Concurrent Engineering is also sometimes referred to as simultaneous engineering. Under this foundation, all of the life cycle processes of a product would be conducted parallel in time to one another. However, it is not possible to all the aspects of production to occur completely simultaneously. A more accurate term then would be overlap engineering that contradicts traditional methods. In the book Concurrent Engineering Effectiveness, Mitchell Fleischer explains, "For example, work on developing downstream systems begins before work on developing the product itself is complete. This is in direct contrast to more traditional approaches to product development in which the process proceeds sequentially"(8). .
.
The traditional sequential process, sometimes called the waterfall approach, has been the standard for many years. This methodology has worked successfully under the assumption that changes will be made and it would be wasteful to begin on step 2 until step 1 has been fully completed. However, sequential design does carry with is inherent flaws. It is obvious from the chart that sequential design requires a much greater deal of time, and lead times can become enormous. The feedback loops in Concurrent Engineering are also much shorter. In traditional methods the product is made long after it is initially designed. Any errors that require engineering changes will create a large loop further lengthening design-to-market times. At this point, going back and changing the entire product development process to correct the error would be very expensive. Finally, "You can't finalize the design of the product until you know how it will be made"(Fliescher). An engineer can design a beautiful part on a computer CAD program, but if he does not understand the manufacturing process, problems can arise. Some parts can simply not be made as initially drawn, or else the costs to produce a part as drawn are much too high.