Boyd Allin

Don’t Forget the Tooling Engineer in Medical Device Design

The design team for a medical device or consumer product is usually multidisciplinary and can incorporate: physicists, biochemists, optical engineers, mechanical engineers, electrical engineers, software/firmware engineers, industrial designers, user interface specialists, ergonomic experts and specialists unique to the demands of the project. These wonderfully powerful and talented teams can be undermined by omitting a critical expertise – tool design engineers.

Many product prototypes incorporate rapid prototype surrogates for injection molded parts. It is following this prototype phase that companies can overlook the need to further augment the design team with a tooling engineer. Often the design team “throws the design over the wall” to a tool maker/injection molding house and expects the parts coming back to reflect with high fidelity the CAD models. I have seen the derailing and failure of great designs because of inferior tooling and part processing. The lack of input and buy-off on the tool design and part processing from a tooling engineer on the design team can be catastrophic. Adding a tooling engineer to the team before sending the parts to the tool maker is a potent way of reducing the risk that the parts produced are structurally sound, accurate, repeatable, cosmetically optimal and can be modified with minimal effort.

An injection molding house may have many tooling engineers; however, they have an inherent conflict of interest with you as the designer and in the case of a consultancy, with your client. This conflict of interest arises because of the tool maker’s incentive to make the tooling in the most inexpensive and most rapid way possible. This priority can lead to the selection of smaller than optimal mold bases, insufficient and undersized cooling lines, lack of interlocks, undersized gates, foregoing mold flow analyses, undersized ejector pin retraction springs, selecting cheaper steels than required, foregoing inserts where required, inadequate venting, limited or no wear plates and a host of other short cuts. These short cuts are difficult to remedy after the tool is completed and the ramifications and cost benefit trade-offs are difficult for anyone but a competent tooling engineer to opine on. Experienced designers understand a great deal about injection molding; however, they simply do not have the same level of niche expertise as a dedicated tooling engineer.

Clients procuring design work or companies designing a product have a tendency to look at how well the prototype works and how polished the CAD appears and dismiss the problems that can occur in translating these embodiments into a production product. The case for including a tooling engineer in the translation of the CAD models into steel and finally molded parts is not an easy sell to make to a prospective client; however, the costs in terms of schedule and dollars by not doing so can be staggering. Building in the costs and minimal adder to the schedule to leverage this speciality should not be overlooked or under-valued.

Commercialization Consult



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