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Thermoplastic polyurethane/ABS blends are being developed by The Dow Chemical Company to meet the high performance requirements for flexible bumper fascia. Features of these blends include paintability without priming, excellent low temperature impact after painting, good heat resistance, and lower specific gravity than other high performance thermoplastic materials. Thermoplastic polyurethane/ABS blends also have excellent flow properties, which will allow large, complex parts with thin walls to be molded easily.

A family of thermoplastic Polyurethane (TPU) blends is being developed to compete in the flexible automotive bumper fascia market. Features of these blends include paintability without adhesion promoter or primer, ease of processing, outstanding low temperature impact strength, good mar resistance, and excellent property retention upon recycling. Laboratory and application performance data indicate that painted TPU/ABS Blend XT2100 regrind can be incorporated up to a 25% level into flexible thermoplastic fascia without sacrificing impact resistance.

The magnesium alloy AE42 (nominally a 4 % aluminum, 2 % rare earth alloy of magnesium) is a developmental die cast alloy with good strength and creep resistance at elevated temperatures. Standard salt spray corrosion tests have been used with controlled purity AE42 die castings to define the critical iron, nickel and copper contaminant levels below which excellent corrosion performance can be obtained. As previously observed with the magnesium alloys AZ91, AM60, and AS41, the critical iron content is dependent upon the manganese content of the alloy. While the iron:manganese tolerance for AE42 is about the same as that of AM60, the tolerance for the nickel and copper contaminants is greater than that of AZ91. When each of these contaminants is less than the critical level, the salt spray performance was equal to or better than die cast 380 aluminum and cold rolled steel.

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.

The objective of this paper will be to review a novel recycle process involving Structural Reaction Injection Molding(SRIM) which enables a variety of coarsely ground plastic recycle materials to be incorporated into the molded part. What makes this approach novel, is that flexural modulus of the fabricated parts are actually increased when the recycled granulate is employed in the part. This paper will present data for the recycle of a variety of automotive parts, including painted fascia, door skins, covered interior door panels, armrests and instrument panels along with composite bumper beams into the SRIM recycle core process. Resulting part economics will be reviewed along with potential applications to utilize this technology.

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.

Standard salt spray corrosion tests have been used with controlled purity AM60 castings to define the critical iron, nickel, and copper contaminant levels below which excellent corrosion performance can be obtained. As previously observed with the AZ91 alloy, the iron solubility and the corrosion tolerance limit for iron are dependent upon the manganese content of the metal. The zinc free AM60 alloy has a somewhat lower tolerance for all three of the critical contaminants when compared to AZ91, but when the three contaminants are below their individual tolerance limits, the salt spray performance is again equal to or better than die cast 380 aluminum and cold rolled steel.

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.