21COE, University of Tokyo

MMRC Discussion Paper No. 169

MMRC
DISCUSSION PAPER SERIES

MMRC-F-169

Production Engineering as System Integrator?
A Research Note based on a Study of DoorEngineering and Assembly at Toyota Motor
Corporation
Massachusetts Institute of Technology
Daniel E. Whitney
Yokohama National University
Daniel A. Heller
The University of Tokyo
Hidetada Higashi
The University of Tokyo
Mitsuhiro Fukuzawa
June 2007

Production Engineering as System Integrator?
A Research Note based on a Study of DoorEngineering and Assembly at Toyota Motor
Corporation
Daniel E. Whitney (Massachusetts Institute of Technology)
Daniel A. Heller (Yokohama National University)
Hidetada Higashi (The University of Tokyo)
Mitsuhiro Fukuzawa (The University of Tokyo)
June 2007
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Discussion Paper
Manufacturing Management Research Center (MMRC)The University of Tokyo

I. Introduction
Toyota has been of interest to academic researchers for many years due toits interesting methods of manufacturing and management of productdevelopment. Among researchers whose work is cited in this research note
are Fujimoto, Hino, Liker, Morgan, Spear, and Sobek. For the purpose of thisresearch note, Toyota is viewed as interesting for several related reasons:
1. Toyota appears from the outside to be very good at what in theaerospace industry is called System Engineering. The main effect of thisapproach to product development in an automobile company is a focus on
systems (collections of parts that perform important functions) rather than on
the individual parts. In some car companies, it seems that there is a belief
that good parts will make a good car. Attention to systems requires somedefinite fraction of the employees, perhaps 5%, to be willing to look beyond
their immediate area to find out about related items and activities.
2. Toyota has carefully chosen what to outsource and what to keep inhouse. By Whitney’s past observations, items requiring high technology or
technical skill, either in the car or in the manufacturing process, are typically
kept in-house. In many car companies, much of the technically challenging
items or tasks are outsourced, leading to dependence on suppliers [Fine andWhitney]. These suppliers are very good at what they do but often cannot
integrate what they do with what the car company and other suppliers do.
3. Toyota does not seem to reach for the most advanced technology
available to or used by the car industry in general, either in design software or
factory equipment, but tends to stay a bit behind in favor of relative simplicity.
1This document is a translation of an April 2007 Japanese language discussion
paper (#2007-MMRC-160) available at <<http://www.ut-mmrc.jp>>.
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The result is methods that look less capable to other car companies but which
the average engineer or shop floor veteran can carry out without the need for(usually scarce) experts.
Whitney’s research on the design processes for car doors has shown thatdoors are complex systems in themselves, containing nearly all the elementsof a car except the power train: exterior styling, interior styling, glass, paint,
operating mechanisms, safety, entertainment, and climate control [Whitney a].
Other than seats and the instrument panel, the customer interacts with thedoor more than with any other part of the car, albeit intermittently.
Doors are complex not only because they contain many technicalcomponents but also because they need to be designed to deliver a number of“attributes” of direct interest to the customer. Apart from safety, the mostimportant of these are closing effort, wind noise, water leakage, and fit andfinish (also called gaps and flushness). Designing a door to meet strict
targets in each of these domains is difficult enough, but the problem iscomplicated by the fact that the attributes interact and/or and conflict witheach other. In particular, better sealing to keep out noise and water will
make closing the door more difficult. Predicting analytically how a door will
behave in these domains before the door and car body exist is also difficult.
If it is found that prototype vehicles do not meet the targets, delays can occur
while the designs and associated stamping dies and other tools and fixtures
are revised.
The main goal of the study on which this research note is based was tolearn how Toyota addresses door design at a system and attribute level inboth design and assembly and to see what outsourcing decisions Toyota has
made. The authors have all visited many auto companies and plants. In
1991, Whitney visited Toyota in Japan among many companies in manyindustries [Whitney b] [Whitney c].
In general, what was learned on this study reinforced many things that are
already known about how Toyota approaches product development, butmany details were enriched with examples, especially related to doors.
Morgan’s PhD thesis, completed in June 2002, explains the main timelines ofToyota’s development process as well as the way sheet metal parts and dies
are designed and the essential role of Production Engineering in this processfrom the styling stage onwards. The PhD thesis of Sobek shows how Toyota
values system thinking and promotes people who are good at it. The bookby Hino explains how standardized processes were at the heart of Toyota’s
operating principles at the beginning of the company in the 1930s. This
study confirmed that all of these practices are still in place in 2007.

