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SPRINGING INTO ACTION TO SAVE FACE SHIELD

Background The in-house design team at 3M had reached quite an advanced stage in the development of a new type of face shield, but a few problems needed resolving before the design could be committed for tooling.

A set of CAD models had been created and some accurate SLA prototype parts had been made from them. End-user focus group reaction had been favourable. However, component supplier comments and tests on the prototype parts showed that although the basic concept was right, some of the details were not. SA was invited to contribute to finding solutions.

Challenge One major issue was around the way the transparent lens was fitted to the frame. Some of the moulded details of the frame were extremely difficult to tool-up and the lens was not easy to fit.

A detent-click action was provided by a spring. The spring action felt just right, but the spring itself was over-stressing the moulding that it was attached to. This was distorting the prototype parts and would have led to unreliability in the longer term.

SolutionSA sketched out concepts for the frame and the lens to eliminate the features that were difficult to tool, while at the same time making the lens much easier for the end user to fit. This was done through close liaison with the key suppliers and without significantly altering the appearance of the product.

SA then came up with several alternative spring concepts, each capable of delivering the same acceptable user-feel, but without over-stressing the spring anchor points. One of SA’s solution’s was chosen and SA prepared detailed engineering drawings and got the parts made.

Deliverables SA gave clear and expert advice to the design team, enabling them to alter the 3D CAD model of the frame and get new parts made. SA then went with 3M to the various suppliers to verify that the improved designs would be easy to tool up and would mould successfully. Test results on the improved spring showed that it met the performance criteria and did not over-stress the plastic parts.

Results SA helped turn a good concept into a production-ready design. The 3M Face Shield does the job it was created for.