The second paradox can be summarized in this way: Toyota considers a broader range of possible designs and delays certain decisions longer than other automotive companies do, yet has what may be the fastest and most efficient vehicle development cycles in the industry. Traditional design practice, whether concurrent or not, tends to quickly converge on a solution, a point in the solution space, and then modify that solution until it meets the design objectives. This seems an effective approach unless one picks the wrong starting point; subsequent iterations to refine that solution can be very time consuming and lead to a suboptimal design.
A wide net from the start, and gradual elimination of weaker solutions, makes finding the best or better solutions more likely. As a result, Toyota may take more time early on to define the solutions, but can then move more quickly toward convergence and, ultimately, production than its point-based counterparts. We present the conceptual framework of SBCE in more detail, tying it in with other characteristics of the Toyota development system, and discuss why the SBCE principles lead to highly effective product development systems. Many of the challenges focused on the more extreme examples we offered.
We said, for example, that Toyota broadly explored body styles and could consider anywhere from five to twenty different styling alternatives. And we suggested that final styling decisions could wait as long as the second full-vehicle prototype, at the extreme.
- Heavens Gate.
- Multi-volumed work.
- 1. Introduction.
- Srebrenica.I giorni della vergogna (Orienti) (Italian Edition).
These extreme cases were intended to be just that —extremes to demonstrate a point, not averages. More important than the specific numbers were the underlying principles of design that Toyota followed. We chose these examples to illustrate ideas, not to suggest that if a company makes lots of prototypes or waits until the very last minute to make decisions, its development process will improve. In fact, a good job exploring solutions on one project can lead to a very focused search and much more rapid convergence on a design in later projects.
Both the novelty of the idea and the skepticism we encountered led us to develop the paradigm of SBCE further. We began by collecting more data. He interviewed managers and engineers from a broad range of design specialties including styling, body engineering, chassis engineering, power train engineering, vehicle evaluation, production engineering, and prototyping, and a number of closely affiliated Toyota suppliers.
In addition, we interviewed Japanese and U. Bringing its development system to the United States has forced Toyota to make its design philosophy and principles explicit. The training materials and process for U. Get semi-monthly updates on how global companies are managing in a changing world. How is Toyota able to do concurrent engineering so well?
Traditional, serial engineering is a series of functions, each designing to a single solution or point see top of Figure 1. Of course, this is a simplification; there are feedback loops, but the feedback from downstream functions comes later, often after upstream functions have committed to a particular solution. And, typically, the feedback consists of specific critiques that lead to minor changes to the base design.
Serial engineering is fraught with shortcomings due to the delayed feedback loops. As usually practiced, CE attempts to bring more feedback upstream earlier, generally through face-to-face meetings. Typical CE in the United States is a refinement of point-based design, but still does not break out of the paradigm. The typical CE process looks something like the lower part of Figure 1. A function such as styling comes up with a design solution and very early in the process shows it to other functions for input. These downstream functions analyze and critique the design from their perspective.
For example, the top members of a Chrysler design team meet for an entire day every week.
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Since this is done early, changes to the styling design are relatively easy and inexpensive, and ideally, the design team soon arrives at a solution that will satisfy all parties. While an improvement over serial engineering, the basic picture remains the same: the design team is iterating on one solution. Problems with such an approach arise when engineers try to work concurrently with other development team members. As the design passes from group to group for critique from different functional perspectives or even if they are critiquing it as a cross-functional team , every change causes further changes and analysis, resulting in rework and additional communication demands.
There is no theoretical guarantee that the process will ever converge, and hundreds of engineers have told us that it often does not: the team simply stops designing when it runs out of time. Since the development organization never gets a clear picture of the possibilities, the resulting design can be far from optimal. Despite these drawbacks, many companies have been successful with iterative, apparently point-based models. Combining this very fast iteration with modular product architectures and extremely skilled programmers enables Microsoft to remain a leader in the software industry.
Similarly, Terwiesch et al.
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Design participants reason about, develop, and communicate sets of solutions in parallel and relatively independently. As designs converge, participants commit to staying within the set s , barring extreme circumstances, so that others can rely on their communication. In Part A, the two functions, design engineering and manufacturing engineering, define broad sets of feasible solutions from their respective areas of expertise principle 1 — map the design space.
In Part B, design engineering then smoothly refines the set over time by eliminating ideas not feasible from the manufacturing perspective principle 2 — integrate by intersection. Design engineering continues to refine the set through further design and development work, while manufacturing engineering is also designing and refining at this stage.
In Part C, the two groups continue to communicate about the sets under consideration, ensuring producible product designs while enabling manufacturing to get a jump start on design and fabrication of the production process principle 3 — establish feasibility before commitment.