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II. Study Outline
In 2004 Whitney visited the body shop and final assembly line of Toyota’s
plant in Georgetown, Kentucky, and was able to observe door welding andassembly of unpainted doors as well as attachment of these doors to
unpainted bodies and final adjustment of door fit near the end of the final
assembly line. Consistent with this prior visit, the authors sought but were
not permitted to tour the unpainted door assembly area in the body shop on
this visit. Instead we were allowed to tour the re-spot welding line and final
assembly area of Line #1 at the Motomachi plant. We saw painted doors
receiving all their additional parts such as latches, glass, seals, and interior
trim. The main point of interest during this tour is the fact that eight2
different car models , including minivans, sedans, and station wagons, aremade on the same re-spot line and the same final assembly line. The rest of
the visit comprised interesting discussions with managers and engineers ofthe door design and production engineering processes. The visit comprised
about 9 hours spread over two days.
Our hosts from Production Engineering included Mr. O. (a highly
respected senior manager in Production Engineering (PE) Planning), Mr. I.
(also in PE Planning), Mr. Sa. (General Manager of the Vehicle Planning and
Production Engineering Department within Vehicle Production Engineering),
Mr. Su. (a Group Manager in the Interior/Exterior (I/E) Production
Engineering Planning Division responsible for door PE ), Mr. Um. (ProjectManager for doors for one car program in the Interior/Exterior Production
Engineering Planning Division, and Mr. G. (a new young engineer in Mr.
Um.’s group who works in Europe but is in Japan for training). Our hosts
from door design engineering were Mr. Ue. and Mr. Y., both from the Lexus
product development center.

III.Design and Manufacture of Doors
A. The Role of Design Standards and Standard Design
Procedures
One of the key features of product development at Toyota is the speedwith which it can convert the Chief Engineer’s concept into cars coming off
the assembly line. While all car companies are doing this faster, Toyota
seems to be faster than most. At the same time, quality has not suffered.
The methods used to design doors share characteristics with the rest of
Toyota’s product development process. These have been discussed at length2

The model names are: Crown, Crown Majesta, Crown Estate, Mark X, Estima,
Mark II Blit, Progres, Brevis. If the Crown Athlete/Royal is considered aseparate model then the number of models would be nine.
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by Fujimoto, Sobek, Morgan, and Hino, among others. Among the key
features of the process are
•
•
•
•

•

•

•

Standardized processes and designs
A limited menu of choices for key components and metal materials
and shapes, other than exterior styling shapes
Close interaction between production, PE and design, including
styling
Highly skilled engineers and technically strong managers, all ofwhom spend 4 to 6 years in a given job before moving to anotherone
Great depth of experimental knowledge about door (or othersystem) behavior, correlated with the menu choices so that there islimited uncertainty about how the door will behave before any
prototypes are built to reduce or eliminate re-work
Embodiment of the knowledge, data, design methods, and menu
choices in thick books of standards and design process
requirements
Rigorous updating of these standards whenever a discrepancy isfound between design expectations and actual behavior

