properties of tungsten/alumina are investigated. Binder content, stucco sand application, and powder characteristics are among the parameters found to critically control the quality of tungsten/alumina shells produced. Finally, the feasibility of several joining strategies, which involve the use of chemical additives, is examined on co-fired tungsten/alumina compacts processed at low temperatures. Some bonding techniques are verified to help improve the bonding of the co-sintered composites.
"Materials production economics : an examination of the variables and relationships that drive materials production and recycling in the world economy, " Yao-Chung King, Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, supervised by Thomas W. Eagar, pp.29, 2006.
"Measurement and control of brake pedal feel quality in automobile manufacturing, " Jeffrey T. Cerilles, Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, supervised by Thomas W. Eagar and Charles H. Fine, pp.60, 2005.
"Improving maintenance work flow processes in a volatile assembly factory environment : maintenance people and processes, spares inventory, and equipment reliability, " H. Ryan Chase, Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, supervised by Thomas W. Eagar and Roy E. Welsch, pp.45, 2005.
"Re-sourcing manufacturing processes in metal forming operations, " Heath M. Holtz, Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, supervised by Thomas W. Eagar and Stephen C. Graves, pp. 76, 2005.
"Beating the system: accelerating commercialization of new materials, " C. S. Musso, Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, supervised by Thomas W. Eagar, 2004.
Abstract: Over the past
century, materials have faced notoriously long delays between invention and
commercialization. These delays make private investment very difficult, and can
prevent good materials from reaching markets. A systematic exploration of the
commercial histories of major commodity thermoplastics was performed, which
showed that these delays were attributable to technical deficiencies in
materials and obstacles in the application value chains. Contrary to popular
wisdom, material costs, competitive materials, and serendipity were much
smaller factors in commercialization delay. The factors that led to insertion
of plastics into applications were different than the factors that led to
post-insertion growth. The major plastics showed a characteristic pattern of
commercialization. First, they entered simple, small applications in which they
solved new problems. They then progressed to achieve insertion in a single
major application, which they continue to dominate today. Having established
themselves with this application, they found insertion in a wide range of large
applications. The commercialization pattern can be explained in large part by
the concept of switching costs. As knowledge of a material increases, switching
costs are reduced; as value chain complexity increases, switching costs
increase. The earliest applications required little understanding of plastics
and had simple value chains, so switching costs were low, corresponding to fast
commercialization. Later applications had more complex value chains and
required much more detailed understanding of the failure modes and processing
parameters of the material, corresponding to high switching costs and slow
commercialization. Materials can be deployed into many markets. By
strategically selecting application markets, materials producers can
significantly improve the probability that new materials will be adopted and
can shorten the period of commercialization. Early markets should be selected
based on the ability of the material to solve unique problems and the
simplicity of the application value chain. When market selection is not an
option, materials producers can integrate forward in the value chain to shorten
commercialization times, but capital requirements are very high. Once
integrated into an application, the safest competitive position for materials
is to be the lowest cost option that meets the exact needs of the application.
"Delivery optimization for a make to order custom wire mill, " Andrey L. Slivinskiy, Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, supervised by Donald Rosenfield and Thomas W. Eagar, pp. 73, 2005.
"Low temperature transient liquid phase bonding of copper, " Joel C. Williams, Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, supervised by Thomas W. Eagar, pp. 34, 2005
Abstract: This thesis
describes a Pb-free solder alternative that is capable of fluxless bonding. The
main advantage of this process is that it offers the benefits of low
fabrication temperature (125¡C) while producing a joint capable of withstanding
low stresses at very high service temperatures (300¡C+). The ternary alloy
system of Bi-In-Sn was investigated in the bonding of copper substrates. All
bonds were made at 125¡C with 25psi of fixturing pressure. Primary
solidification was observed in as little as 15 minutes. The mechanical
properties of the joints were shear tested both at room temperature and at
1000C to simulate a conventional service environment. With sufficient dwell
time (-250h), joints would not fail in shear even at stresses that caused
significant substrate deformation. Scanning electron microscopy was used to
examine the joints and the evolution of the diffusion process.
"Commercial application of aluminum honeycomb and foam in load bearing tubular structures,"Stefano Bartolucci, Thesis (S.M.)--Massachusetts Institute of Technology, Department of Materials Science and Engineering, supervised by Lorna Gibson and Thomas W. Eagar, 2004.
Abstract: Small dimension engineering tubular structures subjected to a complex load system are designed like hollow circular shells. For minimum weight design, the ratio between the shell radius and the thickness has to be as large as possible, but its maximum value is limited by the onset of local buckling. Tubular natural structures subjected to a complex load system have often an outer shell of solid material supported by a low density, compliant core, which makes them more resistant to local buckling. Biomimicking of natural constructions offer the potential to improve the design of small diameter tubular engineering structures. Here, the fabrication technology of biomimicked engineering tubular structures integrating aluminum foam or honeycomb as core material is discussed. A viability analysis is presented including technical performance, cost, utility, and risk assessments. Aluminum compliant core shells have potential for substituting CFRP and aluminum tubular structures in aerospace and high-level sport applications. The case of sailboat masts was considered in detail. Results of our analysis proved that use of honeycomb as core material can lead to a significant reduction of the mast weight. Business opportunities based on this application are discussed.
"Thermodynamics and kinetics of
ceramic/metal interfacial interactions," R. Arroyave, Thesis (Ph. D.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp.248, 2004.
Abstract: Ceramic/metal interfaces occur
in a great number of important applications, such as ceramic/metal composites,
microelectronics packaging, ceramic/metal seals, and so forth. Understanding
the is proposed. Because of the importance of zirconia-based ceramics in
increasingly important applications such as structural composites, thermal
barrier coatings and Solid Oxide Fuel Cells, it was decided to illustrate the
concepts developed in this thesis through the study of the interactions between
zirconias and active metals. Semi-empirical thermodynamic models of all the
phases likely to take part in the ceramic/metal interfacial interactions
studied were developed. Phase diagram data and thermochemical in complex
interfacial reactions occurring during the active metal brazing of
zirconia-based ceramics. By using simple one-dimensional interdiffusion
simulations, it was demonstrated that the base metal in ceramic/metal joints
plays an essential role in determine the thermochemical interactions at the
ceramic/metal interface during ceramic/metal joining operations. In general it
was found that, using all these techniques,it was possible to explain diffusion
paths and reaction sequences observed in a great number of
zirconia/active-metal systems, both in the solid and in the liquid states. In
many cases, the morphology of the reaction layers formed at ceramic/metal
interfaces determine their final properties. To address this problem, empirical
thermodynamic models of the likely reaction products at zirconia/metal
interfaces were coupled to kinetic models using the diffuse-interface
formalism.
"Addressing equipment set-up time and manufacturing
cost through real time inline inspection in tantalum wire manufacturing,"
C. A. Gonzalez, Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan
School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept.
of Mechanical Engineering; in conjunction with the Leaders for Manufacturing
Program at MIT, supervised by Roy E. Welsch and Thomas W. Eagar, pp. 53, 2004
Abstract: For this study, a novel wire
inspection system was developed to detect surface defects and monitor diameter
real-time during the final wire drawing operation. Throughout his work, it was
proven that the new inspection system was able to catch common wire defects
under manufacturing conditions (wire speed). Furthermore, defect density limits
were defined based on data collected during this study. A production version of
the wire inspection system was jointly developed with the equipment supplier
and an order was placed for three complete systems to be installed in all final
draw machines. Increased competition and poor economic conditions forced the
manufacturer to place an unprecedented focus on decreasing manufacturing costs.
The wire inspection system reported in this thesis was developed with the
objective of increasing productivity at the most critical operation in the
factory; final wire drawing.
"Metallographic study of gamma - gamma
prime structure in the Ni-based superalloy GTD111," A. Kountras, Thesis
(S.M..)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, 2004.
Abstract: The potential for land-based
turbine buckets material rejuvenation presents a significant commercial and
scientific interest. Ni-based superalloy GTD111 is used at a number of
GE-manufactured power generation turbines. The outstanding creep resistance
features of Ni-based superalloys can be attributed to a large extent, to the
gamma prime ([gamma]') precipitates found within the FCC [gamma]-matrix.
Service-induced material degradation mainly involves coarsening and shape trans
conditions, leading to useful conclusions concerning material degradation as a
result of high-temperature service exposure. In addition, microstructural trans
GTD111 microstructure. Finally, the measurements were examined for correlation
with existing [gamma]' particle coarsening theory, by calculating and
evaluating the metal service temperature during service. A satisfactory
correlation exists.
"Solving a corrosion quality problem at
a major US automaker," J. C. Wallach, Thesis (M.B.A.)--Massachusetts
Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering; in
conjunction with the Leaders for Manufacturing Program at MIT, supervised by
Thomas W. Eagar and Thomas Roemer, 2004.
Abstract: This project addresses a
corrosion quality problem at an automaker. The problem, hem flange corrosion,
involves the appearance of red rust along edges of closure panels (doors,
hoods, deck lids, etc) after three to four years in service. This project
focuses on finding a solution for a particular new model. The project contains
two parts: a technical treatment of hem flange corrosion and an organizational
analysis. The technical discussion includes a root-cause analysis, failure
analysis of past solution attempts, benefit/cost analysis of potential
solutions, and technical recommendations. The organizational discussion
examines why this automaker was challenged with implementing a solution.
"Smoothing of pipe system completion
processes in a shipyard environment," S. J. Zojwalla, Thesis
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering; and, (M.B.A.)--Massachusetts Institute of Technology, Sloan School
of Management; in conjunction with the Leaders for Manufacturing program at
MIT, supervised by Thomas W. Eagar and Arnold Barnett, 2004.
Abstract: Due to a number of different
production issues, the manufacture of template pipes is often delayed. These
delays hold up pipe system completion on board the ships in production and can
delay payments from the Ministry of Defense. In order to improve the production
of template pipes, a number of changes are recommended to the pipe production
processes overall. These include improvements in production planning, along
with changes in procurement and scheduling methods. These changes in production
methods will result in more material available when it is needed and will
therefore improve the manufacture of template pipes. Additionally, they will improve
the overall availability of pipes when needed as well as reducing inventory of
finished pipes and decreasing the amount of rework. A number of other
recommendations to improve the overall pipe manufacture process are also
identified, including changes in performance measures, production planning, and
other potential areas of improvement.
