The prototype development cost was approved and the customer issued a purchase order. Flextech built the prototype tool and sourced cross-linked polyethylene foams of various densities that we would use to mold prototype parts. Our intention was to provide our customer with a range of materials to evaluate and test.
We initially struggled with compression molding the trays due to their significant draw ratio – the height or depth of a part relative to its perimeter dimensions. In the deepest tray features, the foam was stressed and tore during the molding process. Typically, using a mold release agent would solve the problem. However in this case, because the tray is used to package a sterile medical device, a release agent would compromise the pump’s sterility.
In order to mold the foam tray parts without tearing the material, our R & D team experimented with a number of process variables that can affect the material and the parts. After considerable experimentation we made adjustments that allowed us to successfully mold the prototype parts with no defects.