Jaguar XJ Structures Celstran LFRTs Thermoplastics

Although Jaguar Cars Ltd.'s (Whitley, U.K.) newly redesigned Jaguar XJ has a body made from aluminum rather than sheet steel, the automaker and its automotive systems supplier Automold Ltd. (Gloucestershire, U.K.) used Ticona's (Summit N.J., U.S.A., select 296) Celstran long-fiber-reinforced thermoplastic (LFRT) in the structural components of the door modules and the grill opening reinforcement (GOR). The LFRT material provides not only weight savings, but also enables component integration not possible with aluminum, leading to ease of assembly and savings in manufacturing cost.

Automold, working with Ticona engineers, selected Celstran PPGF30 X293-P11/1X (30 percent long glass fiber-reinforced polypropylene) for the carrier plates in the front and rear door modules. The plates measure 1.0m by 0.7m/39.7 inches by 27.6 inches, and weigh about 1.7 kg/3.7 lb. They are designed to fit precisely into the shape of the vehicle doors, and functional elements such as internal door openers and speakers are built directly into the plate.

Since a 30 to 50 mm/1 to 2 inch border of each carrier plate is visible inside completed Jaguar XJ cars, the color (warm charcoal) and surface texture of the carrier plates had to be aesthetically pleasing. Ticona's proprietary LFRT technology, proper part design and consistent molding assure that the door modules meet strength, color and surface requirements, with no exposed glass fibers.

Ticona aided material development, part design and part development with finite element analyses (FEA), moldflow analyses, extensive material tests and design improvements resulting in reduced component thickness, for weight savings. Door module development work from the first drafts to prototypes took 24 months. Tooling costs were significantly reduced compared to use of aluminum carrier plates in the door modules.

The new GOR is a U-shaped, 1.6m/63-inch wide support that provides for precise positioning of the vehicle's lights, radiator grill, windshield washer reservoir, bumper and front wing. Automold selected Celstran PA66GF50-02-P11/14 (50 percent long glass fiber-reinforced nylon 6/6) for dimensional stability, high-impact strength and temperature resistance up to 180°C/356°F, to withstand paint-bake cycles. The material coefficient of expansion closely matches that of aluminum. Warping of the GOR is less than 1 mm/0.04 inch following critical paint-bake cycles -- less than 0.063 percent across its width.