"Chemistry of airborne particles from
metallurgical processing," N. T. Jenkins, Thesis
(Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar pp. 189, 2003.
Abstract: Airborne particles fall into one
of three size ranges. The nucleation range consists of nanoparticles created
from vapor atom collisions. The decisive parameter for particle size and
composition is the supercooling of the vapor. The accumulation range, which
comprises particles less than 2 micrometers, consists of particles formed from
the collision of smaller primary particles from the nucleation range. The
composition of agglomerates and coalesced particles is the same as the bulk
vapor composition. Coarse particles, the composition of which is determined by
a liquid precursor, are greater than 1 micrometer and solidify from droplets whose
sizes are controlled by surface, viscous, and inertial forces. The relationship
between size and composition of airborne particles could be seen in welding
fume, a typical metallurgical aerosol. This analysis was performed with a
cascade impactor and energy dispersive spectrometry with both scanning electron
microscopy (SEM-EDS) and scanning transmission electron microscopy (STEM-EDS).
Other methods for properly characterizing particles were discussed. In the
analysis, less than 10% of the mass of fume particles for various types of gas
metal arc welding (GMAW) were coarse, while one-third of flux cored arc welding
(FCAW) fume particles were coarse. Coarse particles had a composition closer to
that of the welding electrode than did fine particles. Primary particles were
not homogeneous. Particles larger than the mean free path of the carrier gas
had the same composition as that of the vapor, but for particles 20 to 60
nanometers, smaller particles were more enriched in volatile metals than larger
particles were. This was explained by the cooling path along the bubble point
line of a binary phase diagram. Particles were not necessarily homogenous
internally. Because nanoparticles homogenize quickly, they may form in a
metastable state, but will not remain in that state. In this analysis, the
presence of multiple stable immiscible phases explains this internal
heterogeneity. The knowledge contained herein is important for industries that
depend on the properties of nanoparticles, and for manufacturing, where industrial
hygiene is important because of respirable particle by-products, such as
high-energy-density metallurgical processing.
"Friction stir processing for
superplasticity and other applications," L. B. Johannes, Thesis (M.
Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp. 50, 2003.
Abstract: Friction stir welding is a recent welding technology that
had expanding the capabilities of welding aluminum alloys. From this process,
it was discovered that the microstructural properties of a metal could be
altered with a single pass of the tool, and from this the area of friction stir
processing can be expanded beyond welding. While friction stir processing is a
new field of research, many areas of study have been discovered including the
area of friction stir superplasticity. Using the small grain size achieved by
the process and the high grain boundary misorientation angle, it has been found
that friction stir processing is capable of creating high strain rate
superplasticity in aluminum alloys. This study evaluates the technology of
friction stir processing. In detail, the study examines the applications,
competing technologies, intellectual property, and the start of the business
aspects of the technology. In summary, it was found that the main applications
for the technology are in the automotive and aerospace industries. The largest
competing technology generally uses a six-step process that does not allow for
high strain rates and thick sections. Both of these can be achieved by friction
stir processing. Key patents in the area were also examined. In the business
evaluation it was determined that the technology would likely be applied first
in the automotive industry and used by a major automotive manufacturer in order
to reduce costs. Overall, friction stir superplasticity appears to have a lot
of potential for future superplasticity applications.
"From art to science : improving production
and sales of colored chocolate," C. S. Musso, Thesis (S.M.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering; and,
(M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; in
conjunction with the Leaders for Manufacturing Program at MIT, supervised by
Thomas W. Eagar and Thomas Roemer, pp. 102, 2003.
"Welded repair and maintenance in the
space environment," V. Nikou, Thesis (Nav.E.)--Massachusetts Institute of Technology,
Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology,
Dept. of Materials Science and Engineering, upervised by Koichi Masubuchi,
Patricio F. Mendez and Thomas W. Eagar, pp. 113, 2003.
"Development and manufacture of continuous
strand metal matrix composites," C. S. Musso, Thesis (S.M.)--Massachusetts
Institute of Technology, Engineering Systems Division, Technology and Policy
Program, supervised by Thomas W. Eagar, pp.121, 2002.
"A framework for designing interlayers
for ceramic-to-metal joints," J.-W. Park, Thesis
(Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp. 168, 2002.
Abstract: Engineering ceramics have become
widely used as structural materials due to their excellent mechanical and
thermal properties at high temperature. In most structural applications,
ceramics are integrated as critical components in a system that is largely
metallic and have to be joined frequently to metals. During joining processes,
residual stresses are induced in the joints due to the large differences in
physical properties between ceramics and metals, which degrades the mechanical
integrity of the joints. This thesis proposes improved design rules for
interlayers used to accommodate residual stresses in ceramic-to-metal joints.
Efforts have been made on developing theoretical understanding of the important
factors affecting residual stresses. Using Finite Element Method (FEM)
simulations and Order of Magnitude Scaling (OMS), our understanding could be
summarized and generalized as closed-form analytical equations. In these
equations, the accumulated elastic strain energy in the ceramic has been used
as a more reliable metric for quantifying residual stresses and predicting
failure stress. The equations provide a useful functional relationship between
the strain energy, material properties, and joint geometry. To the best of our
knowledge, they are the first analytical expressions explaining the plasticity
effect in the ceramic-to-metal joints. In these equations, the strain energy
normalized by the scaling factor consisting of dominant parameters is a linear
function of dimensionless groups of secondary important parameters. The
physical implication of each dimensionless group also has been clearly defined.
Based on analytical equations, improved interlayer design rules have been
proposed and verified experimentally. Among the dimensionless groups, 4), the
ratio of CTE difference between the interlayer and each base material,
represents the stress distribution in the interlayer and its effect on plastic
de of an interlayer cannot be modified in practice, the use of additional
interlayers can redistribute the residual stresses in the interlayer and
exploit the ductility of the interlayer more efficiently. Based on this fact,
use of rigid layers with increasing CTE away from the ceramic interface and
insertion of ductile layers between each rigid layer is proposed as a better
multiple interlayer design than multiple interlayers with graded CTE. In the
equations, strain energy increases proportional to the joint radius cubed.
Controlled porosities have been incorporated in the interlayer by patterning to
reduce the joint area, hence to decrease the strain energy. Shear test results
confirmed our design rules for multiple and patterned interlayers. For
patterened interlayers, an optimized level of porosity in the interlayer
without interface weakening could be found. Although the effects of all the
parameters cannot be considered, experimental results confirmed that our
understanding addresses dominant parameters for joint strength with simple
equations that provide a useful viewpoint in designing ceramic-to-metal joints
...
"Manganese and Health in the Welding
Environment," M. C. Balmforth, Thesis (S.M.)-Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering; and,
(S.M.)--Massachusetts Institute of Technology, Engineering Systems Division,
Technology and Policy Program, supervised by Thomas W. Eagar, pp. 95, 2001.
Abstract: There are approximately 0.5
million full-time welders in the U.S., with even more workers welding
intermittently. Over the past thirty years there has been increased interest in
the effects of welding fume on the health of these workers. Manganese is an
essential element in the making of all steel products and steel welding
electrodes and is, therefore, present in fume that is generated during welding
of these materials. Manganese is essential to humans in small amounts, but in
larger amounts it is a neurotoxin and causes manganism, a disease with symptoms
similar to Parkinson's disease. Manganese has been reported to cause adverse
health effects in industries such as paint production, battery production, and
manganese ore mining. Occupational exposure limits for manganese have been
developed based on these industries, and the lowest limit, the TLV"
established by the American Conference of Governmental Industrial Hygienists,
is a source of concern to the welding industry. This thesis attempts to answer
the question, "Is the current exposure limit for manganese feasible and
does it make sense for the welding industry?" It does this by evaluating
whether there is evidence of manganese harm to welders, and evaluating the
issues associated with this topic. Calculations show that during an eight-hour
shift at current acceptable standards, it is not possible for a welder to
ingest enough manganese from the welding environment to cause manganism. There
is also evidence that welding fume, which contains iron as well as manganese,
carries its own antidote to manganism. A hypothesis suggests that manganese in
welding fume, due to affects associated with iron, may not be transferred in
harmful amounts across the blood-brain-barrier (BBB). Economic costs to
industry would be substantial in meeting the lower exposure limit. The evidence
suggests that, at the current permissible level of exposure to total welding
fume, the risk of a welder contracting manganism is essentially zero and the
economic costs that would be involved with the lower TLV@ are not justified.
"Spheroidization of iron powder,"
B. C. Hunsaker, Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of
Materials Science and Engineering; and, (S.M.)--Massachusetts Institute of
Technology, Engineering Systems Division, Technology and Policy Program,
supervised by Thomas W. Eagar, pp. 95, 2001.
"Developing a strategy for change in a
former "mom and pop" job shop," J. Sullivan, Thesis
(M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management;
and, (S.M.)--Massachusetts Institute of Technology, Dept. of Chemical
Engineering; in conjunction with the Leaders for Manufaturing Program at MIT,
Janice A. Klein and Thomas Eagar, pp. 50, 2001.
"Reactive brazing of zirconia to
nickel-based super alloys," R. Arroyave, Thesis (S.M.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp. 98, 2000.
"Using postponement to move from
job-shop to a mixed MRP/job shop environment," T. J. Carroll, Thesis
(M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management;
and, (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science
and Engineering; in conjunction with the Leaders for Manufacturing Program,
Massachusetts Institute of Technology, supervised by Stephen C. Graves and
Thomas W. Eagar, pp. 47, 2000.
"Development of a sampling strategy for
inspecting multi-layer printed circuit boards," M. D. Falcon, Thesis
(S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and,
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, Thomas W. Eagar and Roy E. Welsch, pp. 70, 2000.
"Co-ordinating flows across supply
chains in the low volume gas turbine industry," Miriam Park, Thesis
(S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and,
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering; in conjunction with the Leaders for Manufacturing Program,
Massachusetts Institute of Technology, supervised by Donald B. Rosenfield and
Thomas W. Eagar, pp.80, 2000.
