Optimization of the Compression (Injection/Compression) Molding Process Using Numerical Simulation

The increasing requirements on auto makers to reduce both the cost and weight of passenger vehicles as well as meet ever more restrictive government regulations make the use of fiber reinforced plastics very attractive. In particular, the use of thermoset composites, such as SMC and BMC, have been used for years by the major auto makers to produce high quality, strong, stiff, and lightweight body panels. Increasingly, it is being used for more structural components throughout the vehicle. However, the use of fiber filled thermoset composites is not limited to the automotive industry. It is also extensively used in electronic components, sports equipment, and general consumer goods. Accordingly, the need to be able to design these molded parts and to predict the complex behavior during manufacture and in service is paramount to reducing the time from concept to production. This paper introduces a finite element based simulation program that allows the entire molding process, including mold filling, fiber orientation, heat transfer, cure, residual stress and warpage, to be simulated on the computer rather than by experimental prototyping. The software allows designers and engineers to determine product performance during the design stage before the tooling needs to be manufactured. Then, by modifying the design and process with the computer, part optimization can be accomplished prior to building the mold. The paper discusses the models and methods implemented by the simulation program along with the accompanying assumptions. The results of the simulation are compared with experimental results for a variety of parts. This paper then highlights a case study of an injection/compression molded component showing how the simulation can be used as a design optimization tool.