As a result, there are, for example, few basic kinds of door architecturesand only a few types of hinges, rear-view mirrors, and handles. There arealso just a few types of door frames and they differ only in exterior
appearance. Furthermore, ways have been developed whereby designers
can estimate the effects of design changes, such as what the effect will be on
closing effort, for example, if an additional seal is added or the seals aredesigned to compress more.
The reasons for approaching door (and other domain) design this way
include avoiding proliferation of designs and methods, encouragement oflong term learning about the chosen designs, avoidance of time-consuming
surprises during prototype builds, and improvement in engineering
personnel’s skills without wasted effort. In addition, with as many as 10 car
programs ongoing at the same time, there is no way the existing staff ofdesign and production engineers could carry the workload if they did notwork from standard designs whose behavior is basically known already.
The accumulated knowledge extends well beyond how the doors will behave
in use and include the most productive ways to build them in the factory.
Typically, in the design of a complex system with conflicting goals, a lot oftime is spent trading off one attribute for another, including goals for Designfor Manufacture and Design for Assembly (DFM and DFA). Apparently
these tradeoffs were made 5 to 10 years ago when today’s standards andselected architectures were being established. According to the interviewees,
there are now few surprises during prototype builds because the basic

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designs and manufacturing methods tend to change so little from one year to
the next.
As described by Hino and reinforced during this visit, the standards areprotected in two ways. First, major changes are controlled by committees
headed by senior executives, and changes are rare. Second, any time a
discrepancy is found between predictions and behavior, the standards are
updated. Additional learning is protected and encouraged down the supply
chain because approved parts tend to be used across car programs, and thistends to entrench incumbent suppliers, giving them ample opportunity to
improve their quality.
The calculations that support engineers appear to be basic curve fits or
first principles formulations, such as the energy dissipated when a door closes.
Complex CAE may be available but such methods are not used every day byengineers. This approach seems consistent with what Whitney observed
during his 1991 visit where he was shown simple but effective methods forevaluating stamping feasibility. No CAE was involved. Other carcompanies used much more sophisticated methods but Toyota emphasizedthat regular engineers could use their methods and trusted them because they
were easy to understand. Also, Toyota has a specialist department called
Evaluation, which contains a few engineers who are experts in closing effort,
seal behavior, and so on. These people serve all the ongoing car programsand do detailed calculations or experiments when the standard calculations
are either not sufficient or else a somewhat different design is being used that
goes beyond the predictive power of the standards. Whitney guesses thattoday Toyota uses lots of sophisticated CAE to aid stamping evaluation but
not on an everyday basis because the standards protect the designers fromserious mistakes.
Mr Ue. was among many who said that Toyota’s current procedures,standards and levels of predictability in door design stem from efforts begunin the mid 1990s. Yet Hino says that the tradition of running the company
from standards dates to the 1930s. (A later section of this research note
discusses this point in more detail.) From about 1995 to 2000, lots of effort
went into revising these standards and knowledge bases for door design.
Since 2000, the knowledge has been used and updated incrementally but not
substantially changed. Some areas of knowledge comprise 20 or more yearsof accumulated experiments and evaluations on actual car programs, so theperiod from 1995 to 2000 represents a resurgence of an established method
rather than a new approach.

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B. The Door Design Process
1. Methods
As described by Morgan, the design process contains multiple main
evaluation iterations of the design before the CAD data are released to the die
production shops. An outline of the main steps in Toyota’s productdevelopment process appears in Table 1. After this, the dies go throughseveral iterations of “tuning,” a process in which the dies are adjusted until
the parts meet the design dimensions and tolerances. Only in rare cases areimperfect parts accepted into the final car, a process called “functional build”
in the US car industry. The reason why the design dimensions are sought isthat these are the dimensions prescribed by the design standards, from which
the behavior of the car is supposed to be predictable. Using these
dimensions reinforces the standard; deviating from them creates confusion,
reduces confidence in the standards, and causes problems with
documentation of the as-built condition. If deviations are necessary because
the predictions were not borne out, the standards are updated.