"Repair of partially penetrated weld
joints in copper-nickel seawater piping on naval ships," Alan A. Rechel,
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean
Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of
Materias Science and Engineering, supervised by Thomas W. Eagar and David V.
Burke, p.133, 2000.
"Redefining manufacturing quality
control in the electronics industry," Maureen Fresquez Simington, Thesis
(S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and,
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering; in conjunction with the Leaders for Manufacturing Program,
Massachusetts Institute of Technology, supervised by Thomas W. Eagar and Roy E.
Welsch, pp.104, 2000.
"Definition and implementation of a
visual inventory management system," M. A. Kimber. Thesis
(S.M.)--Massachusetts Institute of Technology, Sloan School of Management; and,
(S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering,
supervised by Stephen C. Graves and Thomas W. Eagar, pp. 71, 1999.
Abstract: Companies today often look to
improved inventory management as a means to lower costs and increase their
ability to consistently meet customer needs. Research was conducted at Alcoa
(Shanghai) Aluminum Products Co., Ltd. (ASAP) in Shanghai, China to determine a
framework that might be used to define and implement a visual inventory
management system in a foil mill, The framework proposed is founded on 1 )
understanding the current material and information flows and developing reasons
why inventory exists, 2) consolidating rolling and annealing schedules,
identifying key specifications, determining necessary inventory levels, and
defining a pull system, and 3) creating an environment where people are
included in the change process and educated in the principles upon which the
visual inventory management system is based, The framework proposed enabled a
pull production system to be implemented at ASAP in the cast shop and rolling
area in approximately 6 months. It is anticipated that total WIP and finished
goods inventory levels will be decreased from 2000T to 1600T, average coil
manufacturing time will be reduced from approximately 19 days to 15.5 days, and
delivery performance will be improved.
"Carbide formation in a nickel-based
superalloy during electron beam solid freeform fabrication," J. E.
Matz, Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, supervised by Thomas W. Eagar, 1999.
Abstract: The Electron Beam Solid Freeform
Fabrication process involves the use of an electron beam to make near-net-shape
metal parts without the need for tooling. Material in wire form is fed into a
melt pool maintained on the surface of the part by the electron beam and a
positioning system causes the deposition to occur in a line-by-line,
layer-by-layer fashion. Solidification occurs at a high rate, forming a fine
dendritic microstructure and fine dispersion of primary carbides. This
structure is believed to be optimal for the manufacture and safe use of certain
nickel-base superalloy parts, notably turbine disks. The growth of carbide
particles from the liquid during EBSFF processing of Alloy 7 18 has been
modeled assuming diffusion control and isolated spherical carbides. The driving
force for growth is assumed to increase in a linear manner throughout the
temperature range of carbide precipitation. The model predicts the maximum
carbide size as a function of EBSFF operating parameters and the alloy niobium
and carbon levels. For the material and conditions used experimentally in this
work, the model predicts a maximum diameter of approximately 1.0 um. The maximum
carbide size will become an important determining factor for turbine disk
performance when oxide and nitride inclusions have been eliminated through
improved melt practices. To illustrate this, the low-cycle fatigue life as a
function of carbide size for a standard specimen geometry was calculated.
Extraction replica transmission electron microscopy of EBSFF samples identified
carbides in the 300-600 nm range, consistent with a population having the
predicted maximum size. Another dispersion of carbides larger than 3 um was
also observed in the EBSFF samples. These are believed to be original carbides
that survived the EBSFF thermal cycle without completely dissolving. More
thorough dissolution can probably be obtained with EBSFF process modifications.
Control material from a conventional vacuum arc remelted ingot with similar
composition was also examined and plate-like carbides up to 40 urn in length
were noted. This is an indication of the enormous potential of the EBSFF
process to refine the carbide morphology and size distribution without the need
for a reduction in carbon content.
"Order of magnitude scaling of complex
engineering problems, and its application to high productivity arc welding,"
P. F. Mendez, Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of
Materials Science and Engineering, supervised by Thomas W. Eagar, p. 195, 1999.
Abstract: This thesis presents the Order
of Magnitude Scaling methodology and uses it to determine the configuration and
dominant forces in the weld pool during high productivity arc welding. This
methodology was developed to consistently address problems for which
experimental and mathematical treatment is difficult, yet the governing
equations and some general characteristics are known. The results generated by
this methodology can be grouped into two sets. One of these consists of
estimations of the unknowns of the problem in the form of power laws. The other
is a set of dimensionless groups that indicates the relative importance of the
driving forces. It is not necessary to solve the original differential
equations, because they are transformed into a significantly simpler set of
algebraic equations. This transformation is possible through the combination of
dimensional analysis and asymptotic considerations. A new condition is
introduced for normalization: that the dimensionless functions vary smoothly.
This essential condition was not considered in previous research. Matrix
algebra is used to provide a systematic treatment for problems involving many
parameters. The application of this technique to high productivity arc welding
determined for the first time that
the dominant force acting on a very depressed weld pool is the arc drag force.
Experimental work in 304 stainless steel was performed to analyze the effect of
the large depression on defect formation. It was found that higher welding
speeds (20% or more) are possible with lower sulfur content (6 ppm vs. 230
ppm). Differences in the size and stability of the weld pool depression are
proposed here as the explanation for this di erence. Steels with lower sulfur
content show a weld pool geometry that tends to decrease the size of the
gouging region (the most depressed part of the weld pool). In higher sulfur
steels, the gouging region tends to extend beyond the hot region of the arc. In
this situation the gouging region freezes prematurely and defects such as
humping or a split bead are generated.
"Impact of scale on performance and
technology in process-intensive industry," J. D. Nystrom, Thesis
(Sc.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp. 116, 1999.
Abstract: Two surveys are performed to
determine production methods, competitive strategies, and scale disadvantages
for a group of small manufacturing plants. Detailed comparisons of economic,
operational, and development activities are presented to identify differences
between industry production standards and small-scale plants. As a group, the
small-scale plants had similar production costs to the standard-scale plants.
The small-scale plants experienced lower average unit fixed costs as a result
of lower capital investment and indirect labor expenses. The small-scale plants
operated closer to their theoretical efficiency levels than the standard-scale
plants. The procedure used to collect and analyze data is referred to as the
direct comparison method. The direct comparison method involves conducting
detailed one-to-one comparisons of production systems at the plant-level. A
pattern of operational trends are reported that contribute to the economic
performance of small-scale plants. The small-scale plants compensated for scale
disadvantages by having greater technology independence, conserving capital,
conducting internal development, and promoting process competence.
"Analysis of a manufacturing and
distribution system," Christopher Chan Ogden, II, Thesis
(M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management;
and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical
Engineering; in conjunction with the Leaders For Manufacturing Program,
supervised by Thomas W. Eagar and Duncan Simester, pp.48, 1999.
"Spheroidization of iron powders by
radiative heat transfer," Rodrigo Javier Quintero de la Garza, Thesis
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of
Mechanical Engineering, supervised by Thomas W. Eagar, pp. 80, 1999.
"Logistics and inventory management for
supporting the customer service function," Dean Harper, Thesis
(M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management;
and, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, supervised by Thomas W. Eagar and Lawrence Wein,
pp.94, 1998.
Abstract: Companies have invested great
effort in recent years to improve profitability via better inventory control
methods. In some instances, this desire of management has translated into the
message that 'inventory is evil'. With this in mind, many companies have
embarked on inventory reduction programs, much to the dismay of many customers.
Coinciding with this company initiative has been a growing body of literature
and academic work that is paving the way. The vast majority of this work has
targeted manufacturing operations with little attention paid to post sale
product support. The Instron Corporation has joined this move towards more
efficient operations having moderate success. The company has attempted, like
many others, to use leading edge materials management methods such as just-in-time
procurement, kanban control systems, and other lean efforts. These
manufacturing initiatives have also been applied to material classified as
'service inventory* that has accumulated over the years and in some cases
decades. The planning for this material, used for maintaining customer's
equipment, has been grossly neglected and the results are stunning. Many
regularly used items are not actively procured, while other parts that are used
very infrequently have built up extremely excessive inventory, This thesis
describes a model that provides a systematic and logical way of planning a
service part inventory that will economically meet customer requirements, The
last section of the thesis is an appendix describing a related issue regarding
product design. Due to reliability and serviceability issues, a product that
tests the material properties of asphalt binder was redesigned to increase
modularity. The design verification process suggested that the new proposal was
sound but brought the testing process itself into question, The maximum stress
and strain values exhibited large variation and several possible explanations
are explored.
"Cost modeling of a manufacturing
process," David Medrow, Thesis (M.S.)--Massachusetts Institute of
Technology, Sloan School of Management; and, Thesis (M.S.)--Massachusetts
Institute of Technology, Dept. of Electrical Engineering and Computer Science,
supervised by Thomas W. Eagar and Stephen C. Graves, pp.49, 1998.
Abstract: A manufacturing firm with a wide
variety of products (or SKUs) faces a substantial challenge when working to
reduce in-process and finished goods inventories. In order to hold less
inventory, production run sizes need to be decreased and the number of changeovers
must increase. As changeovers increase, production capacity is lost and more
labor is spent on nonvalue- added activities. The situation is further
complicated by a difficulty in determining the true capacity of a production
line or a particular piece of equipment. Capacity is affected by downtime,
efficiency and changeovers. In many cases, different types of changeovers can
take place and each type of changeover will have a different completion time.
As companies look to find the optimum inventory levels by comparing holding
costs with manufacturing costs, the variations in capacity and types of
changeovers make it difficult to find the true cost. Manufacturing costs can
rapidly increase if overtime is needed to compensate for additional time spent
on changeovers. Finally, it is difficult to effectively target capital
expenditures and process improvement plans without a clear understanding of the
current capacities and cost structure. This thesis examines a cost modeling
program developed for Tenneco-Automotive (TA). Tenneco's Automotive business
focuses on exhaust and ride control products and has two main groups of
customers: original equipment manufacturers (OEM) such as General Motors and
after-market customers who install or sell replacement parts. The model focuses
on the aftermarket segment since it is more variable and more difficult to
forecast than the OEM business. This variability in the after-market business
has a substantial impact on the manufacturing cost structure. After briefly discussing
the model development process, the majority of the thesis will focus on
applications of the model and Tenneco's plan to use the model to improve its
manufacturing operations. The model is designed to be specific to an individual
plant and has been constructed in a modular format for ease of customization.
