AMSTERDAM, NETHERLANDS — Polyurethane molders looking to do away with using preformed glass mats for reinforced parts now have a few more choices.
Two machine companies displayed competing coinjection solutions for structural reaction injection molding at the Polyure-thanes World Congress, held Sept. 29-Oct. 1 in Amsterdam.
Cannon SpA of Trezzano San Naviglio, Italy, introduced its InterWet PU mixing head at the congress, while Krauss-Maffei showed its LFI-PUR technology, first introduced at K'95 in Dusseldorf, Germany.
Cannon's new mixing head — which is based on an existing Cannon design — allows the introduction of reinforcing fibers or other fillers into the liquid mixing phase of the molding process, said spokesman Massimo Taverna.
The geometry of the mixing chamber allows thorough wetting of the reinforcing or filler material before it is introduced into a mold, Taverna said.
While Cannon's InterWet design is being marketed as an alternative to Krauss-Maffei's system, Taverna said his company's design has more uses.
``Our system allows the uses of materials from sawdust to cotton fibers to recycled polyurethane scrap,'' he said.
The system, he said, eliminates the need for preformed glass reinforcement mats in medium-depth molds, thereby eliminating a labor- and material-intensive process.
Meanwhile, Krauss-Maffei's dedicated fiber-reinforcement system is picking up steam among automotive suppliers, said Jim Jennings, the company's North Canton, Ohio-based regional sales manager.
LFI-PUR has been in development mode since its 1995 introduction, Jennings said. The system differs from Cannon's in that it is geared for use with glass or natural fibers, but not powder or granular fills.
The system also introduces chopped or continuous fiber strands just after the liquid PU components are run through the mixing head.
Current automotive applications for the process in Europe include door panels, parcel shelves and seat backs.
Europe was the first to start using the system, Jennings said.
``The U.S. is slow to start, and Asia hasn't started yet. But the U.S. carmakers have approved parts using the system. We just have to get the suppliers on board,'' he said.
Advantages of using the long-fiber injection method include material cost savings, he said.
``The material cost is 30 percent less when you buy [fiberglass] rovings as opposed to the mat,'' Jennings said.