ABSTRACT
Continued development of Reinforced Reaction Injection Molding (RRIM) polyurea polymers for toughness, blister resistance and large-part processing as exterior vertical body panels has launched E-Coat-compatible exterior outers into automotive assembly-line operations. This allows automotive OEM design to take advantage of the unique molding shapes for side outers and fenders while reducing weight, assembly (DFA) and time/operations costs (DEM). Polyurea RRIM body panels have been successful in meeting the demanding auto industry requirement for lightweight, damage-resistant exterior outer panels as an economical alternative to steel. Design freedom advantages, low prototype cost and tooling savings through predictive modelling have allowed the commercial use of RRIM body panels. Having these exterior body panels pass through the E-Coat lines with the complete steel assemblies also avoids costly space and time requirements, as well as “add-on” body shop space.
Since late 1998, SPECTRIM* HH390 has had outstanding success as a SMC and steel replacement for exterior body panels on two GM truck programs. The experience of bringing a part from CAD (computer aided design) drawings through molding of the part, to body-in-white assembly, through the steel treatment process including e-coat ovens which reach 205°C, and the painting and assembly process gave us the direction for product enhancements that would benefit both the OE and Tier 1. This high-temperature-resistant polyurea RRIM composite allows on-line painting, including passing through the steel corrosion protection primer (E-coat) cure environments. The temperatures range from 175 – 200°C in the oven. This configuration of the RRIM panels, riding with the steel assembly, results in a high quality and consistent finish. RRIM panels also produce a high gloss and DOI product with long-term durability and ease of in-line repair. Significant development work to meet these diverse demands of the design, manufacturing and assembly process has resulted in polyurethane polymer advancements. This paper discusses both die learning process and advancements to meet future body panel requirements.
