The traditional approach has been that a product was created by the design engineers and handed to manufacturing or the supplier to produce. The result very often was costly and the product not easy to manufacture. For instance there could be too many different types of fasteners, or the product may continually fail final test. A series of modifications was then needed to "sort out" the worst problems

The "Design for Manufacturability" approach requires all parties to be involved in the total project from start to finish. The aims include the simplification of parts, products, and processes to improve quality and reduce manufacturing costs. With improved quality and a simplified design, the reliability of the product should be improved.

The design of a product can be viewed as a separate process, or as part of a long integrated chain of events aimed at satisfying customer needs. The design is always primarily focused on the paying customer but the many customers internal to the organization must also be considered, because it is through this team that the final product is completed. The integrated approach will lead to the inclusion of considerations of manufacturability during the design stage.

Obviously the function of design cannot be successfully completed by people who are not intimately aware of all the relevant aspects influencing the manufacture of the designed item. A team approach is required from the start. This is also known as Early Manufacturing Involvement (EMI). A typical design team should consist of design engineers, marketing, production, value and quality engineers, as well as production planners. For items to be designed and then produced by outside suppliers, it is essential the suppliers are involved at the design stage and made part of the total design team. It is best if the total design team is located close to the manufacturing site so that feedback is received and changes or improvements can be implemented immediately.

Cross-training, by placing designers close to the customer and in the manufacturing arena, serves to increase their ability to understand the problems on both sides. There is a lot of potential for waste in designs created in a vacuum, leading to many modifications which increase costs and lead time. In the case of making an automobile, fully 70% of the total cost can be pre-determined by the design function, while in other industries the figure can be 80%. A very basic example is fasteners - screws, bolts and so on. If designers do not think about the number of fasteners they design in, or the number of different types, or the time taken to fit them, both purchasing and shop floor people can find they have to devote an awful lot of time to a very humble item.

On the other hand, we should not imagine that design rules are quite that simple. We need to think about the matching of components, mold design and so on. Engineering changes should be reduced to a minimum by working through as many issues as possible before start up. Value engineering, which is a disciplined approach to the elimination of waste from products or processes via an investigative process, focuses on the functions to be performed and whether such functions add value.

Firstly we must know what the customer wants, then be capable of jointly designing a product to meet that need, which is practical for manufacturing to produce economically. The final product must not only meet the need of the customer initially, but continue to meet the need during its life; it must be reliable.
 
 

November 1999