Table 1: Outline of Flow of Product Development at Toyota
Advanced Engineering
Development of New Components, Machinery, Structures, andPlatforms
Product Development
Concept Development (including styling)
Product Planning
Product Design
Product Engineering (Prototypes, Performance, Functional Evaluation)
Production Preparation
Production Planning
Production Process Planning
Production Equipment Planning and Procurement
Build Mass Production Prototype
Preparation of Production Processes (Work Stations)
Production
Start of Mass Production
Hino says, and Morgan seems to say, that in recent years prototype buildsof parts, subassemblies, and cars are made using the dies that will ultimately
be used for final production. The study on which this research note is based
corroborated the view espoused by Hino and Morgan.
Estimates of how long the various stages last differ, but there is agreementfrom Hino, Morgan and Fujimoto that the time from approval of the Chief
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Engineer’s concept to styling freeze is a little over a year, the time from stylingfreeze to release of CAD data to the die shops is 6 months or less, and the timefrom first dies to start of production is a little over a year but as short as 8months in some cases.
During the design stage, the design engineers can usually tell if theirdesign cannot meet the targets, because the standards will reveal this.
Usually they do not propose designs that are unable to meet the targets. If
design or styling wants to push into a new area, the Evaluation Department iscalled on to do special calculations or experiments. The Advanced
Engineering Department will do this for more extensive exploratory designs
or new technologies. Untried designs and technologies apparently are notused in new car programs.
Evaluation iterations are carried out by styling, design engineering, andproduction engineering working together. The factory manufacturing
engineers are involved from time to time but mainly their interests are
represented by PE. As the process goes on, suppliers are involved more andmore. Since the standard design is expected to work to deliver performancetargets, the main activity during this period amounts to ensuring that thisdesign can be delivered with the required productivity and cost. The
tradeoffs therefore involve manufacturability, not whether the design targets
can be achieved. Several people said that the priority is performance quality
first, then appearance quality, then manufacturability (that is, manufacturing
cost and efficiency). In other words, the company believes that “the user
comes first, the dealer second, and the manufacturer third.” Since
performance quality is most noticeable to the customer, and since PE isbasically the guarantor of the ability of the actual physical product to deliver
performance quality, PE has considerable influence during styling and3
engineering design. Also, since appearance quality, for which PE also has
responsibility, has a slightly lower priority than performance quality, somepressure on the plant to emphasize appearance (such as gaps and flushness
between adjacent exterior parts) is reduced.
As always, when there aretradeoffs, it helps to have consistent priorities.
As in all companies, power shifts around over time. This study foundthat some important outsourcing decisions are made with such influence inmind. Thus one reason why critical items like instrument panels and doors
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Morgan compares Toyota with a “North American competitor” (NAC) andsays that the NAC does not have people who do what such vehicle
production engineers do at Toyota. Few companies in any industry except
semiconductors, to the authors’ knowledge, have the organizational structureor the capabilities that PE has at Toyota, and only in rare cases domanufacturing people have a strong influence on design. In semiconductors,
product and process are essentially the same thing.
7are kept in-house is so that Toyota can build up the technical andmanufacturing management skills of its personnel. If an engineers’ role
was mainly to oversee and give guidance to suppliers, they would have toomuch power since the suppliers would do what the engineers told them.
Keeping such designs in-house exposes the engineers to the full force of the
tradeoff discussions with production and PE and helps maintain a balance inthese critical and extended discussions.
PE or the manufacturing engineers are constantly seeking to detect a
feasibility or cost problem. When they do so the PE personnel not only flag
the problem but also strive to suggest feasible and reasonable changes. Thismeans in practice that PE must understand how the design works. This dual
capability of PE is discussed more in a later section.
As an enabler of this schedule, all main stamping dies are made at theMotomachi plant or Teihou plant (both located inside Toyota City), or by local
suppliers. This makes it possible to tune the dies quickly. When
production will be done at overseas plants where long shipping times are
required, it is necessary to reduce the amount of tuning done at the overseas
plant. When Whitney visited Toyota in 1991 he was told that die accuracy
was within 20μ of the CAD data. Today it would seem to be closer because
Mr I. said that essentially no hand finishing of the dies is needed, whereas in1991 some was. All of this is consistent with observations from this 1991
visit as well as Whitney’s general observations about outsourcing strategy at
Toyota and other Japanese companies: the main strategically important
technical knowledge and skills related to both product development andmanufacturing (what Whitney b c calls the “infrastructure of productdevelopment”) are kept in-house and nurtured.

