Effect of Molding Conditions on Part Heat Performance of Interior Trim Products

Recent trends in automotive interior trim include part consolidation, elimination of painting and lower gloss, all of which require better molding materials, be it general purpose or high heat grades. These requirements, larger and more complex parts and uniform surface appearance, have led the plastics industry to respond with softer flowing grades. These grades provide longer flow length, and better pick up of the mold surface details for the final appearance.

To produce a softer flowing polymer, the polymer viscosity is reduced through material structure engineering. At the same time that these soft flow polymers provided the needed moldability it was found that molding could be accomplished at lower melt and mold temperatures while still achieving the desired surface appearance. Lower molding temperatures make it possible to shorten the cooling cycle and possibly the total cycle time. While the economic benefits of shorter cycle time are readily visible, their realization should be first balanced with the quality of the parts produced under those lower temperature conditions.