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Technical Paper

Novel Acoustical Polyolefin Foams

2001-04-30
2001-01-1556
Novel acoustical materials have been developed. The materials are thermoplastic foams extruded from blends of a polypropylene (PP) resin with an ethylenic polymer resin. One material is an open-cell sheet product made from a blend of a PP resin and a polyolefin elastomer (POE). Another is a large-celled plank foam of substantially closed-cell structure made from a blend of a polypropylene resin and a low density polyethylene (PE) resin. The foam materials are of lightweight, hydrophobic, dust free, recyclable and withstand the temperatures prevailing in automotive uses.
Technical Paper

Separation of Non-Metallic Contaminants in Fluxless Melting and Refining of Magnesium Alloys

2000-03-06
2000-01-1125
Recent growth in automotive applications of magnesium die cast alloys has made the refining and recycling of magnesium scrap a key issue for the automotive and magnesium industries, if growth is to continue. Today, with only a few exceptions, commercially refined and recycled alloy is produced using a variety of flux-based processes. However, fluxless refining, has been the focus of growing interest, particularly for the in-house refining of scrap by the die cast producers. This paper summarizes the results of a study conducted to better understand the behavior of non-metallic contaminants in scrap melts and the requirements for their separation, using argon sparging. Brightness measurements were used to experimentally determine the distribution of non-metallic contaminants within scrap melts both before and after argon treatment.
Technical Paper

Performance Comparison of Plastic Composites with Metals for Vertical Body Panel Applications

1999-03-01
1999-01-0848
In 1998, approximately 57,000 Tonnes of plastic composites were utilized as body panels on cars and trucks in North America. Three material types, generically labeled SMC, RIM and Thermoplastic are vying to carve a market niche from steel which dominates the market place with an estimated volume of 1 million Tonnes per year. Since plastic body panels have higher material costs but lower tooling costs, they are primarily utilized when build volumes are less than 200,000 vehicles per year or specific composite performance capabilities are demanded. This paper reviews the various performance parameters required of a body panel material and the relative strengths of Aluminum, RIM, SMC, Steel and Thermoplastics to meet these demands. A decision making process is utilized which allows for a comparison between the different materials. Since cost is so critical, it is left as an independent variable.
Technical Paper

ELPO-Capable Polyurea RRIM Advancements for Automotive Body Panels

1998-02-23
980987
Continued development of Reinforced Reaction Injection Molding (RRIM) polyurea polymers for toughness, blister resistance and large-part processing as exterior vertical body panels has launched ELPO-compatible exterior outers into automotive assembly-line operations. This allows automotive OEM design to take advantage of the unique molding shapes for side outers and fenders while reducing weight, assembly (DFA) and time/operations costs (DFM). Polyurea RRIM body panels have been successful in meeting the demanding auto industry requirement for lightweight, damage-resistant exterior outer panels as an economical alternative to steel. Design freedom advantages, low prototype cost and tooling savings through predictive modelling have allowed the commercial use of RRIM body panels. This high-temperature-resistant polyurea RRIM composite allows on-line painting, including passing through the steel corrosion protection primer (E-coat) cure environments.
Technical Paper

The Effect of Non-Metallic Inclusions on the Properties of Die Cast Magnesium

1997-02-24
970331
The effect of non-metallic inclusions (NMIs) on the properties of die cast magnesium was investigated. NMI content was quantified by a newly developed light reflectance technique. The mechanical properties of optimized AM60B test bars were found to decrease at high inclusion levels. Low inclusion levels did not statistically reduce the mechanical properties of AM60B as compared to virgin metal. Argon-refined AM60B displayed mechanical properties that were indistinguishable from virgin alloy. AZ91D test plates were die cast at various cleanliness levels. After salt spray testing, it was found that the surface quality of the castings was slightly degraded at high NMI levels. The general corrosion performance was also affected, but paint adhesion was relatively unaffected. At high NMI levels, the corrosion performance was still better than 380 A. Machinability of the AZ91D test plates was quantified by measuring tool wear and cutting forces.
Technical Paper

Instrument Panel Design Architectures - Relation to Structure, Materials and Process

1997-02-24
970728
The increase in instrument panel design and functional performance requirements has resulted in a variety of structural architectures that have been utilized in different passenger vehicles, vans, and light trucks. Each architecture can be designed and engineered to meet corporate and federal requirements using different levels of integration, functionality consolidation, and assembly simplification. The present paper reviews three basic IP design architectures, i.e., traditional, hybrid, and structural, and discusses the performance requirement-functionality matrix in each case. Emphasis is given at explaining the role components play in the different architectures, defining their contribution to static, dynamic and crash performance and their relation to the overall assembly process and sequence. Performance and functionality requirements are linked to basic material characteristics that guide material selection for achieving design targets.
Technical Paper