Scenarios involving production levels, overtime considerations, changeover
frequency, and capacity planning can be performed for an individual machine or
for an entire manufacturing process, The model determines the cost associated
with each scenario and allows a user to quickly make comparisons between
different production plans.
"Vertical integration and the
portability of skill sets in high tech industries," B. D. Siebach, Thesis
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, and, (S.M.)--Massachusetts Institute of Technology, Sloan School
of Management, supervised by Thomas W. Eagar and Donald B. Rosenfield, pp. 30,
1998.
"Variation reduction in a wafer
fabrication line through inspection optimization, J. W. Bean, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, 1997, and Thesis (M.S.)--Massachusetts Institute of Technology,
Sloan School of Management, supervised by Tom Eagar, Roy Welsch, pp. 52, 1997.
"Thermodynamic data from
multi-component metallic diffusion couples," T. Imai, Thesis (Sc.
D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp. 291, 1997.
Abstract: One of the most important
characteristics of multi-component metallic systems is the free energy
interactions between the solute elements. Much research has been done to measure
these values in multi-component systems, especially in iron based alloys.
However, few measurements have been done successfully in reactive metal systems
such as Ti and Nb alloys. This is mainly because these reactive metals interact
with their container in the liquid state or even in the solid state. A new
method was developed to derive the free energy interaction coefficients of
multicomponent systems from diffusion profiles. While diffusion is inherently a
transient phenomenon and chemical interaction is a thermodynamic property, the
driving force for diffusion is based on the thermodynamic potential difference.
By measuring the diffusion profile in some ternary metal systems, one obtains a
discontinuous diffusion profile, the interfacial values of which can be related
to the activity coefficients. Local thermodynamic equilibrium was confirmed at
the interface, and the free energy interaction coefficients were successfully
derived from chemical compositions at the interface.
"Developing a maintenance strategy : a
case study in an automotive assembly plant," Eunmee Park, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering,supervised by Thomas Eagar, Jan Klein, pp.121, 1997.
Abstract: This thesis examines challenges
in adopting world class maintenance practices. Specifically, it describes
research conducted regarding efforts to enhance the equipment efficiencies
within a mature automotive assembly plant. Although the policy deployment of
other goals and objectives were considered successful, the plant's efforts to
adapt some of the world class maintenance practices did not work so well. As
part of the policy deployment, a preventive maintenance team was formed to
improve up-times of specific equipment. This thesis explores the reasons behind
the difficulties in planning and implementing change in maintenance systems.
This thesis presents recommendations on developing a more effective maintenance
strategy, based on the research and prevalent theory related to cultural
change, project management, team formation and world class maintenance systems.
It also suggests mechanisms available to leadership for cultural change and
describes tools to build commitment towards a shared vision.
"Study of chromium in welding
fume," P. Sreekanthan, Thesis (M.S.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar, pp. 93, 1997.
"Applications of powder interlayers for
large gap joining," Wei-Dong Zhuang, Thesis (Ph.D.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp.214, 1997.
"A framework for determining the
mechanical properties of dissimilar material joints,Ó B. E. Blackwell,
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, supervised by Thomas W. Eagar, pp. 142, 1996.
Abstract: An overview of the various
techniques influencing the performance of dissimilar material joints is
presented. Currently, there is no single analytical model capable of describing
the elastic stresses arising from the interaction of two materials to a change
in temperature. The applicability of continuum techniques is made difficult by
the presence of singularities and the influence of geometry on mechanical
loading. Numerical approaches are not immune to difficulties either. Due to the
influence of singularities, peak stress metrics are very susceptible to the
model formulation within finite element analysis. An alternative metric, based
on strain energy, was shown to offer much higher precision while incorporating
the effect of material properties, joint geometry and bonding temperature. In
the past, many modeling efforts have been limited by the ability to predict and
incorporate realistic mechanical properties which are valid over a wide range
of temperature. Through a combination of deformation mechanism maps and
dislocation mechanics, a material behavior model was developed which is
sensitive to the dominant effects present in dissimilar material joints. The
validity of this approach was evaluated by examining a number of case-studies
and by mechanically testing copper : molybdenum dissimilar material joints
fabricated by vacuum brazing.
"Evolution of the entrepreneurial firm
product strategy and organizational design, ÓJ. B. Burke, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management,
supervised by Rebecca M. Henderson, Thomas Eagar, pp. 136, 1996.
Abstract: This thesis documents the
evolution of organization, technology strategy, and product development at a
rapidly growing, medium-sized firm engaged in the design, manufacture, and
distribution of capital equipment to the electronics industry. It captures
ideas, thought processes, and knowledge developed during a six month Leaders
For Manufacturing Program internship. Perspectives in organization design, the
economics of organization, models of organization, and change theory are
reviewed. We apply these ideas in the context, of the firm. Experiences in
engineering and manufacturing projects with the firm highlight the need for
change. A tiered-team organization, supporting improved business processes, is
created. Preliminary results of the change effort, including the implementation
of a technology and product strategy process, are provided. Finally, we reflect
on the results in light of the problems we set out to resolve and the theories
that shaped our efforts. This thesis documents the application of existing
ideas. It provides some insight into the problems faced by a rapidly growing,
entrepreneurial firm as it transitions into a larger organization.
"Growth of intermetallic phases at low
temperature," C. A. Klepser, Thesis (Sc. D.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar, pp. 138, 1996.
"Organizational learning in a platform
team environment and the development of hard-top doors," C. D. Oates, Thesis
(S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering; and, Thesis (S.M.)--Massachusetts Institute of Technology, Sloan
School of Management, supervised by Thomas W. Eagar and James M. Utterback pp.
98, 1996.
"The influence of cooling rate on the
microstructure of metal alloys," D. A. Penta. Thesis (B.S.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp. 30, 1996.
"Methodology for the synchronization of
material flow in an assembly plant," M. A. Polizzi, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management,
1996, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Mechanical Engineering, Thomas W. Eagar and Donald B. Rosenfield, pp. 60, 1996.
"A constraint based optimization of
manufacturing and sales in the copper tubing industry," J. M. Strimling,
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical
Engineering, 1996, and Thesis (M.S.)--Massachusetts Institute of Technology,
Sloan School of Management, supervised by Thomas W. Eagar, Vien Nguyen, pp. 82,
1996.
"Dynamic electrode forces in gas metal
arc welding," Lawrence Anthony Jones, Thesis (Ph. D.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Jeffrey H. Lang and Thomas W. Eagar, 1996.
Abstract: In gas metal arc welding, a
low-voltage electric-arc plasma is maintained between a work-piece and a wire
electrode, both of which are melted by the arc. This thesis examines the
dynamic forces that affect the detachment of molten metal drops from the
consumable wire electrode. Unlike drops falling from a water faucet, the drops
in gas metal arc welding experience strong magnetic forces generated by the
interaction of the welding current with its own magnetic field. An extensive
set of clear high-speed motion images of metal drops detaching from a welding
electrode was collected under a wide variety of conditions. The images are used
to measure the surface tension of steel as it is found in a gas metal arc
welding plasma. Impulse-response oscillations of pendent molten steel drops are
also measured. A derivation of the magnetic forces acting on necking drops is
performed. Numerical computations of these forces are performed by using shapes
fitted to high-speed images of molten steel drops as they are ejected from the
electrode by magnetic forces during short-duty-cycle current pulsing. A dynamic
model of drop detachment is developed and used to study the competition between
the retaining surface tension force and othei forces (magnetic, gravitational,
and inertial). Simulations performed with this model are compared with
extensive measurements of constant-current welding images and with limited
measurements of pulsedcurrent welding images. The comparisons indicate that the
experimental magnetic forces are much less potent than the calculated magnetic
forces when welding-current transients are not present. A hypothesis is
advanced that internal flows are able to develop under the relatively quiescent
conditions that exist during drop development in constant-current welding. An
apparatus was constructed to axially vibrate the electrode as it is consumed.
Experiments using inertial forces to induce drop detachment are shown.
Comparisons of experimental measurements with simulations performed with the
dynamic drop-detachment model indicate results similar to pulsed-current
welding, namely that magnetic forces are more effective under non-quiescent
conditions, regardless of whether the disturbances are magnetic or mechanical
in origin.
"Options analysis--an innovative tool
for manufacturing decision-making," Craig Spencer Belnap, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management,
1995, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Materials Science & Engineering, supervised by Thomas W. Eagar, James M.
Utterback, pp.123, 1995.
"Process improvements in laser diode
manufacturing : identifying variation and the economics of reducing it,"
Mark Soterios Coggin., Thesis (M.S.)--Massachusetts Institute of Technology,
Sloan School of Management, 1995, and Thesis (M.S.)--Massachusetts Institute of
Technology, Dept. of Materials Science & Engineering, supervised by Thomas
W. Eagar, Vien Nguyen, pp. 181, 1995.
Abstract: Several analyses were undertaken
in an effort to determine how and where variation in the performance of laser
diodes originated. The analyses consisted of quantifying the variation that
existed in the performance of the diodes' threshold current, establishing
correlation between variations in threshold current and other attributes of the
laser diode, and conducting experiments to determine causes of the variation.
Linear and multivariate regression results indicated that the threshold current
performance of the laser diodes was positively correlated to facet
reflectivity. This supports previous theoretical models of the laser diode. The
analyses also indicated that variability in threshold current did not adversely
affect laser reliability. Further experiments showed that the laser diode test
equipment, spatial variation in the wafer, and the bar cleaving process did not
contribute to the variation in threshold current. Analyses of the facet coating
process showed mixed results, indicating that although the coating thickness
was uniform, other attributes of the coating such as stoichiometry may have
caused variations in threshold current. A cost model was also constructed for a
hypothetical manufacturing process. The results showed that the economics of
improving a manufacturing process dictate that total costs will not always be
minimized at higher production yields. This holds true especially if the costs
of improving the processes are high. The results regarding the economics of
process improvement are presented as a series of frameworks and strategic
factors.
