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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).

Traditionally, the automotive electrical industry has used thermoplastic polyesters, nylon, and nylon alloys for its primary plastic applications. Current materials-specification trends in this segment are being dictated by 10-year warranty requirements (USCAR's EWCAP tests), higher functionality, increased pin densification, and elevated operating temperatures. This paper will discuss the implications of these trends and discuss materials approaches needed to address both application and manufacturing challenges.

Use of thermoplastic materials for throttle body applications can offer substantial weight, cost, and integration benefits. This paper will discuss the many elements that comprise materials selection, as well as the design and testing of composite throttle bodies. Polyetherimide (PEI), polyphenylene sulfide (PPS), and polybutylene terephthalate (PBT) materials will be discussed and compared as candidates for automotive throttle bodies. The focus areas that will be covered in this paper include: Materials Selection - The criteria for materials selection will be discussed and the properties of candidate thermoplastics compared with key requirements of throttle body applications. Bore and Plate Dimensional Stability and Consistency - The effects of thermal cycling, coefficient of thermal expansion, humidity, and design will be discussed, as well as their relation to bore/plate air leakage.

The increased demands of today's complex automotive connector designs have led to the development of engineering structural analysis tools which address the performance issues of the connector's snap-finger. In designs where hand calculations were once considered the norm in evaluating snap-finger performance, the analysis tools have evolved into the use of finite element techniques which address the high nonlinearity issues of snap-finger disassembly and terminal pull out strength. The structural analysis approaches developed investigate the connector snap-finger performance in reinforced engineering thermoplastics while incorporating the effects of geometric and material nonlinearity in the results. The techniques developed allow for the evaluation of snap-finger performance of prospective connector designs before expensive tooling and prototyping is initiated, providing the benefits of limited tool rework and decreased product development time.

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.

Basic automotive steering wheel armature design has been largely unchanged for years. A cast aluminum or magnesium armature is typically used to provide stiffness and strength with an overmolded polyurethane giving shape and occupant protection. A prototype steering wheel armature made from a unique recyclable thermoplastic eliminates the casting while meeting the same stiffness, impact, and performance criteria needed for the automotive market. It also opens new avenues for styling differentiation and flexibility. Prototype parts, manufacturing, and testing results will be covered.

A model has been developed and implemented at GE Plastics that predicts a material's color shift when weathered. The material's color shift is due to the summation of color shifts from each individual component. By individually measuring the change in each component's optical coefficients upon weathering and using a multiple light scattering model, one can predict the color shift of a material composed of mixtures of these components. The model has been shown to have a standard deviation of 0.4 to 0.9 when predicting color shifts E*, for PC-polyester copolymers, ABS, and ABS/PC blends using an automotive exterior test, SAE J1885, ASTM D 4674, and ASTM D 4459.

An efficient energy absorber (EA) will absorb impact energy through a combination of elastic and plastic deformation. However, the EA is typically coupled with a steel reinforcing beam, which can also elastically and plastically deform during an impact event. In order to design and optimize an EA/Beam system that will meet the specified vehicle impact requirements, the response of the entire assembly must be accurately predicted. This paper will describe a finite element procedure and material model that can be used to predict the impact response of a bumper system composed of an injection molded thermoplastic energy absorber attached to a steel beam. The first step in the process was to identify the critical material, geometric, and boundary condition parameters involved in the EA and Beam individually. Next, the two models were combined to create the system model. Actual test results for 8km/hr.

The consumption of blow molded bumpers for passenger vehicles is increasing, particularly for small to mid-size vehicles. The performance required for bumpers in this class of vehicles varies by geographic region, as “global” vehicles are increasingly specified outside of the United States. For this reason, it is important to understand the impact performance provided by materials that could be blow molded into bumpers for this class of vehicles. This paper will compare the relative performance of polycarbonate/polybutylene terephthalate (PC/PBT) alloys vs. polyolefins for impact protection, weight, and processing performance.

As automakers struggle to meet often conflicting safety, weight, styling, and performance requirements, engineering thermoplastics (ETPs) are making increasing inroads into applications that once were the exclusive domain of metals, glass, and thermosets. A good example of this is in the door systems area, where the performance, design flexibility, aesthetics, parts integration, and lower specific gravity offered by ETPs are allowing highly integrated and efficient modules to be created that, in turn, increase assembly efficiency and reduce mass, part count, warranty issues, and systems costs. This paper will use several case studies on innovative door hardware modules and door panels to illustrate the advantages offered by this versatile class of engineering materials.

Engineering thermoplastics are increasingly being used in automotive applications; many of whose designs are very complex and can pose unique challenges in manufacturing. To help products reach market faster, with better quality and lower cost, use of predictive engineering methods is becoming increasingly common. The purpose of this paper is to review a specific predictive tool: moldfilling analysis. This paper will outline the technology, what is required to use it properly, what issues the technology is capable of addressing, and what other tools are available for addressing advanced issues.