2. People
Sobek reported on the importance of career paths at Toyota for ensuringthat top managers had strong technical skills, including what he called“connection knowledge,” meaning the ability to understand the car as acomplex system of interacting subsystems. It is also well known that people
stay in their jobs a relatively long time at Toyota (generally 4 to 6 years ormore), compared to other car companies, especially US companies. On thisvisit, these points were confirmed and amplified. We learned that Mr. O.’s
career path, mainly in PE (but also including some experience in the design
function), began with 6 years in PE, followed by a period doing productengineering for plastic and press parts, 10 years doing development of inhouse interior plastic parts production methods and production preparation,then various positions in PE planning performing vehicle cost planning andproduction planning. Mr. Su. started his career in the manufacturing
division at Toyota in an engine plant, spending 7 of 10 years in casting8

technologies plus other assignments in block machining and quality
improvement, then 3 years at a vehicle assembly plant focusing on assemblyline plant engineering and equipment maintenance, then onto assignments in
PE, consisting of 5 years planning assembly lines and 7 years (ongoing today)in door PE.
Mr. Su. calls himself a “player-manager” and says that all managers up to
his rank (group manager) must play this dual role in order to be able to teachtheir subordinates how to do their jobs. This policy also ensures the4technical competence of the managers. Mr. O. said that perhaps 10 years
ago a more typical “manager” philosophy was put in place but the result wasthat senior managers lost too much technical competence, so the playermanager system has been reinstated. Nevertheless, managers above Mr.
Su.’s rank must choose whether to continue as player-managers or shift to a
management position which has more of a “managerial” orientation. Chief
Engineers in product development are chosen from people who take theplayer-manager path.
Mr. Su. oversees a group of 8 Toyota people including himself, plus 8
supplier representatives, 3 temporary contract engineers, and a number oftechnicians. He is one of 5 managers at this level in Vehicle PE, the others
dealing with other segments of the car body. The division he is in,Interior/Exterior PE Planning, has about 40 Toyota engineers plus 20-30
supplier people. Within this organization there are 5 groups, which deal
with planning, exteriors, doors, instrument panels, and interiors.
Vehicle PE is one of the core divisions for production engineering ofvehicles and altogether it has about 600 people (180 Toyota engineers, 170
Toyota technicians, and 260 supplier representatives). Vehicle PE planning
seems to have an additional role, described below, of integrating a number ofthe body manufacturing specialties and at the same time integrating themwith engineering design and styling of bodies and interiors. In Toyota City,
the company has an astonishing 8000 people in all of PE. There may be as
many as 1000 in the US, and several hundred in Europe, where Toyota plans
to have more. Table 2 lists the departments in PE.