"Electron beam (EB)-assisted materials
fabrication," Vivek Ramesh Dave, Thesis (Ph. D.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp.280, 1995.
Abstract: The principal contributions of
this work to the field of electron beam materials processing are fourfold. 1)
Electron beam - based materials fabrication was demonstrated using a wire feed
technique. The experiments demonstrated the successful deposition of 308
stainless steel onto a 304L stainless base. Crack-free deposits in excess of
1.25 cm thickness were deposited. Layered structures consisting of Al-Bronze
deposits on a Monel 400 base were also made. These experiments demonstrate the
feasibility of EB-based SFF (Solid Freeform Fabrication). 2) A new pressureless
technique for the EB-assisted reaction synthesis of aluminide interrnetallics
was developed. This technique allows control over the position of the reaction
front and results in full density and full extent of reaction for such systems
as FeAl and Fe3Al. The technique was successfully applied to the deposition of
fully dense and adherent coatings on steel. 3) Several materials processing
applications were implemented using high energy electron beams (HEEBs). These
include shock surface strengthening, ceramic strengthening, and C/C joining.
The potential benefits of HEEB shock processing in SFF (Solid Freeform
Fabrication) are discussed. This present work represents one of the most
extensive surveys of the applicability of HEEBs to materials processing in
existence. 4) A thermal model was developed to describe the temperature
profiles due to moving distributed volumetric sources. This model takes into
account the volumetric penetration effects of electron beams and extends
existing models for distributed surface sources. The model is applied to
several processing applications and is compared to actual ebeam operating
parameters.
"Selection of operations management methodologies
in disparate cost environments," Mark Richard Kurz, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management, and
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical
Engineering, supervised by Thomas W. Eagar, Donald B. Rosenfield, pp. 86, 1995.
Abstract: Managers are deluged with a
steady stream of operational techniques by academics, consultants, and the
business press. These techniques are merely business tools, but questions can
arise. How does an operations manager choose from the wide variety of tools?
Which tool is most appropriate? This thesis explores these questions in detail
by quantitatively evaluating the strategies of Six Sigma, Theory of
Constraints, The Inventory Solution, and Just-In Time (JIT). The objective of
this thesis is to substantiate the hypothesis that the appropriate operational
strategy depends largely on the cost environment of the business. No single
operational strategy is universally superior. The motivation for this work
stemmed from a fundamental conflict in operational philosophies for an assembly
area at a US manufacturing plant. At the time of this work, industrial
engineering management was considering two distinct operations approaches: the
continuation of a traditional balanced line method, or the intentional switch
to a Theory of Constraints approach. The conflicting messages of these two
techniques around capacity allocation triggered this study. After reviewing the
theories of the four operations strategies mentioned above, this study uses
results from simulation studies to support the hypothesis that no single
operational strategy is universally superior. Several experimental cases are
presented to show that the cost environment of a business will largely influence
the choice of operations strategy. As such, the significance of the
organization's cost accounting system will become quite apparent. The
simulation results provide quantitative support for deciding which operational
technique to adopt. Using both simulation results and organizational analysis
of the assembly operations, this thesis also discusses the benefits of
coordination and synchronization in processes. The behavior that comprises
teamwork requires some investment, but can also generate worthwhile returns.
This thesis applies the results of both the fundamental study on operations
management techniques and the discussion of teamwork to the assembly operations
at a US manufacturing company. Finally, while the operational theories are
useful in describing many systems, this thesis also addresses the shortcoming
of observing problems solely from one framework. Specific problems will often
require tailor-made solutions. This thesis substantiates that no single
operations theory is universally superior. The appropriate method for success
depends largely on the cost environment of the business. Astute managers
recognize the appropriate business tool for their situation and allocate
resources accordingly.
"Surface layer formation on Pb/Sn
alloys," C. S. Lee, Thesis (M.S.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar., pp. 80, 1995.
Abstract: With recent advances in silicon
technology, microprocessor performance is becoming limited by chip-to-package
interconnections. Three primary assembly processes, Wirehonding (WB), Tape
Automated Bonding (TAB) and Controlled Collapsed Chip Connection (C4), are
used. Out of the three assembly processes, this study focuses on C4 technology
where a chip is interconnected to a package by a matrix of solder bumps. C4
offers many advantages over WB or TAB, such as a high input/output density and
better overall electrical performance. Pb/Sn bumps are used as connectors in
the C4 technology. Pb/Sn solder bumps produced by electroplating were
extensively studied. The use of Pb/Sn electroplating process for C4 requires
the ability to etch Ball Limiting Metallurgy (BLM) in the presence of Pb/Sn
bumps. Therefore, the appropriate etchant needs to be selected. Upon etching, a
surface corrosion layer is formed and an appropriate cleaning acid needs to be
selected to remove this layer subsequently. This thesis examines surface layer
formation on solder bumps, the morphology of the surface layer and surface
layer composition. It was found that the morphology of the surface layer formed
on the Pb/Sn Solder bumps is critically dependent on the concentration of the
etchant, especially H2SO4. Using a gravimetric test, XPS and AES analysis, PbO
containing Sn and S, was identified to be the primary component of the surface
layer after the BLM etch. Moreover, the impact of the BLM etch bath on Pb/Sn
solder bumps was investigated. The thickness morphology, composition and the growth
rate of the layer are critically dependent on S from H2SO4. In H202-rich
solution, the surface appears to be loosely packed and the growth rate on the
surface of the bump was found to be reaction-rate limited; whereas, in
H2S04-rich solution, the diffusion rate is the controlling step in forming the
surface layer on the solder bumps. Also, the layer was thin and dense.
Moreover, from the AES scan and the concentration variation of the BLM etch
studies, the optimal concentration was determined to be 86% H2SO4 solution
which results in very slow surface layer growth, limited by the diffusion rate.
Using that concentration, BLM etch rates in vertical and lateral directions
were studied. The overall etch rate in the lateral direction was determined to
be 3 um.min; whereas, the vertical etch rate was about 1.5 um/min, thus the
etch rate is anisotropic. Further research needs to be focused on the BLM etch
rate studies and on developing better methods for measuring thickness and
solubility.
"A manufacturing cell design tool for
the development and evaluation of transfer lines," Scott L. Ransley,
Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of
Management, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Mechanical Engineering, supervised by Thomas W. Eagar, James M. Utterback pp.
100, 1995. Thesis Supervisor .
"Representing troubleshooting
information for a high-volume production line," C. M. Brennan, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management,
1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Electrical Engineering and Computer Science, supervised by Alvin W. Drake,
Thomas W. Eagar, Donald Rosenfield, pp. 75, 1994.
"Application of cellular manufacturing
to low-volume industries," Paul W. Dul, Thesis (M.S.)--Massachusetts
Institute of Technology, Sloan School of Management, 1994, and Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science &
Engineering, supervised by Thomas W. Eagar., pp. 65, 1994.
Abstract: Traditionally, aerospace and
other low-volume manufacturers have structured their operations around process
center layouts. This layout was adopted to cope with the high product mix and low-volumes
with which these companies were faced. Product layouts, with their high levels
of capital investment, were not adopted by low-volume manufacturers due to
their high contribution to unit cost. The key to achieving a product layout
lies in generating sufficient volume over which to distribute capital costs.
Two approaches can be taken to increase volume: (1) design parts such that they
are substantially similar and (2) design manufacturing systems such that they
are flexible enough to produce a wide variety of parts while incurring little
to no set-up time between parts. These two approaches allow economies of scale
and scope to be generated even in low-volume industries. This thesis presents a
case study undertaken at the Boeing Commercial Airplane Group's Renton
Division. It shows how cellular manufacturing can be applied to low-volume
products for substantial gain. The study focuses on the production of doors for
the 737 and 757 aircraft in Renton's Door Responsibility Center (DRC). It
projects that cost savings in excess of 50% are achievable via cellular
manufacturing. It also contends that cellular manufacturing can be extended
across detail part fabrication to attain significant cost reductions throughout
Boeing's product line. While the study points to specific cost reductions, most
of which are precipitated by decreases in labor expense, it also stresses that
their are many less easily quantifiable gains to be made via cellular
manufacturing. These must also be considered when evaluating the merit of
cellular manufacturing projects.
"An automotive lower back seat system
design," William Giacomo Fonte, Thesis (M.S.)--Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering, supervised by Thomas
W. Eagar, pp. 90, 1994.
Abstract: The goal of this work was to
study the effect of different materials used in lower back support systems in
automotive seats. The recyclability of materials used in seat cushions is
presented as well along with the optimization of their design for assembly as
well as disassembly.. Gaining the understanding needed to move forward required
substantial investigative learning up front. The primary vehicles for this were
(1) literature searches, (2) conversing with experts (academic and otherwise)
at the forefront of research and design in the area of seat development, and
(3) contact with existing users of automotive seats. Although some of the
concepts considered were novel, the final concepts represent ideas more in the
mainstream of current seat design practices. One design (the CushAire lumbar
support system) is presented in this report. The CushAire design consists of an
orthopedically shaped inflatable/deflatable composite foam cushion which, when actuated
by the user by depressing a single button, vents air through a single valve
allowing the cushion to take the shape of the individual's lumbar region while
providing uniform support. The design philosophy here was to combine a device
which is capable of providing physiologically correct support with a second
device which can distribute this support dependent upon body type and customer
preference. The CushAire design relies upon a composite foam structure to
provide physically-correct support that is compliant enough to match different
body types. The front layer of foam in the inflatable/deflatable cushion
provides compliance dependent upon body type and individual preference while
the rear cushion provides support for the lumbar region.
"A de-proliferation methodology for
the automotive industry," William Giacomo Fonte, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management,
1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Mechanical Engineering, Thomas W. Eagar, Karl T. Ulrich, pp, 49, 1994.
