Feature Article: Hybrid Injection Clamps The Best of Both Worlds? - 04/03
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Hybrid Injection Clamps The Best of Both Worlds?
In between all-electric and hydraulic-powered injection machines, a new species of hybrid clamp has emerged. Advocates say it combines the best qualities of electric servos and hydraulics without their disadvantages.
By Mikell Knights, Sr. Editor
Hybrid clamp designs that combine electric servomotors with novel hydraulic circuit configurations are now competing for molders’ attention as alternatives to all-electric or all-hydraulic clamping systems. A handful of OEMs supplying these new clamp styles say they can deliver greater processing speed and precision than conventional hydraulic-powered clamps at lower cost than all-electric machines.
Until recently, the term “hybrid” applied mainly to machines that used electric-driven screw plastication but hydraulics everywhere else. The case for that type of “hybrid” is that it provides most of the achievable energy savings at the smallest additional cost. Now there’s a new kind of hybrid in town, and its rationale is not mainly about energy savings.
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Van Dorn Demag Corp. Strongsville, Ohio (440) 876-8960 Demag Plastics Group, Krauss-Maffei, Meiki, Mitsubishi, and Sodick Plustech contend that their hybrid clamp configurations deliver the precision, accuracy, repeatability, and energy savings of servomotor designs along with the power, reduced initial cost, and familiarity of a hydraulic drive—but without the contamination and oil-maintenance issues. These suppliers say hybrid clamp systems, which achieve high-speed mold movements and fast tonnage generation, address issues they view as shortcomings of more traditional clamp styles such as hydraulic toggles, fully hydraulic, hydromechanical, and all-electric toggles. The cost of hybrid machines is in between those of hydraulic and all-electric models. Krauss-Maffei Corp. Florence, Ky. (859) 283-4310 Meiki America Corp. Elk Grove Village, Ill. (847) 439-4450 MHI Injection Molding Machinery Inc. Addison, Ill. (630) 693-4880 A new choice in injection machines is electric/hydraulic hybrids like this Eltec machine from Krauss-Maffei. Based on hydromechanical two-platen designs, they offer the speed and precision of electric servo drives plus the flexibility of hydraulic clamping. Nissei America Inc. Anaheim, Calif. (714) 693-3000 Yamazen Inc. Plastics Div. Schaumburg, Ill. (847) 882-8800 So far, few hybrid units have been sold in the U.S. Meiki leads the way with about a dozen sold here. Krauss-Maffei has around four hybrid machines at North American beta-test sites. Mitsubishi aims to sell 10-20 hybrid presses this year in North America, says Tom Geddes, general manager of engineering. The company has delivered more than 100 units to clients in Asia.
At present, U.S. molders decline to comment on their experience with hybrid clamps. “It is too early to say what improvements we are getting with the hybrid clamp,” says John Hahn, v.p. of engineering for molder MGS Mfg. Group of Germantown, Wis. The firm recently installed a new Eltec unit from Krauss-Maffei. The press may be used in a clean-room or optical application, Hahn says.