4Spear also describes this responsibility of managers to teach their people andcalls it part of Toyota’s “DNA.” Hino also uses the metaphor of DNA to
describe Toyota and provides historical evidence for how it was built up.
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Table 2: Production Engineering at Toyota(2 Shitsu [offices] and 23 Bu [divisions])
Koutei kakushin suishin shitsu [Office for promoting plant innovation]
Anzen kenkou suishin bu [Division for promoting health and safety]
Puranto enjiniaringu bu [Plant engineering division]
Seigi kanri bu [PE control division]
Seigi kaihatsu bu [PE development division]
Paatonaa robotto kaihatsu bu [Partner robot development division]
Seisan butsuryuu shisutemu seigi bu [Production logistics system PE
division]
Keisoku gijyutsu bu [Measurement technology division](Vehicle area)
Sharyou seigi bu [Vehicle PE division]Puresu seigi bu [Stamping PE division]
Bodei seigi bu [Welding and Painting PE division]
Kumitate seigi bu [Assembly and Plastics PE division](Unit area)
Youso seigi bu [Component PE division]
Yunitto shisakui bu [Unit prototype division]
Enjin seigi bu [Engine PE division]
Doraibutorein seigi bu [Drivetrain PE division]
Shashii seigi bu [Chassis PE division](HV / electronics area)
HV seigi bu [Hybrid vehicle PE division]
Hirose kikaku Kanri shitsu [Planning office]Denshi seigi bu [Electronics PE division]
Denshi yunitto seizou bu [Electronics unit production division](Production equipment area)
Kouki kanri bu [Production equipment control division]
Mekatoro‐ shisutemu bu [Mecha‐tronics and System division]
Sutanpingu tuuru bu [Stamping tools division]
Dai enjiniaringu bu [Die engineering division]

C. The Role of PE
The mission of Vehicle PE is to deliver a vehicle that is easy to build andachieves the quality goals, such as door closing effort, water leakage, and theother customer attributes. This is a difficult job because it spans two
typically separate domains in manufacturing companies, namely engineering
for customer attributes and manufacturing for low cost and high efficiency.
Furthermore, PE does not actually directly do either of the functions. That is,
it does not design the car and it does not build the cars or components in thefactories on a daily basis. The overall product development process, as
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described above, is assumed capable of creating designs that meet the
attribute targets but it is also necessary to achieve manufacturability, cost, andefficiency targets with respect to the actual physical objects that are produced.
Stamping and welding people, for example, look for problems in theirareas, such as parts that can’t be stamped or weld locations that can’t bereached by the welding equipment. Discussions with the design department
prior to freezing the CAD data start early and are ongoing, frequent, andintense. As mentioned above, no one can identify a problem without
offering suggestions for how to fix it. This was described to us as part of“our company’s culture,” which was also described as “working together forthe customer.” In other companies, we were told, “targets seem to be driven
down to manufacturing, which has to deliver them” and “Other companies
seem to go to production without having met the attribute targets.” Toyota
people say that they do not do either of these things.
Each class of car has its own targets. These are set well above what
Toyota thinks the market will regard as the minimum for that class, so there isa range in which tradeoffs can be negotiated. But generally the targets are
regarded as requirements. These are hardest to achieve both in luxury cars
because their buyers demand so much, and in low-cost cars because there aretight constraints on costs that may be devoted to solutions. Great cleverness
and resourcefulness are required. Yet Toyota people are confident that they
can reach the targets because they have done it for many years. A cost or
weight increase may be the only solution but it is a last resort.
Since attributes conflict and since targets usually rise, this is a difficult
process that gets more challenging every year. The “pain” is usually sharedacross the different manufacturing domains, and PE has taken on the role ofnegotiating among these domains before going back to engineering design
with suggestions. PE’s role with respect to the manufacturing domains
seems appropriate since PE considers manufacturing variation and its effecton the targets. Variation can arise in any domain, so it is necessary forsomeone to look for the best way to solve problems independently of theinterests of any one domain. This role equips PE to act as the interface backto engineering. How and when PE took on or was given this role is not5
known to us and was not a subject of discussion during this visit.
In summary, door design is managed in two main ways: (1) standards,
checklists, and limited menus of design alternatives are used to guide thedesign toward the right solutions from the start; and (2) strong
representatives from PE are part of the design process, reviewing, finding
problems, suggesting solutions, and generally being partners in coming up
5

In general, the history of these arrangements is important to know. Both
Hino and Fujimoto have written whole books about just this aspect of Toyota.
11with the final design. This shared set of responsibilities extends through thedie tuning process and into the launch of the new car. Toyota keeps inhouse the main skills and technologies needed to sustain this process andemploys personnel policies that encourage technical depth in its engineers
and managers.