Abstract: General Motors North American
Truck Platforms (NATP) has identified the need to reduce product complexity
through product de-proliferation as a strategic means to produce higher quality
products at lower cost. This thesis presents a de-proliferation methodology
based on perceived customer values and the impact of product features on
organizational performance. The study addresses both short- and long-term
de-proliferation. In the short term, the focus is on eliminating dysfunctional
variety (i.e., that perceived by the customer as valueless). The long-term
objective is to offer product options that meet customers' desired level of
variety but have a low impact on organizational complexity, thereby maximizing
profits. A case study of a representative de-proliferation of rear axles on
full-size pickup trucks is used to illustrate the process delineated by this
presentation. The rear axle de-proliferation effort at North American Truck
Platforms eliminated 67 of 131 axles. The projected lifecycle savings of
de-proliferating rear axles was estimated to be $82 million. This study offers
a process for extending the de-proliferation of rear axles to all truck components.
"Pilot process development for a medical
diagnostic product," L. Kimball-Zwetchkenbaum, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management,
1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical
Engineering, Donald B. Rosenfield, Thomas W. Eagar, pp.80, 1994.
"The cost of variation and a process
to reduce variation in the assembly of mature aircraft designs,"
Rhonda L. Reynolds, Thesis (M.S.)--Massachusetts Institute of Technology, Dept.
of Mechanical Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of
Technology, Sloan School of Management, supervised by Thomas W. Eagar, Karl T.
Ulrich, pp. 55, 1994.
Abstract: The quality and the price of a
product are two of the main sources of competitive advantage. These in turn are
very dependent upon the production processes used to produce the product.
Variation in the production process is a major source of waste, rework,
non-value-added costs, and lowered quality. The Boeing Company is the world's
leading manufacturer of Commercial jet aircraft. However, this industry is
fiercely competitive, and Boeing will not be able to rest upon its past
laurels. As the cornerstone of Boeing's strategy to maintain its premier
position, the company has committed itself to the continuous improvement of its
products and processes. Reducing and controlling variation in the production
process would greatly contribute to Boeing's goal of cutting waste. lowering
costs, and boosting quality. This thesis documents the author's findings as a
result of a six month internship at The Boeing Company in the Door
Responsibility Center. The following are provided: * A discussion of the
effects of variation on production costs and product quality * A discussion of
Boeing's process to reduce and manage variation on new designs through the use
of key characteristics, as well as the limitations of applying this process to
older designs * An estimate of the costs of variation based on a case study of
shimming and trimming the 757 # 4 Passenger Door * A proposed method for
reducing and controlling variation in the assembly of mature products Variation
in the production process results in rework, which currently accounts for approximately
40% of the direct labor to build an airplane. In the Door Responsibility
Center, the estimated annual cost of shimming and trimming alone is $1.19
million, and these operations account for only a small portion of the rework
resulting from variation in the parts and the assembly process. The use of key
characteristics alone will not solve the variation related production problems.
To correct these problems, an in-depth investigation of the design, the detail
parts and assemblies as-produced, the manufacturing plan, and the tool indexing
plan is required in addition to the identification and measurement of key
characteristics.
"The cause of cellular solidification
structure during transient liquid bonding," Dalero W. Berkeley, Thesis
(B.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.50, 1993.
"Designing measurement systems in a
manufacturing environment," Michael J. Blatz, Thesis
(M.S.)--Massachusetts Institute of Technology, Sloan School of Management, 1993
and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical
Engineering, supervised by Thomas W. Eagar, pp. 61, 1993.
Abstract: In the increasingly complex
world of manufacturing, the ability for an organization's leader to understand
and control the systems by which an organization functions is becoming a
prerequisite for success. In addition to setting a vision, building this vision
into a shared commitment and providing the resources necessary to accomplish
appropriate objectives, the leader must assume this role of designer of the
structures by which the organization functions Such systems may provide
structure for capital budgeting decisions, evaluation and promotion, market
evaluations, or even employee suggestion programs. Systems are the structure by
which we operate. Failure to recognize, understand and control these structures
will bequeath them to chance. The goal of this thesis project was to demonstrate
that a large corporation could benefit from a closer partnership between two
internal divisions. One of these divisions functions as a fabricator and
supplier to the other, a Line of Business involved in office equipment
manufacturing. The existing relationship between these two internal
organizations is strained and uncooperative Management's original intention was
to show that a closer relationship could reap benefits for the company
Consequently, demonstrated benefits would result in the impetus for further
partnering An approach of this manner fails to address the underlying structure
or "system" that is truly causing Ae problem. This thesis examines
the systemic impact of the company's measurement system on the aforementioned
relationship. It demonstrates how the metrics that management uses to evaluate
the performance of three major constituencies inhibits productivity
improvements, places little value on engineering partnerships and costs the
company millions of dollars through poor purchasing decisions. This paper
highlights the underlying structure and proposes a method for creating a new
measurement system that is consistent and supportive of management's
objectives.
"Identifying and reducing the major
components of lead-time in an electronics manufacturing facility," Chad
Jensen Clawson, Thesis (M.S.)--Massachusetts Institute of Technology, Sloan
School of Management, 1993 and Thesis (M.S.)--Massachusetts Institute of
Technology, Dept. of Electrical Engineering and Computer Science, supervised by
Thomas W. Eagar and Charles H. Fine, pp. 135, 1993.
"Shock hardening of 5052 and 6061
aluminum by a high energy electron beam," Mohammad Farnush, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Kennth C. Russell and Thomas W. Eagar, pp. 63, 1993.
"Influence of shielding gas composition
on alloy recovery during gas metal arc welding," Heidi Gibson, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.50, 1993.
"Process monitoring methodologies for
sheet metal assembly operations," Gregory Alan James, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering,
Thomas W. Eagar and James M. Utterback, pp. 137, 1993.
"A systematic approach and framework for
optimizing a polymer sheet manufacturing operation," Jonell Kerkhoff,
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, 1993, and Thesis (M.S.)--Massachusetts Institute of
Technology, Sloan School of Management, supervised by Tom Eagar and James
Utterbac, pp. 106, 1993.
"Hydrogen degradation of high strength
steel weldments," Christos Konstantarakis, Thesis (Ocean.
E.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1993,
and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials
Science & Engineering, supervised by Thomas W. Eagar and Koichi Masubuchi
pp. 43, 1993.
"Measuring customer-driven manufacturing
process improvement in a multidivisional corporation," Jonathan A.
Rennert, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Mechanical Engineering, supervised by Thomas W. Eagar and Stephen C. Graves,
pp. 58, 1993.
"Design of a process development model
focusing on key decision factors for pre-project planning," Mary Ann
Robinson, Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of
Management, supervised by James J. Utterback and Thomas W. Eagar, pp.84, 1993.
"Feasibility of low-temperature
transient liquid phase bonding of TI-6AL-4V alloy," Karl C. Scholoer,
Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, supervised by Thomas W. Eagar, pp. 38, 1993.
"Scheduling employees of a manufacturing
facility," David J. Seitelman, Thesis (M.S.)--Massachusetts Institute of
Technology, Dept. of Mechanical Engineering, supervised by Thomas W. Eagar and
Stephen C. Graves, pp.68, 1993.
"Cost and quality drivers in printed circuit
board assembly," Elizabeth Jane Altman, Thesis (M.S.)--Massachusetts
Institute of Technology, Sloan School of Management, 1992 and
(M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering,
Thomas W. Eagar and Charles H. Fine, pp.67, 1992.
"Building core competencies in auto body
panel stamping through computer simulation," Tracy Lynn Harrison, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, 1992 and Thesis (M.S.)--Sloan School of Management, supervised by
Thomas W. Eagar and James M. Utterback, pp.95, 1992.
"Low temperature transient liquid phase
bonding for electronic packaging," Michelle M. Hou, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.50, 1992.
"Precision laser micromachining of
ceramics," Luciano Spiridigliozzi, Thesis (M.S.)--Massachusetts Institute
of Technology, Sloan School of Management and (M.S.)--Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering, supervised by Thomas
W. Eagar and Stephen C. Graves, pp.50, 1992.
"Analysis of residual stresses in
ceramic/metal braze joints using finite element methods," Charles Bradley
Sweeney, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Materials Science and Engineering, supervised by Thomas W. Eagar, pp.91, 1992.
"Prototyping--paths to the
present," Stephen Hom, Thesis (Mech. E.)--Massachusetts Institute of
Technology, Dept. of Mechanical Engineering, supervised by Thomas W. Eagar and
Stephen C. Graves, pp.126, 1991.
"Joining of 6061 aluminum matrix-ceramic
particle reinforced composites," Russell Klehn, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.77, 1991.
"Improving the strategic contribution of
new technology--learning from a sheet metal FMS," James C. Leonard, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of MEchanical Engineering,
and Sloan School of Management, supervised by Rebecca Henderson and Thomas W.
Eagar, pp.186, 1991.
"The development and implementation of
an improved measuring methodology for aluminum plate," Julia Christine
Putnam, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Materials Science and Engineering, and Massachusetts Institute of Technology,
Sloan School of Management, supervised by Stuart B. Brown, Thomas W. Eagar,
Thomas A. Kochan, pp. 170, 1991.
"Designing a technology policy for
innovation in flat panel displays : overcoming ideology, uncertainty, and
imperfect information to achieve economic growth," Joseph Anthony Raguso,
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, supervised by Thomas Eagar, pp. 174, 1991.
"An investigation of low temperature
transient liquid phase bonding of silver, gold, and copper," John W.
Roman, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials
Science and Engineering, supervised by Thomas W. Eagar, pp.112, 1991.
Abstract: Low temperature transient liquid
phase bonding is a process where metallic bonds are made by soldering at a
temperature of less than 165OC and then holding at that temperature for a
specified time. This process involves the dissolution of the base metals,
silver, gold or copper, into the joining alloy and solidification at the
joining temperature. These bonds can be made resistant to remelting
temperatures much higher than the original bonding temperature. Since these
bonds are formed at low temperatures the stress developed from differential
expansion is minimized. The work reported in this thesis involved investigation
of combinations of the three base metals with each of fifteen solder alloys or
elements. The remelting temperature of bonds produced was determined.
Indications of low temperature transient liquid phase bonding were evident in
the majority of these combinations. Shear strength testing of selected bonds
was performed to measure the strength relative to conventional solder bonds.
