Oftentimes past experience guides decisions, but when competing materials or processes are considered the familiar one tends to win solely on the basis of precedence. This may be a fail-proof choice in most cases, but leaves out the consideration of the market's ability to offer cost savings. Alternate materials and processes that may perhaps be better suited for the current product and offer not only efficiencies in manufacturing, but time savings to market and overall production cost reductions.
By engaging with the sourcing group the design team can integrate real market data to rationalize the design under development with the current state of the supply base. Suppliers are experts in their fields and can act as advisers to constrain and guide broad design goals into clear specifications. Design teams certainly interface with their established suppliers on a regular basis, but the opinions may be very localized to the individual supplier's core capabilities and not be a true and objective portrayal of the market and their competition.
The areas we've seen most often have the greatest impact on final costs and time to market are materials selection and manufacturing process determination.
Material choice may not be an option in certain medical devices with bio-compatibility mandates or strict approval guidelines, but in most cases are seen from a simple mechanical property perspective such as hardness, elasticity, and yield strength or environmental factors such as corrosion resistance. In these cases a wide range of materials will fall within the range of consideration. If we take tooling for example, 316 SS, 304 SS, 17-7 SS, and 440C SS may all be applicable, while with engineered structural or automotive components Aluminum grades 6063 and 6061 are often comparable.
The choice then becomes one of precedence to use the common 316 SS since it's worked for other parts, or to explore alternatives. By contacting a range of small and large shops the sourcing team can quickly determine which materials are most commonly used by the shops, have the best raw material pricing and supply in your area, and which shops offer the best pricing. Often shops use a large quantity of a specific material with other clients and can offer cost savings even on low volume and high-mix parts lists due to existing relationships. A moderate heterogeneous sample set of suppliers will give the most objective quotes.
Manufacturing processes are often tightly coupled to material selection and shops design their floors around specific and expensive machinery they like to operate at high capacity. Newer processes such as MIM or alternates to tradition CNC/turning operations such as swaging may not be an option for incumbent shops, but other shops may specialize in these processes and offer considerable savings to produce the same quality part. Even a simpler consideration such as the broadening of non-critical feature tolerances can decrease the cost of the finished part by 20%-30%. The key is knowing both how the component is used and how it will be manufactured to minimize the costs.
Sometimes a combination of the right material and process is critical for cost savings, as is often the case in injection and compression molding. A non-significant change in material may allow it to be used on a much higher throughput machine and offer significant higher volume production savings that were hidden by initial costs incurred with low-volume runs.
When considered as a tool within the NPI process, sourcing can offer the critical insight on current supplier practices that will achieve time and cost savings not only for materials but also manufacturing process selection to insure the success of the finished product from NPI to full scale manufacturing.