Considerations in Material, Part, and Process Design for Downgauged RRIM Applications 2003-01-0209
To address the automotive industry's initiative to maximize the utility of each component by decreasing both weight and cost to improve the performance and value of its products, it is logical to try to minimize the thickness of any part whose main function is ostensibly decorative. A example of such a candidate part on the vehicle would be the fascia and body side claddings. The fascia and claddings of vehicles do provide some impact resistance and resiliency functionality to vehicles, but more and more, the energy management functionality is being taken on by improvements in the engineering design and support systems behind the exterior part. The function of these exterior parts then, is, to a large degree, to be aesthetically pleasing when painted, and maintain their high quality fit and finish over the life of the vehicle. These applications are therefore justifiably subject to investigations into the reduction of their wallstock.
Downgauging, or reducing the thickness of any part, regardless of the material is being used in a particular application, is not necessarily a trivial matter. Under the wise axiom that one “never gets something for nothing”, some part design, material architecture, assembly system, and mould processing considerations must be investigated. This same type of critical engineering thought holds when designing and manufacturing parts using the RRIM process. Part thickness is an integral part of the design criteria for any part, and it has a dramatic effect on several key parameters in the RRIM process and part manufacture. The purpose of this paper is to introduce and explore some of these parameters, and to outline the engineering considerations that must be made in the design and execution of a successful thinwall RRIM program.