Low temperature transient liquid phase bonding may be applicable to the
mounting of temperature or stress sensitive electronic components.
"Use of the design structure matrix in
the improvement of an automobile development process," Michele W.
Sequeira, Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Materials Science and Engineering, and Massachusetts Institute of Technology,
Sloan School of Management, supervised by Thomas W. Eagar, James Utterback,
Steven D. Eppinger, pp.68, 1991.
Abstract: Improving the efficiency of a
process has gained considerable attention, especially in the automobile
industry. While efficiency improvement may be approached from either a task
orientation in which the individual tasks are made more efficient, or from a
systems orientation in which the interrelationships between tasks are improved,
most analysis tools and their solutions are task oriented. The Design Structure
Matrix, in contrast, takes a systems orientation, allowing the entire system to
be considered. It shows, in compact notation, the interrelationships between
tasks. Marks placed in specific places in the matrix show, for each task, from
which tasks inputs are received and which tasks information is supplied to: In
addition, feedback loops which play a significant role in most processes, are
clearly identified through the use of the matrix. Controlling the communication
between the tasks in a feedback loop is vital to the timely and accurate
execution of the process. This analytical tool was applied to the automobile
development process, with concentrated emphasis on the first half of the
process. From this analysis several major feedback loops were identified; two
major loops constituted the first half of the process. Based upon the matrix
and knowledge of the development process, several options for improvement were
formulated. The changes to the system vary from the most radical option of
changing process milestones to simpler changes to individual tasks. In
addition, the tool itself was introduced to the sponsoring company for its
application to subprocesses.
"Impact of manufacturing process and
task designs on work team performance," Augustus Own Tai, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, and Sloan School of Management, supervised by Thomas Kochan,
Thomas W. Eagar, pp.80, 1991.
"Correlations between resistance spot
weldability and thermal contact conductance," Cesar M. Calva, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.80, 1990.
"Issues in new product development--the
introduction of tape automated bonding technology," Virginia Loop Maggs,
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical
Engineering, supervised by Thomas Eagar and Charles Fine, pp.180, 1990.
"Tape automated bonding--product and
process ramp-up," Benjamin R. Samuels, Thesis (M.S.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, 1990, and
Thesis (M.S.)--Massachusetts Institute of Technology, Sloan School of
Management, supervised by Thomas Eagar and Marcie J. Tyre, pp. 133, 1990.
Abstract: Tape automated bonding (TAB) is
currently the fastest-growing electronic packaging technology. It offers
significant lead density advantages over conventional wirebonding and
significant heat dissipation advantages over flip-chip techniques, Motorola,
Inc. and Digital Equipment Corporation selected advanced TAB for the Motorola
chip which drives Digital's new entry into the high-performance computer
market. The materials technologies involved in the TAB development efforts are
leading edge. This thesis details some of the research performed in support of
process development efforts at Motorola's TAB facility. It characterizes yield
variation at Motorola and traces it to specific steps in a vendor's TAB tape
manufacturing process. Motorola and Digital are involved in multiple product
and process rampups in support of Digital's computer. Management literature is
beginning to recognize that the metrics for success in ramp-ups are sometimes
very different from those of a mature technology. Companies which compete in
products with very short life cycles must learn to manage the problem solving
process in environments characterized by high pressure and uncertainty. This
thesis discusses problem solving under those conditions as i t was observed at
Motorola in their TAB ramp-up. It presents new insights into the applicability
of traditional cognitive models of problem solving and offers specific
suggestions for improving the problem solving environment in the Motorola
ramp-up.
"Thermodynamic data from diffusion
couples," Rakesh Rameshchandra Kapoor, Thesis (Sc. D.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp.197. 1989.
Abstract: The goal of this investigation
was to use the information available from a binary metallic diffusion couple to
compute the solution thermodynamics (activity composition relationship) for
isomorphous binary metallic systems. Using a linearly constrained, notlinear
least squares based algorithm that was developed during this investigation, it
is now possible to compute the entire activity - composition curve for
isomorphons binary metallic systems given only the interdiffusion coefficient
as a function of composition (D - c data), and one additional piece of
information such as the measured activity at ONE particular composition or the
slope of the Henry's law line at infinite dilution. The Inherent non uniqueness
of the problem leads to multiple solutions on an activity-composition diagram.
The single additional piece of information (the measured activity at one
composition or the Henry's law line) is used in selecting the correct solution
from the set of possible solutions, The algorlthm was applied to ten
isomorphous binary metallic systems for which data on the chemlcal
interdiffusion coefficient as a function of composition was obtained from the
literature, For eight out of the ten systems the algorithm located a solution
that either matched the experimental data reported In the literature or
exhibited a trend very similar to it. There is no experimental data for one
additional system and for another system the predicted activities did not match
the measured activities. The algorithm may be easily extended to systems
containing a miscibility gap. The algorithm represents a new technique for
obtaining thermodynamic data from a source that has previously never been used
to generate thermodynamic information, namely a diffusion couple. It should be
particularly useful for reactive and refractory metal systems for which there
is currently a paucity of thermodynamic data caused by experimental
difficulties. It will also check the consistency between the available data on
interdiffusion coefficients and the activity data.
"Analyses of resistance spot welding
lobe curve," Euiwhan Kim, Thesis (Sc. D.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar, pp. 301, 1989.
"Metal transfer in gas metal arc
welding," Yong-Seog Kim, Thesis (Ph. D.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar, pp. 294, 1989.
Abstract: This investigation explores the
effects of welding parameters on metal transfer phenomena in Gas Metal Arc
Welding (GMAW). The welding parameters studied include welding current,
shielding gas composition, welding material, and electrode extension. Droplet
sizes were measured for steel, aluminium, and titanium electrodes by high speed
videography and compared with predicted droplet sizes predicted by the static
force balance theory and the pinch instability theory. The comparison shows
that the droplet size predicted from the static force balance theory can
predict the droplet size reasonably well in the range of globular transfer, but
deviates significantly in the range of spray transfer. The cause of the
deviation was found to be due to tapering of the electrode tip during welding.
Heat transfer mechanisms in the electrode were studied in order to couple metal
transfer with heat transfer. Electrode melting rates were measured as a
function of the welding parameters and fitted into the qudratic function
proposed by previous investigators. The coefficients of the quadratic function
were compared with coefficients calculated from energy conservation theory to
evaluate the validity of this theory for modeling electrode melting. It is
found that the previously proposed theory is inadequate to explain electrodc
melting behavior. Using a more complete temperature distribution model of the
electrode, a new energy balance analysis was developed. This new model
included: joule heat, condensation heat, and heat input through the
liquid-solid interface. The rate controlling step for heat transfer through the
liquid-solid interface was found to be conduction transfer at the interface.
based on this energy balance analysis, a new model of electrode melting was
proposed, which agrees witht the experimentally measured melthing rates.
Combining the resuts of the droplet size prediction from the static force
balance theory and the electrode melting rate measurements, a new theory of
pulsed current GMAW is proposed. A theoretical pulsing frequency is predicted
by this new theory. For given pulse parameters, experimental results show that
there is a range of optimum pulsing freqquency and that this optimum pulsing
frequency can be predicted using the theoretical pulsing frequency and natural
drop transfer frequency. The pulsing parameters were also varied to investigate
the effect of tapering of the electrode on the droplet size in pulsed current
welding. The results are used to prove the validity of the static force balance
theory in modeling the droplet size in pulsed current GMAW.
"Submerged arc welding consumables for
HSLA-100 steel," Daniel Joseph Peters, Thesis (Nav. E.)--Massachusetts
Institute of Technology, Dept. of Ocean Engineering, 1989 and Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering
and Computer Science, supervised by Thomas W. Eagar, pp.122, 1989.
"The effect of nitrogen and titanium on
the toughness of high strength saw weld deposits," Stephen W. Stanko,
Thesis (Nav. E.)--Massachusetts Institute of Technology, Dept. of Ocean
Engineering, 1989 and Thesis (M.S.)--Massachusetts Institute of Technology, Dept.
of Materials Science and Engineering, supervised by Thomas W. Eagar, pp. 158,
1989.
"Gas-metal arc welding in pure
argon," Stephen Theodore Eickhoff, Thesis. (M.S.)--Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering, supervised by Thomas
W. Eagar, pp. 130, 1988.
"The influence of cooling rate on the
microstructure of stainless steel alloys," John Walter Elmer, Thesis
(Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp. 388, 1988.
Abstract: The emergence of high energy
density welding, laser surface modification and rapid solidification as
commonly used metallurgical processing techniques has greatly increased the
range of cooling rates that can be accessed during the solidification of metals
and alloys. The microstructures which develop during these rapid cooling
conditions may be significantly different from those which develop during low
cooling rate conditions as the result of access to new metastable phases with
the additional kinetic limitations that accompany rapid solidification. This
investigation explores the influence of cooling rate on a series of seven
ternary alloys which span the line of two-fold saturation in the Fe-Ni-Cr
system. High speed electron beam surface melting was used to resolidify these
alloys at scan speeds up to 5 m/s. The resulting cooling rates were estimated
from dendrite arm spacing measurements and were confirmed by heat flow modeling
to vary from 7x100 åÁC/ to 8x106 oC/s. The microstructures that developed from
each solidification condition were examined using optical metallography,
electron microprobe analysis, scanning electron microscopy and a vibrating
sample magnetometer. These results were used to create diagrams to predict the
primary mcde of solidification, the ferrite content and the complex
microstructural morphologies which develop as a function of interface velocity
and composition. Changes in the primary mode of solidification with increasing
cooling rate were observed in alloys that lie close to the line of two-fold
saturation. The thermodynamics and kinetics of solidification were used to
explain these changes by showing how epitaxially grown metastable phases can
dominate solidification at high cooling rates, without the necessity of
postulating the nucleation of metastable phases within the melt. The influence
of cooling rate on interface stability and solidification segregation was
evaluated by calculating the solutal diffusional characteristics at the tip of
columnar dendrites growing under steady state conditions. These calculations
were used to predict the dendrite tip undercooling for e-ch solidification
condition and the results were used to evaluate the influence of cooling rate
on the amount of second phase formation, the ferrite content, and the absence
of second phases at high cooling rates. The solid state transformation of
ferrite during the cooling of the resolidified Fe-Ni-Cr alloys was shown to be
analogous to the decomposition of austenite in Fe-C alloys. Parallels were
drawn between these two systems which allowed a wealth of analysis performed on
the Fe-C system to be applied to the Fe-Ni-Cr system. The influence of cooling
rate on the nucleation and growth kinetics of austenite was then used to
explain the conditions which are responsible for the formation of grain
boundary allotriomorphs, Widmanstatten platelets, Widmanstatten needles and
massive austenite grains in the resolidified electron beam melts.
