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Automotive engineers and designers are working to develop pillar-trim concepts that will comply with the upper interior head-impact legislation, FMVSS 201U. However, initial development cycles have been long and repetitive. A typical program consists of concept development, tool fabrication, prototype molding, and impact testing. Test results invariably lead to tool revisions, followed by further prototypes, and still more impact testing. The cycle is repeated until satisfactory parts are developed - a process which is long (sometimes in excess of 1 year) and extremely labor intensive (and therefore expensive). Fortunately, the use of finite-element analysis (FEA) can greatly reduce the concept-to-validation time by incorporating much of the prototype and impact evaluations into computer simulations. This paper describes both the correlation and validation of an FEA-based program to physical free-motion head-form testing and the predictive value of this work.

Because it is common to attach plastic parts to other plastic, metal, or ceramic assemblies with mechanical fasteners that are often stronger and stiffer than the plastic with which they are mated, it is important to be able to predict the retention of the fastener in the polymeric component. The ability to predict this information allows engineers to more accurately estimate length of part service life. A study was initiated to understand the behavior of threaded fasteners in bosses molded from engineering thermoplastic resins. The study examined fastening dynamics during and after insertion of the fastener and the effects of friction on the subsequent performance of the resin. Tests were conducted at ambient temperatures over a range of torques and loads using several fixtures that were specially designed for the study. Materials evaluated include modified-polyphenylene ether (M-PPE), polyetherimide (PEI), polybutylene terephthalate (PBT), and polycarbonate (PC).

Gas-assist injection molding is a relatively new process. It is an extension of conventional injection molding and allows molders to make larger parts having projected areas or cross sectional geometries not previously possible using existing equipment. However, controlling the injection of the gas has been a concern. The plastics industry is attempting to establish logical techniques to set up and rationalize processing conditions for the method. Although gas injection equipment permits a number of adjustments, an optimum processing window must be established to provide control and repeatability of the process to mold consistent, acceptable parts. This paper describes a strategy and equipment for rationalizing and accurately controlling gas injection processing conditions that are applicable regardless of the type of molding machine or processing license a molder is using.

The gas injection molding process created a great deal of interest when it was first introduced, especially on the part of the automotive plastics industry. The process allows injection molders to make larger parts with increased rigidity at lower clamping pressures. This, in turn, allows parts to be molded that have not previously been able to be created. However, the process has been hampered by problems. First and foremost have been the numerous patent infringement suits and licensing difficulties that have retarded the spread of the technology in the United States. Second, technological problems - such as controlling the seemingly erratic nature of the gas - have also been an issue. As with any new molding technology, the plastics industry is still attempting to establish logical techniques to set up and rationalize processing conditions for the method.

When GE Plastics entered the multi-process multi-material arena with the construction and installation of Alpha I in its Pittsfield, Mass. headquarters, it recognized that if plastics are to continue to provide revolutionary products, the industry must expand its thinking beyond current single process applications. Multi-process parts must be developed to demonstrate to the automotive industry a new generation of applications. The purpose of this paper is twofold: to explain the value of multi-process multi-material technology and to present an engineering analysis of the system which addresses design and processing questions.

Glass fiber reinforced bumper beams are being used on increasingly more automobiles due to the weight and energy management advantages the materials have over steel. Current bumpers are manufactured using basically three fiber orientations or combinations thereof: 1) Random, chopped and continuous 2) Unidirectional, continuous along the length of the beam 3) 0.90, continuous on the length and perpendicular, woven For the purpose of this paper, the composite used for all FEA models and sample moldings is a 40% continuous glass fiber reinforced, polypropolene resin based, sheet stampable thermoplastic. It is possible to assume that the results can be generatalized to other composites. The finite element analysis found that significant increases in performances were achieved over the conventional fiber orientations.

Historically, plastic has been the material associated with dramatic parts consolidation. Currently, part consolidation has been limited by the individual limitations of the various plastic processing techniques. In order for plastics to continue providing revolutionary products, we must expand our thinking beyond the current single process applications and allow our creativity to develop multi-process parts that will show the industry a new generation of applications. The automotive industry is demanding revolutionary new technology. Alpha I, GE Plastics' response to this revolution, is the next generation of processing equipment. At the K-89 Show in Dusseldorf, West Germany, the Alpha I processed and GE Plastics introduced a prototype integrated bumper beam and fascia system. The integrated bumper system is an impact beam compression molded from AZDEL® composite with a fascia injection molded from XENOY® resin produced as one unit in a 4.0 minute cycle.