Part proliferation happens out of ignorance, due to lack of guidance, proper design policies and supply chain knowledge. Most product designers (especially young ones), do not understand the importance of part standardization and the cost savings associated with it, as they are concentrating more in modeling parts on their CAD than understanding the whole system that surrounds product development. The author of this blog had a customer who had a major problem with part proliferation and it is due to the three causes listed previously. These causes have a ripple effect on the total operation and the total cost of the product. This happens because the Product designers don't spend the time looking for existing parts. As Dr. David M. Anderson says in Design for Manufacturability and Concurrent Engineering, "Never design a part that you can buy off the shelf". Product designers are the one controlling the BOM’s and if they don’t have this understanding, proliferation starts as soon as they start modeling the next project.
Why it happens?!
As we have already mentioned there are three basic causes of part proliferation, but we can easily list a slew of causes.
Simple part fallacy: Product designers see some parts as being simple to model, therefore simple to fabricate, therefore inexpensive.
Inexpensive part fallacy: product designers see hardware (screws, bolts, nuts, rivets …) as being inexpensive, yet the cost of maintaining an inventory of multiple fasteners to suit everyone's taste can drive production cost up exponentially and drive efficiency down exponentially.
Lack of global thinking: Sometimes Product designers fall in the trap of Not-Invented-Here, and will design a part that is probably available of the shelf.
Arbitrary decisions: Product Designers will often specify or design a part that does the job (but not more) for their specific application, when a standard part in store but a bit different may do the job, but is not chosen because of size, shape, or material.
Lack of Standard BOM: Many companies decide to create their Standard BOM as products are being developed without a clear policy, resulting in all of the above.
Strategy
If one starts a new line of product it is quite easy, however if one deals with an on-going product, strong leadership and time will be required.
The first target should be the elimination of duplicate, triplicates… and then evaluate if some parts can be grouped into one basic configuration that can be modified as needed.
The second target should be aggressive fasteners standardization.
The third target should be working with Supply Chain Management to create a preferred parts list that is as complete as can be, and if parts need to be added, authorization is required.
One way of performing a consolidation of parts, is the Empty Drawer Concept or also called the Empty Room Concept. The concept is very simple. Empty the drawer of all its content (in our case the store room) and only put what you really need. What you don’t need is either sold or disposed of; regardless of the disposal means, you do, don’t put it back in the store room.
Closing Comment
It is proven that part proliferation increases cost in product development and manufacturing as it impacts efficiency and profitability. If one needs to compete with manufacturers from less than low wage countries, we need to re-invent ourselves in the way we approach product development, and how it should be manufactured by eliminating the waste and cost that we assume being part of the game of developing products. Some part proliferation elimination projects have paid themselves within one quarter (3 months), and have generated further savings from an economy of scale.
