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As the composites industry struggles to give a competitive edge to customers while continuing to be safe, efficient and good product stewards, the industry must continually reevaluate older processes with new materials. Years ago sheet molding compound (SMC) was the only way to achieve Class “A” surfaces. In the recent past, new low profile additive chemistry has allowed Class “A” surfaces to be made with the “old” resin transfer molding (RTM) process. Now, breakthrough resin technology allows Class “A” surfaces with even the older spray up process; and the industry is reinventing the SMC process with crystalline resin that can be compression molded into Class “A” surfaces at less than 200 psi. This paper will discuss current resin technology changes as well as the processes and tooling changes that have allowed these technology breakthroughs. Discussion will also center on the strengths and weaknesses of each material and process.

With the Elan's launch, Lotus is moving into a new era of low-volume production. By the middle of the next decade, a maximum of 3000 a year will be produced at Hethel and it was these requirements, combined with a desire for more design freedom, that led Lotus to carefully examine its current VARI (Vacuum Assisted Resin Injection) process and develop a unique, flexible system for the Elan. It was decided to develop a manufacturing process to employ a larger number of separate panels to allow future design freedom. The aim was to jig assemble panels which would allow accurate and consistent control of the complete assembly. Evaluation of alternative materials and processes for body panel manufacturing began in 1987, leading to the conclusion that the Lotus patented VARI process was still the most cost effective for the new car.

The purpose of this paper is to outline the current state of polyurethane bonding technology in the transportation industry. The paper focuses on the strengths and limitations of this technology and the reasons for its long-term success in the market place. Significant advances have been made in the range of end use applications for polyurethane structural adhesives. The introduction of the new General Motor's Lumina, Silhouette, and Transport mini vans has created the largest assembly line use of structural adhesive to bond SMC body panels to date. Molders and manufacturers of more traditional SMC assemblies have made noteworthy improvements in productivity with fast cure bonding cycles and simplified production processes using polyurethane technology. Auto makers have continued to capitalize on the cost and performance benefits of bonded composite body vehicles for specialty niche markets.