IV.

Observations
A. History of Standardization at Toyota

Hino shows that several features of the above process have been part of
Toyota since it was founded in the early 1930s by Kiichiro Toyoda. Kiichiro
did several things analogous to what Sloan did at General Motors 10 years
before, namely establish the structure and operating principles of his
company. Many Toyota practices, including JIT and standardization,
originated in the need to achieve higher quality, save money and save time,
but have gained in strategic value over the decades. The company grew its
skills in design, quality (at first embodied as durability, later as performanceand appearance), and manufacturing. It documented its knowledge andexpressed it as standards for all essential procedures in the company. This
study and the academic research cited in this research note mainly reflect theevidence of standards and documentation in product development
engineering and production engineering. Beyond this is the fact that thestandards today embody a standard of behavior, namely that good behavior
means adhering to the standards, reading the documents, being pro-active
about suggesting improvements, and updating the standards when
improvements have been found and verified.
There appears to have been some deterioration of the standards process inthe heady days of the 1980s. This is the time when the “heavyweightprogram manager” approach was in full swing. Clark and Fujimoto andothers have found that these program managers wanted their cars to be
distinctive and optimally designed. The result was proliferation of parts and6components, such as dozens of steering wheels and engines. The market forcars in Japan began to decline in 1991. Serious problems emerged at Toyota
and other companies around this time as exports also stopped growing
rapidly followed by drastic yen appreciation. Toyota took steps to further
reduce costs and re-establish standards discipline particularly in the area of
6

Cusumano and Nobeoka discuss efforts at Japanese automakers to tackle theissue of parts proliferation through more systematic sharing of components
and technologies across models in the 1990s. See also related discussion on“fat product design” or the trend toward over-designing of parts andcomponents at Toyota in the 1980s [Fujimoto].
12simplifying product designs and reducing proliferation of different types ofparts. By 1995 plans were in place or under way. Thus many of our hosts
refer to the current state of standard designs for doors as dating from 1995 as
though Toyota started over around that time. But apparently 1995 marked areturn to a much older tradition.
Morgan’s thesis is dated 2002 and represents observations made in 20002001 of a smoothly-running standardized process. By the time of this visit,
2007, the 1995 process has had 5 years to prove the validity of the standards
and 6 more to refine and exploit them.

B. Production Engineering as the Integrator
This study was predicated on several assumptions, some of which proved
accurate while others did not. The main assumption was that Toyota is goodat system engineering. This impression was gained from prior research andvisits to Toyota as well as research by Morgan, Sobek, and Fujimoto. This
assumption remains intact. A derivative assumption was that doors requirea systems approach because they embody so many challenging andconflicting requirements. This assumption remains intact but should be readin conjunction with the next derivative assumption, namely that Toyota has
adopted explicit and conscious methods for balancing and trading off theattributes. This seems not to be the case. Instead, the basic tradeoffs
decisions were made 10 or more years ago and embodied in design standards
and manufacturing reconciliation methods that seem always to be able tomeet the requirements, given sufficient discussion, cooperation, andingenuity. Thus the term “systems thinking” does not seem to be common.
Rather, the system engineering process has been internalized as the right way
to behave, consistent with the culture of putting the customer first, working
together, and adhering to the standards. Other specific and well-known
methodologies, such as Design for Assembly [Whitney b], the Taguchi
method, and the House of Quality (QFD), are not practiced explicitly.
Instead, by means of experimentation, documentation, and continuous
improvement, a set of workable design methods and standard design choices
has emerged which together produce good cars.
Production Engineering, particularly I/E Planning and Vehicle PE, has
emerged to play the role of system integrator, at least in the body engineering
part of Toyota’s product development process. Whitney’s research on
assembly over several decades has shown that design of assemblies andassembly process design can act as an integrator of product development[Nevins and Whitney] [Whitney d]. It is fascinating to see this in action at
Toyota. I/E is in a position to face both ways. With regard to the separate
manufacturing engineering skill domains like stamping and painting, it can
act as a mediator, seeking the most effective set of suggestions to take back to13

