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Technical Paper

Thinwall Injection Molding for Instrument Panels

2001-03-05
2001-01-1272
As the global auto industry wrote the final chapter on its first century, we saw the average thickness of an automotive instrument panel drop from 3.0 mm-3.5 mm to 2.0 mm-2.3 mm, as found in the 1999 Volkswagen Jetta and Golf. By reducing the wall thickness of the instrument panel, Volkswagen started an industry trend: both OEMs and tiers are investigating technologies to produce parts that combine a lower cost-per-part via material optimization and cycle-time reduction with the superior performance of engineering thermoplastics. The goal is to produce parts that are positioned more competitively at every stage of the development cycle - from design, to manufacturing, to assembly, to “curb appeal” on the showroom floor. The key to this manufacturing and design “sweet spot” is a technology called thinwall - the molding of plastic parts from engineering thermoplastics with wall thicknesses thinner than conventional parts of similar geometry.
Technical Paper

Temperature Measurement Errors in Automotive Lighting

2001-03-05
2001-01-0859
This paper examines a variety of thermocouple and infrared measurement techniques as means of obtaining accurate and consistent temperature measurements within a headlamp system. While measuring temperature is straightforward in principle, in practice, these measurements are fraught with potential error. The paper summarizes a succession of experiments conducted at our Parts Design Center (formerly the Application Development Resource Center) in Pittsfield, MA. These experiments lead to the ability to accurately measure temperature at a given location within a lamp assembly. Using these studies and the resulting transfer functions as a foundation, a Design of Experiment (D.O.E.) is presented which explores the effect of a variety of headlamp design factors on the surface temperature of a headlamp reflector at a given location.
Technical Paper

Design and Development of a Generic Door Hardware Module Concept

1998-02-23
980999
This paper documents the design methodology, part performance, and economic considerations for a generic hardware module applied to a front passenger-car door. Engineering thermoplastics (ETPs), widely used in automotive applications for their excellent mechanical performance, design flexibility, and parts integration, can also help advance the development of modular door-hardware systems. Implementation of these hardware carriers is being driven by pressures to increase manufacturing efficiencies, reduce mass, lower part-count numbers, decrease warranty issues, and cut overall systems costs. In this case, a joint team from GE Plastics, Magna-Atoma International/Dortec, and Excel Automotive Systems assessed the opportunity for using a thermoplastic door hardware module in a current mid-size production vehicle. Finite-element analysis showed that the thermoplastic module under study withstood the inertial load of the door being slammed shut at low, room, and elevated temperatures.
Technical Paper

Rationalizing Gas-Assist Injection Molding Processing Conditions

1995-02-01
950562
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.
Technical Paper

Understanding the Mechanical Behavior of Threaded Fasteners in Thermoplastic Bosses Under Load

1996-02-01
960293
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).
Technical Paper

Optimizing Parts and Systems Integration with Engineering Thermoplastics to Meet the Challenges of Future Automotive Door Systems

1997-02-24
970144
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.
Technical Paper

Why Thermoplastic Door Hardware Systems Make Economic Sense Now

1997-02-24
970143
Engineering thermoplastics are widely used in a variety of automotive components systems because of their excellent balance of mechanical performance, design flexibility, aesthetics, parts integration, and low specific gravity. This combination of properties allows for the creation of highly integrated modules, which can increase assembly efficiency and reduce mass, part count, warranty and ergonomic issues, and systems costs. As a result, the use of engineering thermoplastic materials can enhance market competitiveness at a time of increased global competition. To evaluate the economic advantages of polymers in a specific vehicle system, a design for assembly (DFA) case study was conducted with the goal of determining the variable system cost case for a generic thermoplastic door module system vs. conventional-build door systems based on assembly savings gains. This paper will describe the study and show the results achieved.
Technical Paper

Rationalization of Processing Conditions for Gas Injection Molding

1994-03-01
940620
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.
Technical Paper

Correlation of Finite-Element Analysis to Free-Motion Head-Form Testing for FMVSS 201U Impact Legislation

1997-02-24
970163
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.
Technical Paper

Thermoplastic Materials for Throttle Body Applications

1999-03-01
1999-01-0316
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.
Technical Paper

Prototype Design and Testing of a Thermoplastic Steering Wheel Armature

2007-04-16
2007-01-1218
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.
Technical Paper

Two-Shot and Overmolding Technology for Automotive Applications Using Engineering Thermoplastics

2002-03-04
2002-01-0274
There are a multitude of opportunities to utilize two-shot or overmolding technology in the automotive industry. Two-shot or overmolding a thermoplastic elastomer onto a rigid substrate can produce visually appealing, high quality parts. In addition, use of this technology can offer the molder significant reductions in labor and floor space consumption as well as a reduction in system cost. Traditionally, two-shot applications were limited to olefinbased TPE's and substrates, which often restricted rigidity, structure and gloss levels. With the development of thermoplastic elastomers that bond to engineering thermoplastics, two-shot molding can now produce parts that require higher heat, higher gloss and greater structural rigidity. This paper will outline engineering thermoplastics that bond with these new elastomers, discuss potential applications, and review circumstances that offer the best opportunity to call upon the advantages of two-shot and overmolding technology.
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