SPS Crystalline Polymer: A New Material for Automotive Interconnect Systems

1997-02-24
970305
Syndiotactic Polystyrene (SPS) is a new semi-crystalline polymer under development by Dow Plastics. The material is completely different from conventional styrenics in structure, physical properties and synthetic method, and represents the basis for an entirely new family of materials based on crystalline polystyrene. SPS has a melting point of 270°C (520°F) combined with excellent resistance to moisture and automotive fluids. Additionally, SPS products exhibit exceptional electrical performance and competitive toughness and stiffness. A wide range of products have been formulated for specific applications including impact-modified and glass-reinforced grades. This paper was designed to discuss the performance attributes of SPS as they relate to use of this material in automotive, interconnect systems where a combination of heat resistance, chemical resistance, dimensional stability and enhanced processability are required.
Technical Paper

A Business View of the Recycling of Plastics from Durable Goods

1996-02-01
961044
The recycling of plastics from end of useful life durable goods continues to evolve as an issue. Recycle strategies need to be based on a careful understanding of sustainability for both the environmental and business domains. The definitions and processes utilized in a recycle program can dramatically affect the economic structure. These recycle programs need to be carefully constructed to minimize cash costs. There is an emerging industry, recyclers, who may become an important link in the recycle supply chain.
Technical Paper

Hot Chamber Diecasting of Magnesium Alloy AM50A for Automotive Interior Structural Components

1996-02-01
960416
Increased requirements for crash energy management in automotive interiors have led to increased application of magnesium alloy AM50A. Successful integration of this new alloy with hot chamber diecasting process technology requires substantial adjustment and attention to processes and practices. This paper details the conversion of magnesium AZ91D steering column diecastings to high ductility structural alloy. Description is given of the changes made to foundry practices, casting parameters, process compliance monitoring, and hot end component management. The resulting improvements allow production of components comparable to the traditional alloy in manufacturing process demands while offering improved ductility and impact strength.
Technical Paper

Engineering Development and Performance of the Chrysler Dakota Fully-Integrated Thermoplastic Instrument Panel

1996-02-01
960399
A fully-integrated thermoplastic structural instrument panel (IP) system will be implemented on Chrysler's Dodge Dakota Truck Platform. The structural IP consists of a three-piece monocoque thermoplastic injection molded structure that replaces the traditional retainer, air delivery ducts, steel beams and reinforcements typically used in IP designs. Ribbed thermoplastic bolster systems have been incorporated as part of the energy management system. The structural IP provides the required stiffness to satisfy noise, vibration, and harshness (NVH) quality targets and the necessary strength and rigidity to effectively meet FMVSS No. 208 requirements for managing occupant and passenger air bag (PAB) deployment loading during 48 km/h (30 mph) frontal crashes.
Technical Paper

Design Advantages and Benefits of the Chrysler Dakota Fully Integrated Thermoplastic Instrument Panel

1996-02-01
960398
Today's interior systems design engineer has been challenged with providing significantly lighter, simpler and more cost-effective instrument panel (IP) design solutions, while simultaneously meeting rigorous occupant protection and quality standards. These issues provided the motivation behind the fully-integrated structural instrument panel design developed for Chrysler's Dodge Dakota Truck Platform. This total system design approach greatly depends on the stiffness and ductility of the engineering thermoplastic substrate and cross-sectional design for managing the energy of unrestrained occupants during frontal collisions. The structural IP consists of a fully integrated, three-piece monocoque thermoplastic structure that replaces the traditional retainer, air delivery ducts, steel beams and reinforcements typically used in IP designs.
Technical Paper

Structural Design and Evaluation of Composite Closure Systems for Under-the-Hood Applications

1995-02-01
950486
The opportunity for composites in engine closure systems such as valve covers, oil pans, and timing belt covers is expanding rapidly. The primary driving forces are lighter weight finished components, integrated designs, improved isolation of engine noise, improved materials systems, and matured manufacturing processes for composite materials. Thermoset-based composite materials, particularly those based on high-temperature resistant epoxy vinyl ester matrices, offer improved performance with respect to thermoplastic and thermoset polyester-based composites and can be manufactured using different processing methods. This paper presents the current state-of-the-art design, engineering and optimization techniques for engine closure systems. The performance requirements of different systems such as valve covers and oil pans are explained in detail. Techniques for long-term structural stiffness evaluation, vibration performance assessment and noise transmission estimation are described.
Technical Paper

Material Selection Guidelines for Structural Instrument Panel Applications

1995-02-01
950642
Structural instrument panels are an excellent alternative to traditional constructions since they can provide substantial part consolidation, weight reduction, tool and cost savings, and manufacturing and assembly simplification. In structural panels, the main energy absorbing element for decelerating an unrestrained occupant is the plastic integrated retainer-structural duct. The role of the components in the instrument panel needs to be clearly understood for adequately engineering the system and properly selecting the polymeric material for optimum system performance in the different operating environments. The present paper discusses the performance of the structural instrument panel, the engineering and design requirements, and provides guidelines for selection of materials.
Technical Paper

