The Swiss company Quardrant PlasticsComposites (QPC) has introduced a range of lightweight reinforced thermoplastic composites (LWRT), including sheets and preforms, under the trade name Symalite. Due to the low density of LWRT composites, the hardness per unit weight is higher than that of conventional glass fiber felt reinforced thermoplastic (GMT) sheets, while this material is compatible with metals, GMT and conventional PP and nylon long fiber thermoplastics ( LFT) composites offer the advantages of reduced weight, more flexible design and lower cost, making them an ideal replacement for lightweight GMT composites. According to QPC, the new composites are easy to adhere to fabrics, gauze, foams, dry powder coatings and sturdy PP surfaces by using low-pressure forming technology, making it easy to mold. In addition, an adhesive film can be used to bond the Symalite material to the sheet coated with aluminum coil. Currently, QPC is considering the use of such an aluminum/plastic laminate for the manufacture of automotive roof moldings. . Symalite composites are suitable for the manufacture of automotive underbody shields, load-bearing panels, roof linings, door trims, luggage racks, roof moldings, engine covers and rear trunk lids. Novel production process Typically, the GMT composite sheet is a composite of PP powder and chopped glass fibers. Unlike the manufacturing process of GMT composites, QPC's LWRT lightweight composites use dry process technology used in fabric production to produce hairs blended with PP and fiberglass. In the continuous production process, the blended hair is heated to a temperature higher than the melting point of the PP, and then laminated to the surface layer of the adhesive film or the pure PP film, and finally cut into a blank. Considering the fact that the resin is separated from the fibers when the shredded glass fiber molded parts are used, the company chose a glass fiber of 78 mm in length to form a 3D substrate that prevents separation. QPC claims that this process allows the glass fibers to be well distributed in the PP while also providing good control of the bulking process of the material. When the sheet is heated, it expands and expands to a thickness of five times because the glass fiber is stretched out from the consolidated billet in a compressed state. Therefore, QPC adjusted the bulkiness of the sheet by changing the content of the glass fiber. Generally, when the glass fiber content is high, the bulkiness is increased and the density is decreased, so that the specific hardness (hardness to weight ratio) of the final product is increased. When making products with Symalite blanks, QPC used a low pressure "hot stamping" process. The process uses a double-sided aluminum plate mold, which is said to have much less cost and development cycle than steel molds. After using this mold, the billet produces only a small deformation during the forming process, and the final product produced has different strengths at different wall thicknesses. Thick places usually have high hardness, while thin places have hardness. Not high but tensile strength is high. In Germany, QPC is able to produce sheets with a glass fiber content of 20% to 60%. At present, products with a glass fiber content of 40% to 55% have been commercialized. Among them, the 40% glass fiber content sheet is suitable for the manufacture of the underbody shielding device, the load bearing plate and the openable roof; the 55% glass fiber content sheet is suitable for the manufacture of the roof lining. The standard sizes of these laminates are 22in, 30in, 45in and 90in (1in = 25.4mm), although they can be customized as required. Business application success Seeber AG, based in Mannheim, Germany, used the Symalite composite to create a vehicle floor shield for BMW, the first successful commercial application of the material. This underbody shield consists of four Symalite parts with a 40% glass fiber content. Since they are laminated from two faces with an unreinforced PP film, their impact resistance, wear resistance and moisture resistance are improved. Compared with the previous GMT components, its weight is reduced by 30%, the drag coefficient is also reduced, and this product also has a good sound-absorbing function. According to the introduction, the mold for manufacturing the device is a multi-cavity mold comprising a 4-part assembly with an auxiliary mechanical device for drilling a hole in the molding process. When a 79 in x 73 in (1 in = 25.4 mm) blank is fed into the multi-cavity mold, the molding of the above four components can be completed in a working cycle of less than 60 seconds. Compared to BMW's original underbody shielding, Seeber AG's Symalite composites are not significantly reduced in weight, but their greatest advantage is the ability to take advantage of the different thicknesses of the product, such as The thickness of the central part of the product is 4mm, which optimizes the specific hardness value and has the function of noise reduction. The thickness of the periphery is only 1mm, which improves the joint force and seal strength. Currently, QPC has begun research and development work on its composite materials for exterior panels for automobiles and off-road vehicles. Their research focus is on attaching a pre-sprayed aluminum layer to the core of the SymaLite material to make a car roof molding. Since the coefficient of thermal expansion (CLTE) of the aluminum lining is almost the same as the CLTE value of the SymaLite composite, the bending deformation of the article can be reduced. 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