In recent years, injection molded polycarbonate car windows have made regular appearances at major trade shows, and NPE 2006 continued the trend.
Milacron Inc. and Engel Machinery Inc. demonstrated the process in their booths. Japanese press maker Meiki Co. Ltd. announced a project together with PC resin supplier Teijin Chemicals Ltd.
Milacron ran a PC side-panel window for a sport utility vehicle, on a two-platen Maxima MG machine with 1,100 tons of clamping force. A second injection unit overmolded the window with a black-PC frame.
The Milacron press uses the coining process to avoid the molded-in stresses that can damage the clear, optical quality needed in a car window. Also called injection-compression molding, coining keeps the mold slightly open as it fills, then applies full tonnage to compress the material inside the mold.
After the side windows came out of the press at NPE 2006, a robot moved each one to an Avalon vision inspection station, where infrared light showed any molded-in stress. Another feature was a Staubli magnetic mold-clamping system for quick-mold changes.
Milacron mounts the second injection unit on an injection sled above the main injection unit. The sled is mounted to the stationary platen.
Milacron is based in Cincinnati.
At Engel's booth, a 1,650-ton, two-platen Duo Combi M turned out two-color automotive sunroof panels. Engel of Guelph, Ontario, mounted the second injection unit behind the moving platen.
A six-axis Kuka robot removed the sunroof parts.
PC automotive glazing at a trade show certainly grabs the attention of attendees. Officials of Milacron and Engel said it also demonstrates a basic reality - multishot molding of large automotive parts.
Both companies are marketing their big presses to mold things like instrument panels and door panels, which can be overmolded with a soft skin material such as a thermoplastic elastomer.
Meiki did not show a press running car windows at the NPE booth of its U.S. unit, Meiki America Corp. of Elk Grove Village, Ill. Instead, officials of Meiki and Teijin Chemicals announced that a 3,740-ton Meiki press started running windows, just before NPE, at Teijin's technical center in Chiba, Japan.
The two companies launched the $1.8 million project in March. The press, a Meiki MPIP-2100-HR2, is a two-component, rotary press that does injection compression molding.
The ultimate goal: to position Meiki and Teijin as a leader in two-component molding of really large glazing parts.
The press is big enough to mold parts measuring up to 4 feet by 5½ feet.
Meiki America Toshimichi Ito said polycarbonate windows are still pretty rare in Japan and the United States. But European automakers are way ahead, already selling cars with two-component PC rear quarter windows and sunroofs.
The trend, again starting in Europe, is toward plastic windows with a much larger surface area, according to Toshiaki Hotaka, leader of the polymer processing group at Tiejin's technical center. Examples are a panoramic PC roof, which covers most of the roof of a car.
Eventually, Meiki and Teijin hope to be the first to mold ultra-large-scale parts that integrate glazing and automotive body panels.
NPE 2006 attendees didn't have to travel to Europe to see radical roof glazing on a car. Bayer MaterialScience LLC drew crowds to see its concept car, the zaZen, which sported an entire roof dome made of Bayer's Makrolon PC.
NPE was held June 19-23 in Chicago.