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PC/ABS blends have been used with much success in energy management applications for the last 10 years. These systems are typically injection molded; however as blow molding technology advances, a re-examination of applicable applications is warranted. The attributes of the two molding techniques will be compared in a technical manner to illustrate which process delivers the most cost effective solution for automotive interior impact components. Material morphology and property consistency, energy management capability, weight savings, and total systems costs will be explored. Both fabrication techniques will be examined using FEA simulations to demonstrate energy management and weight savings. High magnification microscopy will depict part microstructure for both techniques, illustrating differences in morphology and rubber phase orientation in PULSE* Polycarbonate-Acrylonitrile-Butadiene-Styrene Blends (PC/ABS).

The blow molded knee bolsters on the 1996 Chevrolet Astro and GMC Safari vans are the first blow molded parts used on an interior structural application. These knee bolsters also meet FMVSS 208 requirements. The one-piece bolsters, used on both the driver's and passenger's sides of the vehicle reduced cost by $4.00 and weight by 40% per vehicle compared with two-piece, steel-reinforced plastic knee bolsters. Additional savings were realized in tooling cost reductions of $300,000 and a development time that was shortened by 64 weeks. Part testing was also reduced to the tunability of the process. Aesthetic concerns of matching adjacent injection molded and vinyl parts were also met. This paper discusses the combination of material, processing and tooling technologies that made this program a success.