An instrument panel retainer in the 2014 Jeep Cherokee sports utility vehicle demonstrates the potential for thinwall molding with long glass fiber polypropylene.
The typical wallstock on conventional injection-molded olefin resin is 2.5 mm to 4.0 mm. The Cherokee IP retainer is just 2 mm, resulting in a 27 percent weight reduction and a 30 percent reduction in molding cycle times. According to Matt Delaney of SABIC, which supplied the PP, the 30 percent glass-reinforced compound provides the required stiffness, strength, and impact performance to meet interior safety requirements. Overall plastics use was cut by more than 2.5 million pounds over the life of the vehicle’s program. Costs were cut $3 per vehicle.
Not surprisingly, fiber orientation is the key to making this approach work. Advanced fiber-orientation modeling was used to reduce warpage during mold design.
The part won the top award in the body interior category in this year’s Society of Plastics Engineers Automotive Innovation Awards, which were announced Nov. 6 in a banquet in Novi, Mich.
• Tier Supplier/Processor: Intertec Systems
• Material Supplier / Toolmaker: SABIC/Windsor Mold Group
• Material / Process: Stamax 30YK270 PP/Thinwall injection molding