K 2004 was notable for fans of polycarbonate car windows, who saw a multishot process that molds the glazing, then the frame, and provides exceptional optical clarity. Windows were molded on Battenfeld and Engel injection presses.
For Battenfeld GmbH, it was the second trade-show demonstration of its IMPmore technology, which uses the injection-compression process. The first time was at the 2003 NPE show in Chicago.
PC already is used in small glazing applications such as sunroofs and decorative side windows.
Although plastic front windshields still are a dream, machinery officials said at the Dusseldorf show that they think the technology is ready to break out into larger windows.
But it's a major challenge to mold a thin part with large dimensions that then is coated for resistance to scratching and ultraviolet light. ``You need less stress in the part, so you can coat it correctly,'' said Markus Kralicek, manager of applications engineering for large machines at Engel Holding GmbH.
Battenfeld used the low-pressure IMPmore process to make a large window, measuring almost 11 square feet. The injection-compression process has a mold that swivels slightly open when the cycle begins, then moves into normal position during molding. The mold was made by Summerer Technologies of Rimsting, Germany.
At K, the windows were removed by a six-axis articulating Kuka robot mounted on the two-platen HM press. The HM's tie bars telescope back when the mold opens.
The robot moved the windows to a quality-control station, where polarized light showed any molded-in stresses.
Battenfeld keeps pushing the envelope. The company showed an animation of a 1,430-ton HM press running at Battenfeld headquarters in Meinerzhagen, Germany. A new feature is direct sequential gating, which leaves no surface marks, said Joachim Berthold, manager of process engineering. It captures the frozen-off gate vestige at the end of the hot runner and keeps it from going into the mold on the next shot. The mold rotates and the frame is injected around the window.
Berthold said Battenfeld offers the revolving mold on presses that have 880, 1,430 and 2,970 tons of clamping force.
Engel, based in Schwertberg, Austria, molded a sunroof - with the frame molded around it - using its Glazemelt system on a 1,650-ton Duo two-platen press with a mold revolving between two injection units. The window and frame are both made of PC - clear for the window and black for the frame. In a touch of automated showmanship at K, the Kuka robot presented the sunroof to show-goers, lifted it high overhead, swung it around and placed it into a holding cart.
K 2004, held Oct. 20-27, marked Engel's first trade-show demonstration of automotive glazing production.
Kralicek said Glazemelt must inject from the side, because the gate cannot be on the window surface. That side injection, plus the demands of coining, put a premium on keeping the machine and mold parallelism under tight control.
Engel touted the fact that its window had a molded-in frame. ``This part is the biggest two-component part for glazing at the show,'' Kralicek said.