The largest automotive component ever molded with the MuCell microcellular process—and also the first instrument panel ever molded with this process—won the Grand Award at the 2011 SPE Automotive Innovation Awards Competition last month. The two-part IP for the 2012 Ford Escape/Kuga consists of a topper molded in Stamax 20% long-glass PP from SABIC Innovative Plastics, Pittsfield, Mass., and a retainer of talc-filled PP from Flint Hills Resources, Longview, Tex. Both use the MuCell process, licensed by Trexel Inc., Wilmington, Mass. (The company recently moved from Woburn, Mass.) The retainer material is reportedly the first PP compound in which talc was incorporated in the polymerization reactor, not in post-reactor compounding.
Microcellular molding saved 1 lb of material and 15% in cycle time (for a total of $3/vehicle) and allowed a 45% clamp-pressure reduction. The IP is molded at Faurecia in Louisville, Ky., on three 2500-ton presses (but only 1200 to 1500 tons of force are actually utilized). Challenges facing this project included the need to develop both design guidelines and a flow-simulation method for microcellular foam. What’s more, there was, initially, no sufficiently large press equipped for MuCell in North America. The first, used for the pre-production process development and tool debugging, was a 3000-ton machine at molder and moldmaker Proper Group in Warren, Mich. Ford is now working to develop Class A MuCell parts.