engineering. Within the engineering design process it can anticipate theproblems of the manufacturing domains, give the engineers early warning,and seek mutually satisfactory solutions.
In terms of management principles, what was described by interviewees(and is not widely discussed in the academic literature) is the extent to which
typical principles of specific roles and responsibilities are not adhered to at
Toyota. What was seen on this study is interpreted as comprising typically
clear roles (A is a design engineer, B is a PE engineer) but untypically blurredor shared responsibility, especially responsibility for delivering the targets.
There is a saying “When everyone is responsible, no one is responsible.” But
this saying is made with respect to the ability to find out whom to blame. It
is not a management principle. Instead, we might imagine Toyota saying“When everyone is responsible, everyone is responsible.” This accords
somewhat with the idea of the “high reliability organization” (HRO)
identified by social scientists and researchers studying system accidents[Weick et al.]. Here the idea is that complexity cannot be managed withovert procedures alone and instead everyone must be mindful of problems
that could occur and help protect others from them. Toyota has adopted
standards and documentation as the first line of defense in this complex
environment but has developed shared responsibility as the second line.
HROs are no different in either respect. Toyota does not use any of thecustomary terminology of the HRO community, but such terminology seems
applicable to product development, as has been pointed out in an
unpublished study [Whitney d].

V. Closing Remarks
This research note argues that Toyota continues to pursue basic strategic
decisions and policies regarding the infrastructure of product developmentthat have been in place for many years, some for decades. These compriseattitudes toward technology and people that encourage depth of in-house
knowledge, recognition of the importance of understanding interactions
among the elements of its complex product, and adherence to provenmethods as a response to that complexity. These policies have led Toyota to
be a strong company able to deliver reliable cars quickly, but also may havecreated a conservative culture. This is not the only business model for
success in the car industry but it may be the best for a company addressing
the mass market. A major challenge for Toyota is to grow rapidly worldwide while relying on a learning process whose time-constants are measured
in decades.

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VI.

References[Clark and Fujimoto] Clark, K.B. and Fujimoto, T. Product Development
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[Cusumano and Nobeoka] Cusumano, M. A. and Nobeoka, K., Thinking
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[Fine and Whitney] Fine, C. H. and Whitney, D. E., “Is the Make-Buy Decisiona Core Competence?”
http://esd.mit.edu/esd_books/whitney/pdfs/make_buy.pdf[Fujimoto] Fujimoto, T., The Evolution of a Manufacturing System at Toyota, New
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[Liker] Liker, J. K., The Toyota Way, New York: McGraw-Hill, 2003
[Hino] Hino, S., Inside the Mind of Toyota, New York: Productivity Press, 2002
(English Translation 2006)[Morgan] Morgan, J. M., “High Performance Product Development: A
Systems Approach To A Lean Product Development Process,” PhD Thesis,
University of Michigan, 2002
[Nevins and Whitney] Nevins, J. L. and Whitney, D. E., eds, Concurrent Designof Products and Processes, New York: McGraw-Hill, 1989
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Systems: A Toyota-Chrysler Comparison,” PhD Thesis, University ofMichigan, 1997
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[Whitney a] Whitney, D. E., Mechanical Assemblies: Their Design, Manufacture,
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[Whitney b] Whitney, D. E., Toyota Visit 1991
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[Whitney c] Whitney, D. E., Japan Final Report 1991
http://esd.mit.edu/esd_books/whitney/pdfs/final-j.pdf[Whitney d] Whitney, D. E., “Combating System Problems in Complex
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