15. PACEMAKER HEADER MOLDING

A. Problem/Issue

A cleanroom injection molding company was doing the molding for two pacemaker companies. They were having trouble with contaminants inside the urethane molding. If the contaminant broke through the surface, the part was rejected. They were looking for improvements to their process. They also had problems meeting customer tolerance specifications from existing proprietary tooling they were using.

B. Analysis

We analyzed the pellet feeding mechanism and tested the raw resin for contaminants. We also looked at tolerance stack-up from customer prints in compared to processes in place at the time. We compared them with material shrinkage over time and got a better understanding of the material characteristics before, during, and after molding.

C. Solution/Results

We discovered that there was a 75% chance that there would be a contaminant inside each molded header using existing material, packaging, and processing. We also determined that the customer print had to have a slight tolerance change in order for the part to me molded and secondary fabricated to print. This led to a new format for dimensioning tooling necessary to mold the header. The packaging and delivery system were changed in order to reduce the contaminants. A novel cleaning method was suggested to rid the raw pellets of processed-in discolored pellets.