Class “A” - Low Pressure Materials for Low Pressure Processes

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.