"Non-destructive techniques for
inspection of arc spot welds," Karen Tweed Hays, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering,
1988, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of
Materials Science and Engineering, supervised by Thomas W. Eagar, pp. 266,
1988.
"Non-contact temperature
measurement," Mansoor Ali Khan, Thesis (Sc. D.)--Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering, supervised by Thomas
W. Eagar, pp. 100, 1988.
"Welding flux binders produced by
sol-gel processing," Jon David Kryscnski, Thesis (M.S.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp.81, 1988.
"Non-uniform current distribution in
spot welding," Randy Joel Bowers, Thesis (M.S.)--Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering, supervised by Thomas
W. Eagar, pp. 70, 1987.
"Hydrogen assisted cracking of high
strength steel welds," Steven Anthony Gedeon, Thesis (Ph.
D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp. 361, 1987.
Abstract: Material and process parameters
which affect the lobe width of galvanized steel sheet have been evaluated.
Mechanisms of weld nugget formation have a l s o been investigated with the aid
of dynamic inspection monitoring of the resistance and displacement. It has
been found that hot-dipped galvanized coatings have a wider range of acceptable
welding conditions than the commercial galvannealed products, due to the Fe-Zn
intermetallic morphology and coating composition. Small variations in thickness
of the hot-dipped coatings seem to have a minimal effect on the welding range.
Surface roughness was shown to have no effect on lobe width. Upsloping and
downsloping of the weld current increases the welding range of hot-dipped
products when using truncated cone electrodes, whereas sloped current has shown
no advantage for the galvannealed or uncoated materials. Radiused electrodes
can increase the lobe width of hot-dipped products but are not beneficial when
using sloped current or when welding galvannealed or uncoated materials. Preheating
seems to have the same effect on lobe width as upsloping. Dynamic inspection
monitoring can be useful for understanding and following the progression of
weld nugget formation, but has not been entirely satisfactory to date for
quality control monitoring.
"Brazing
alloys for ceramic to metal joining," Rakesh R. Kapoor, Thesis
(M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.208, 1987.
Abstract: The poor flow of conventional brazing
alloys on ceramic materials necessitates addition of reactive metals that
promote flow by decomposing a thin surface layer of the ceramic. The design
philosophy behind such alloys is presented here. Several experimental alloys
were prepared by arc melting under a protective argon atmosphere. These were
tested for wettability on Si N at 9 5 0 ~ . The contact angle setup used was
fabricated during this investigation. Some of the wetted samples were sliced
and examined metallographically using optical microscopy, scanning electron
microscopy and electron microprobe techniques. The results indicate that
reactive metal additions of Ti and Zr to conventional brazing alloys promote
flow over Si N . Of the two, Ti is the 3 more potent reactive metal. Alloys
that flowed well (contact angle less than 15') were: (i) Cu-80%,Sn-10%,Ti-10%
(ii) Cu-70%,Sn-20%,Ti-10% (iii) Ag-Cu eutectic + 5% Ti (iv) Ag-Cu eutectic +
5%Zr. Of these, the first three had been reported by earlier investigators
while the fourth is a novel brazing alloy, No conclusive correlation was found
between the thickness of the intermetallic layer and the wetting behavior,
"Slag detachability from submerged arc
welds," Adebisi Oladimeji Oladipupo, Thesis (Sc. D.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, p. 206, 1987.
Abstract: Over fifty percent (50%) of the
total steel weld metal is deposited by one of the flux-shielded processes. Slag
adherence to the weld metal surface is one of the major factors controlling the
usefulness of these processes. Slag attachment to the weld metal, especially in
a multipass welding, can severely degrade the weld metal properties. Hence, any
improvement in the welding flux technology that eases slag detachability will
be applicable to both a wide range of industries and a wide range of welding
processes. Some fluxes provide slags of poor detachability with certain
electrodes and/or base metal while the same fluxes provide slags of easy
detachability with other electrode-base metal combinations. On the other hand,
changing of the process parameters (e.g. cooling rate) alone has been observed
to affect detachability. In the cases of adherent slags, what are the
mechanisms of adherence? In order to understand the mechanics of this adherence
and identify the major factors affecting detachability, the physiochemical
properties of the flux, electrode and base plates were studied . Chromium, and
chromium oxide were found to affect the detachability of welding slags. Several
welds were made with stainless steel electrodes (26.27 wt%Cr), chromium
oxide-rich flux and some deposited with mild steel electrodes (no chromium) on
chromium-containing base metals. Examination of the weld metal surfaces, after
the slag had been detached, by scanning electron microscopy showed the presence
of faceted slag particles of high melting temperature which formed during
slag-metal reaction and attached in the solidifying weld metal. X-ray
diffraction analyses showed these particles to be chromium spinels (iron
chromate, magnesium-aluminumm chromate). These particles have a melting
temperature in excess of 1600 C. On the other hand, titanium oxide's
detrimental effect on slag detachability was due to the formation of high
melting temperature (> 1900 C) perovskites (calcium titanate) that also
attach to the solidifying weld metal. The irregular interfaces formed by these
solid reaction products then provide regions into which the molten slag
solidifies and mechanically interlocks resulting in poor slag detachability.
The effects of base metal composition and the surface condition of the base
metal were also studied and found to affect the detachability of slag both
physically and chemically. When changing from steel base metal to a
nickel-based alloy, detachability worsened significantly. This effect was
related to the presence of chromium in the nickel-based alloy (16 wt% Cr)
compared with the steel base metal (1.35 wt% Cr) which results in a chemical
effect because of the formation of chromium spinels as reaction products as
noted above. However, when comparing different steel base metals with little or
no chromium the difference in slag detachability was attributed to the base
metals' thermal contraction characteristics. The experimental observations on
detachability and the results of dilatometric measurements confirmed that the
use of absolute values of the coefficients of thermal expansion of slag and
base metal to determine which flux composition will provide easy detachability
can be erroneous. The mean integrated differential thermal contraction of the
slag-metal systems were evaluated from the softening temperature of the slag to
30 C. A comparison of the detachability of slags from welds made on mild steel
(1010 steel) base metal and HY80 base metal (quenched and tempered martensitic
steel) showed that the integrated differential thermal contraction per unit
length was smaller with mild steel base metal than with HY80 base metal and
that the slags of corresponding welds were more difficult to detach in the case
of the mild steel base metal. This correlation of integrated differential
thermal contraction per unit length with detachability was found to be valid
only in the cases of slags with microcrack-free structures. Furthermore, the
cooling rate of the slag-metal system has an effect on the detachability. The
higher the cooling rate, the poorer the detachability. The surface condition of
the base metal, that is whether descaled or scaled, was found to affect the
detachability of the slag. Scaled base metal provided slags that were more
difficult to detach than the slags from a thoroughly descaled base metal under
the same conditions of welding. This deleterious effect was attributed to the
formation of a chemical bond when the molten slag dissolves the scale and forms
a glass. Also, the presence of scale will increase the oxidizing potential of
the slag making it easier to oxidize deleterious elements like chromium in the
base metal (even when the base metal is low in chromium). The general findings
of this work show that chemical effects due to slag-metal reactions are more
important than physical effects of differential thermal expansion. However, in
the absence of chemical effects the differential thermal contraction
(expansion) is a more useful indicator of ease of detachability than the
absolute value of the coefficient of thermal expansion of the slag or weld
metal. Also, the correlation of differential thermal contraction with
detachability of slag has to be done with the knowledge of the structure of the
slags in question. Finally, the chemical composition of the base metal and its
surface condition are also important factors that affect the degree of slag
detachability.
"Visible light emission during gas
tungsten arc welding," Euiwhan Kim, Thesis (M.S.)--Massachusetts Institute
of Technology, Dept. of Materials Science and Engineering, supervised by Thomsa
W. Eagar, pp.131, 1986.
"A study of the wetting of alumina by
silver-based active metal braze alloys," Edward Scott Podszus, Thesis
(B.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering,
supervised by Thomas W. Eagar, pp.71, 1986.
"Transport processes affecting the shape
of arc welds," Min-Long Lin, Thesis (Ph. D.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar, pp.188, 1985.
"Digital signal processing as a
diagnostic tool for gas tungsten arc welding," Carl David Sorensen, Thesis
(Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and
Engineering, supervised by Thomas W. Eagar, pp.167, 1985.
"Metal vapors in gas tungsten welding
arcs," Gregory Joseph Dunn, Thesis (M.S.)--Massachusetts Institute of
Technology, Dept. of Materials Science and Engineering, supervised by Thomas W.
Eagar, pp.196, 1984.
"Resistance spot welding of galvanized
steel sheet," Steven Anthony Gedeon, Thesis (M.S.)--Massachusetts
Institute of Technology, Dept. of Materials Science and Engineering, supervised
by Thomas W. Eagar, pp.253, 1984.
Abstract: Methods of measuring the
hydrogen content of Gas Metal Arc Welds (GMAW) are evaluated. The recently
developed American Welding Society standard A4.3-86 using gas chromatography
was found to measure the relevant content with reasonable reproducibility,
whereas the IIW specification does not. The amount of hydrogen absorbed by Gas
Metal Arc Welds as a function of percent H20, O2 and CO2 added to the argon
weld shielding gas is quantified. Sievert's law is shown to be invalid for
modeling the amount of hydrogen initially absorbed by the molten weld pool. A
new model is postulated based on the hypothesis that diatomic hydrogen will
dissociate in the cathode boundary layer at a different reaction temperature
than the hydrogen absorption
reaction which occurs at the temperat