The drive to reduce weight, simplify assembly, and cut total system cost in today's vehicles is relentless. Replacing metal systems with thermoplastics has been of considerable interest in the engineering community. The current generations of engineering thermoplastic resins are enabling the use of plastic systems in demanding underhood applications. Technical data and discussion regarding the materials, design, molding, and assembly of lightweight composite throttle bodies will be presented in this paper. Comparisons with machined aluminum throttle housings are drawn to establish a baseline with the throttle body housing component that is most common in production today. Design flexibility and process simplification are some of the approaches highlighted. Much of the technical information provided in the paper applies to both cable driven mechanical throttle bodies as well as electronic throttle bodies under development.

This paper provides twelve rules to help reduce four key ergonomic risk factors (force, frequency, posture and mechanical stress). These rules were developed to assist individuals who may not have received extensive ergonomic training but who are involved in implementing any changes (major or minor) to manufacturing work stations. This includes changes in task and/or changes in equipment. A complete ergonomic analysis of a work situation is a good idea in most cases, but these rules will avoid many of the commonly occurring problems if applied early in the design or modification of a workplace.

Recent vehicle design trends require bumper systems to be crashworthy under more demanding circumstances, e.g. tighter package space, heavier vehicle mass, and wider rail spans. Meanwhile, pressure to reduce cost and weight of bumpers continues at a time when roles in the supplier community are changing. These factors have combined to increase the importance of optimizing bumper design and material properties for specific platforms. Materials suppliers have responded by developing a range of specialized engineering thermoplastic (ETP) resins that can help meet increasing performance requirements yet also offer the potential for improved manufacturing productivity, significant weight savings, and systems cost reductions. Material suppliers have also increased the level of technical design support provided to OEMs and 1st Tier suppliers.

The first single-piece, injection-molded, thermoplastic, front bumper for a light truck provides improved performance and reduced cost for the 1997 MY Explorer® Ltd. and 1988 MY Mountaineer® truck from Ford Motor Company. Additionally, the system provides improved impact performance, including the ability to pass 5.6 km/hr barrier impact tests without damage. Further, the advanced, 1-piece design integrates fascia attachments, reducing assembly time, and weighs 8.76 kg/bumper less than a baseline steel design. The complete system provides a cost savings vs. extruded aluminum and is competitive with steel bumpers.

Thermoplastic body panels are emerging in the industry as automotive manufacturers seek to design for advanced aerodynamic styling, lower weight, and cost effective vehicles. To best exhibit the advantages of GE thermoplastic resins in these applications, an extensive study has been completed to demonstrate the impact performance of thermoplastic body panels in the field based on the current success with the Buick LeSabre T-Type, Buick Reatta, and the Cadillac Deville and Fleetwood models using NORYL GTX® 910 resin fenders. This study provides a “real life” scenario of the advantages of thermoplastics compared to steel in body panel applications.

Six Sigma methodologies in combination with Lean thinking have made considerable inroads as continuous improvement tools initially in manufacturing and more recently for service and transactional processes. There is considerable interest globally in training professionals on the use and application of these tools appropriate to either operational or transactional areas. It has long been realized that adult learning is at its best when participants are involved in relevant “hands-on” experiments. Six Sigma training has seen the use of class room demonstrations ranging from the use of playing cards, simulations and to the use of sophisticated experiments to illustrate concepts of factorial designs. This paper will focus on a series of simple but modular experiments that were developed over the past two years illustrating the application of all the Statistical tools that are taught as a part of Six Sigma Green and Black Belt body of knowledge.

In a joint effort between Ford Motor Company, Visteon Automotive Systems, Textron Automotive Company, and Dow Automotive the 1999 Mercury Cougar instrument panel (IP) was designed and engineered to reduce the weight and overall cost of the IP system. The original IP architecture changed from a traditional design that relied heavily upon the steel structure to absorb and dissipate unbelted occupant energy during frontal collisions to a hybrid design that utilizes both plastic and steel to manage energy. This design approach further reduced IP system weight by 1.88 Kg and yielded significant system cost savings. The hybrid instrument panel architecture in the Cougar utilizes a steel cross car beam coupled to steel energy absorbing brackets and a ductile thermoplastic substrate. The glove box assembly and the driver knee bolster are double shell injection molded structures that incorporate molded-in ribs for added stiffness.

A compact cassette and compact disc (CD) mechanism mounting bracket was developed for an automotive radio. The bracket, a single die cast magnesium component, offers a light weight, rigid platform for simultaneously attaching both mechanisms to create a simple modular subassembly.

A new front bumper, blow molded from an engineering thermoplastic, is being used to provide full 8 km/h federal pendulum and flat-barrier impact protection, as well as angled barrier protection on a small passenger car. The low intrusion bumper is compatible with the vehicle's single-sensor airbag system and offers a 5.8 kg mass savings compared with competitive steel/foam systems. This paper will describe the design and development of the bumper system and the results achieved during testing.