The Origin of Microporosity in Magnesium Alloy AZ91

1994-03-01
940776
The persistent occurrence of microporosity defects in AZ91 castings has made it difficult to consistently produce sound parts. Earlier work established that dissolved hydrogen gas causes microporosity defects in AZ91; however, the exact role of hydrogen in the nucleation and growth of microporosity was not determined. In this paper, the behavoir of dissolved hydrogen gas in elemental magnesium, AZ91 alloy, and liquid binary Mg/Al alloys was studied. The results show that during the last stages of solidification, hydrogen gas is rejected from the Mg17Al12 intermetallic compound to assist in the nucleation and/or growth of microporosity.
Technical Paper

Designing Composite Engine Sealing Components

1994-03-01
940555
The market for composite engine oil sealing components, such as valve covers and oil pans, continues to expand, replacing traditional metal stamping and die casting materials. As the market for these composite components grows, so must the understanding of the material performance characteristics and the relationship of these characteristics to the design of the part. Unlike metals, composites are viscoelastic in nature, exhibiting time-temperature dependant properties. Therefore, the traditional design approach utilizing static property data to predict long-term performance under load and over a wide temperature range will not sufficiently characterize the nonlinear property response of polymeric-based composites. A robust composite sealing design requires complete materials characterization, including long-term creep performance as a function of temperature, loading, and cycling.
Technical Paper

New Developments in Low Density RIM Composites for Interior Trim

1994-03-01
940703
The use of low density reinforced Reaction Injection Molded (RIM) substrates for covered interior automotive articles continues to increase globally. Reduced party mass, consolidation of manufacturing steps (labor), and the use of aluminum tooling, instead of steel, are cited advantages that LD-RIM offers when compared to traditional wood based and thermoplastic materials. Two RIM processes are successfully being used to produce covered interior door panels. Low density structural RIM (LD-SRIM), utilizing conventional RIM equipment, involves the placement of a pre-cut fiberglass mat in the tool cavity prior to open-pour injection of the 2-stream liquid urethane components. Low density reinforced RIM (LD-RRIM), utilizing lance cylinder RIM equipment, incorporates reinforcing fibers, such as milled fiberglass or wollastonite, in the liquid resin component. The liquid resin containing reinforcing filler is injected with the isocyanate component into a closed mold.
Technical Paper

Polymeric Reflective Materials for Automotive Applications

1993-03-01
930177
A highly reflective polymeric sheet has been invented which has a metallic appearance but contains no metal. The material can appear chrome-like, or be designed to transmit and reflect light for novel lens applications. The absence of metal waste streams and volatile organic emissions gives this technology significant environmental advantages over competitive methods of bright work or reflector fabrication. This unique optical material is non-corroding, and has the low thermal and electrical conductance of plastic. It is produced by coextruding a large number of alternating layers of polymers having a refractive index difference. This technology offers new degrees of freedom for light control in many applications including lighting reflectors, lenses, display panels, decorative trims, and energy management.
Technical Paper

Syndiotactic Polystyrene: A New Polymer for High Performance Automotive Applications

1993-03-01
930088
Syndiotactic potystyrene (SPS) is a new semi-crystalline polymer under development by Dow Plastics, a business group of The Dow Chemical Company. The material is differentiated from conventional styrenic polymers in terms of microstructure and physical properties and represents the basis for an entirely new family of materials derived from crystalline polystyrene. SPS exhibits excellent thermal performance with a melting point of 270° C (520° F) combined with resistance to moisture and automotive fluids. Products produced from SPS demonstrate exceptional electrical performance, low specific gravity, competitive toughness and high modulus relative to other semi-crystalline engineering polymers. A wide range of products have been formulated including impact modified and glass reinforced resins for use in specific markets.
Technical Paper

A Recyclability Evaluation of Automotive Interior Components

1993-03-01
931029
The American public's desire to recycle and the predictions of future recycle mandates are motivating automotive OEMs and plastic suppliers to address the recycling of plastic materials. As a result, the OEMs and plastic industry groups have asked resin suppliers, automotive dismantlers and reprocessors to assist them in studying and developing solutions for the recovery of post-consumer automotive plastics and recycling those materials back into automotive applications. The Dow Chemical Company has been a participant in plastic industry sponsored projects and has initiated numerous research and development activities involving the recycling of automotive thermoplastic and thermoset materials, as well.
Technical Paper

Interdependence of Hydrogen and Microporosity in Magnesium Alloy AZ91

1993-03-01
930754
The relationship between hydrogen gas and microporosity in magnesium alloy AZ91 was quantified, refuting the belief that hydrogen levels less than the maximum solid solubility are of no detriment. Sand castings were made from melts containing measured levels of hydrogen gas, and the amount of porosity was determined by density measurements. At concentrations below the maximum solid solubility, it was established that the amount of microporosity is directly proportional to the gas content. This supports the premise that dissolved hydrogen gas provides nucleation sites for microporosity, and that it is useful to remove all gas to achieve porosity-free cast parts.
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