Deep Tray Dilemma

On today’s issue of Cliff’s Chronicles:

“I was walking the floor with a customer not long ago, and they were struggling to mold a 12” x 14” x 1” deep tray. The process technician was pulling out his hair because the part kept warping. The base would twist, and the corners would lift.

The key requirement was flatness. The tray was used indoors to move work in process (WIP) molded plastic components from work cell to work cell. There were no extraordinary requirements: no elevated temps, no chemicals, and no U.V.

The OEM who specified the design also specified the material, which was homopolymer acetal that shrinks 0.020 in/in. Why was homopolymer acetal specified? It was being used in various other components like washers and gears. The process technician was fighting an uphill battle because the material had been selected, not for its performance in this tray application, but because it worked in various other components that were critical. The assumption was that it would also work in this noncritical application.

With minimal tooling changes, the mold was re-worked to run unfilled INTEGRA® ABS 10GP. The performance needed to move the WIP components was achieved: flatness. We are continuing to follow up on the next challenge: how quickly the process technician can regrow his hair!”

Need help from Cliff and the Fixers at PolySource? Contact us today to learn more about our expert consultation services.