Polyolefin reduces warping in cowl grilles
By Julia Kuzeljevich
When excessive warping became a problem for the cowl grille of the Chevrolet Lumina and Monte Carlo, GM , injection molder Venture Industries and Solvay Engineered Polymers decided to convert from an ...
When excessive warping became a problem for the cowl grille of the Chevrolet Lumina and Monte Carlo, GM , injection molder Venture Industries and Solvay Engineered Polymers decided to convert from an ASA/PC blend to a material with greater dimensional stability.
The material selected, Solvay SEQUEL 1733 engineered polyolefin, exhibits low coefficients of linear thermal expansion (CLTE). The material has a flexural modulus of 295 kpsi, extremely stiff for an engineered polyolefin. Its heat-deflection temperature (241F at 66 psi) is comparable to that of the ASA/PC blend it replaced, but it has a lower specific gravity of 1.05.
The mold shrink of this engineered polyolefin was adjusted to 0.7 percent so it could be dropped into the production molds without any changes to the tooling.
Cowl screens molded in SEQUEL 1733 polyolefin were attached to a full front-end buck and evaluated side by side with the original parts in a rigorous hot-cold cycle procedure. Test temperatures were cycled repeatedly between 240F and -20F for extended periods. The dimensional stability of parts molded in SEQUEL 1733 material was confirmed by this testing, and the new polyolefin went into production as a running change.
Solvay Engineered Polymers 248/391-9500
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