Molded helm steers a winning course

The helm of a pontoon boat took Product of the Year honors in an annual design competition sponsored by the Association of Rotational Molders International, Oak Brook, Ill. (www.rotomolding.org). The linear low-density polyethylene (LLDPE) helm came from Elkhart Plastics Inc., Middlebury, Ind. (www.elkhartplastics.com). It was also tops in the Conversion category -- previously the helm was gel-coated fiberglass. The competition also handed out awards based on PVC use, for large parts, and for recycled material use.

Elkhart modeled the helm and all its major components in SolidWorks. Elkhart spokesperson Glenn Howard says solid modeling was key for confirming component fit and function as well as letting the OEM evaluate part aesthetics before tooling up. The solid model data was used to build the aluminum molds that were either cast or CNC milled.

Elkhart also built a full-scale wood prototype of the upper portion of the helm to help form the gage panels and windshield. The firm also devised a test mold with a highly polished surface to run prototypes. The test parts verified the helm was opaque and had a glossy surface similar to that of its gel-coated predecessor.

Molds were also equipped with an internal air pressurization system that helped reduce part distortion and warping. Secondary operations included trimming, cutting the gage panel openings, and attaching the storage compartment door and access panel door to the unit.