The gradual convergence to a final design, Part D, helps the development team make sound design decisions at each stage. Gradual convergence also allows both functions to work in tandem with little risk of rework. Figure 2 is highly simplified, with only two actors. SBCE works in the context of many actors defining sets, communicating sets, and converging to mutually acceptable solutions that optimize system performance, not individual subsystem performance.
SBCE assumes that reasoning and communicating about sets of ideas leads to more robust, optimized systems and greater overall efficiency than working with one idea at a time, even though the individual steps may look inefficient. In practice, the costs of eliminating all back-tracking could probably not be justified. But a focus on convergence, rather than on tweaking a good idea to optimize it, can dramatically reduce the amount of back-tracking in the process. The following examples demonstrate a range of approaches explored in detail later that are all consistent with the underlying philosophy:.
All three examples involve reasoning about sets of alternatives and a sophisticated understanding of the boundaries on the solution space. Later, we describe the underlying principles of SBCE in greater depth, along with additional detailed examples from Toyota automotive development. Students of design and creativity have traditionally emphasized looking at many ideas.
This method, Pugh claims, can apply to any phase of the design process, not just to concept selection. Iansiti describes a product development team at NEC that carried four distinct product concepts in parallel and worked for two years on design and development to arrive at a final concept.
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For example, many of the authors mentioned above seem to assume that a colocated team looks at the sets together, allowing informal communication. At Toyota, communication about sets is explicit. These authors also imply that the sets are discrete lists of alternatives, ignoring other ways of representing sets. Liker et al. Otto and Antonsson, Ward, Lozano-Perez, and Seering, and others have focused on formal representations of and inferences about sets of possibilities.
A large body of literature looks at the evolution of fundamental science and engineering innovations at the macro-level over time. Technology cycles are defined by dominant designs and subsequent technological discontinuities.
Product development of mature technologies involves integration of detailed design decisions about thousands of parts and interrelated subsystems. Toyota excels at this integration by keeping options open longer, communicating about sets, and breaking free of some of the cognitive constraints described by Nelson and Winter. Many factors contribute to the efficacy of the Toyota product development system; no one secret explains its success. SBCE is a critical aspect of the system, but it operates in concert with other, equally important principles on system design and the use of knowledge.
For example, Toyota develops deep technical expertise in both its engineering and management ranks. Managers are excellent, experienced engineers who continue to view technical engineering as at least the second most critical aspect of their jobs the most critical may be developing the engineers they supervise.
Outside their small staff, they have no direct authority over functional engineers who report to functional general managers. However, CEs are totally responsible for their vehicles, from the early concept stages through launch and into the initial marketing campaign. They perform vital systems integration, for while each function is responsible for its subsystem, the chief engineers are responsible for the total vehicles. The CEs make the set-based process work by controlling the narrowing process, insisting on broad exploration, resolving any disagreements across functions, and, when needed, making decisions on competing alternatives based on an analysis of trade-offs.
In our earlier article, we described many examples of SBCE but had not yet systematized these practices into an overall framework. Together, the principles create a framework in which design participants can work on pieces of the design in parallel yet knit them together into a system. The remainder of the article discusses these principles in detail. In product development, Toyota applies this principle on two levels. First, on individual projects, Toyota engineers and designers explore and communicate many alternatives.
Next we explore three elements of mapping the design space. Each functional department e. Engineering checklists or design standards are one embodiment of this principle. As an example, styling may have a checklist for the license plate well that contains dimensions, bolt-hole locations, regulations on tilt angles and illumination for various world markets, and restrictions on curvature radii and on the depth of draw, and so on.
This documentation may also contain descriptions of what can and cannot be economically produced along with solutions to past problems, information on how to accommodate new production methods like new automation, suggestions to improve quality, reduce cost, enhance manufacturability, and so forth. When the chief engineer asks production engineering to participate in vehicle development, for example, the first step is to pull the checklists from the files and customize them for the particular vehicle program.
Body engineering then updates its own checklists based on these documents in preparation for the body design phase and, in turn, gives its updated checklists to styling. Most U. Written manufacturability guidelines are sketchy at best, with most communication between manufacturing and design engineering being oral. At Toyota, engineering checklists are not simply long lists of design rules or guidelines imposed by a staff section. They explicitly define current capabilities as understood by the responsible designers.
For example, each part on the body has a separate manufacturing checklist maintained by the engineering group that designs the stamping dies for that part. It shows, for example, the range of flange angles that produces a good part, what kinds of interfaces avoid assembly problems, how to design slip joints for a robust fit, what areas of the part tend to have formability issues, and quick calculations on the risks of curvatures and deformations, and so on.
The engineers do not maintain detailed product histories but abstract their experience with each design to modify the checklist, further refining the possibilities.