DUSSELDORF, GERMANY - Multicomponent injection molding got a new twist at K 2001, as several machine suppliers showed eye-catching presses with rotating molds that turn 90 or 180 degrees to meet up with separate injection units.
Equipment makers say the machines make many more parts than do presses equipped with conventional rotary tables. Also, offering the rotating-mold technology gives a machinery maker another opportunity to pick up a sale in the currently depressed market.
Ferromatik Milacron Europe positioned its offering, a K-Tec press fitted with a turning stack mold, right in front of its booth next to the aisle. Crowds watched the press, with 495 tons of clamping force, pop out 64 Colgate toothpaste-tube shoulder inserts at a time. German toolmaker Foboha GmbH made the mold, which had four sides, each with 64 cavities.
The mold faces turned between two injection units, one running PET, the other molding polyethylene. The second injection unit, placed at 90 degrees to the press to form a T shape, rests on rails, so it can be moved for different-size molds.
The red and white tube shoulders flooded out of the press, on a 10-second cycle. Parts were ejected while the mold was closed.
Ferromatik Milacron of Malterdingen, Germany, said the stack-turning technique results in double the production output for the same size of press.
All feed lines for cooling, heating, hydraulics, air supply and electronic monitoring are led centrally into the middle part of the mold via the upper and lower turning units. A hydromotor and gear mechanism drive the turning movement.
Over at the Engel Vertriebsgesellschaft mbH booth, a 990-ton Duo Combi-Cleanshot press was molding housings for automotive headlights, two at a time, on a 50-second cycle. On that press, the layout was two injection units set up in line, facing each other with the revolving mold in the middle.
The part includes a clear polycarbonate lens covering, molded to black PC edge seals.
Engel said the new Combi-Cleanshot concept can be achieved only with the two-platen Duo series, because the second injection unit is set up behind the mold-mounting platen. Power and resin are fed centrally from below the mold. Parts are removed from the side.
Engel was promoting the optical qualities of the lens covering, thanks to a special screw design. Also, there is no need for melt gating to the rotary central platen, because each component is served by its own injection unit. Schwertberg, Austria-based Engel said that makes it possible to mold large-surface components, such as headlight lenses or window glazing, using a two-component process.
Arburg GmbH + Co. of Lossburg, Germany, was molding a two-component, two-color cellular phone housing from PC and PC/ABS. An Arburg Multilift H robot removed the parts and set them down at the rear of the machine.
The second injection unit was positioned vertically, sending its shot down into the mold from above.
Having a variety of technologies, such as the rotating mold for multicomponent parts and horizontal and vertical clamping units, has helped Arburg win orders from processors that have specialized molding requirements, said Friedrich Kanz, president of Arburg Inc. in Newington, Conn.