CHICAGO (Aug. 1, 4:15 p.m. EDT) — NPE 2006 was a direct-drive show for Sumitomo Plastics Machinery America LLC, as five of its six show machines sported direct-drive technology, with no drive belts.
Direct-drive motors have a faster response time than traditional all-electrics that use a belt to drive the ball screw, according to Jeff Hicks, vice president of technical sales.
``Because of the lower inertia, it can respond to signals faster, accelerate and decelerate faster,´´ Hicks said. ``You don´t have to turn two pulleys or turn a belt. It can get up to speed faster and decelerate, to hold the shot size.´´
In Japan, Sumitomo designs and builds its own electric motors, which gives it an advantage, Hicks said. For example, Sumitomo engineers moved the ball screw forward, in front of the motor, in order to expand direct drive to larger-tonnage injection presses. Initially, the physical size of the area on the machine holding the direct-drive motor was very large because the ball screw was located inside the motor.
Sumitomo also used NPE 2006 to introduce the patent-pending Double Center press platen, shaped to turn the force more toward the center of the platen and improve the distribution of clamping force. Sumitomo claims the platen design can eliminate problems of short shots and flash, while improving mold protection. The design also can reduce the clamping force required to mold a part by as much as 20 percent, the firm said.
Also at NPE 2006, held June 19-23 in Chicago, Sumitomo demonstrated micromolding on two all-electric presses.
The new SE7M Micro press, a direct-drive machine with 8 tons of clamping force, is Sumitomo´s smallest-ever direct-drive model. The line used to stop at 18 tons on the small side.
The Micro turned out teeny, narrow-pitch connectors every 3.3 seconds, on a four-cavity mold with hot runners. Part weight: 0.001 ounce.
A control option, the SK-II, gives very precise injection fill, including shot weight and density, and stability of the peak pressure. The press can run on injection speeds up to 300 millimeters per second.
The other micromolding press was a 20-ton SE18DU, a larger machine that molded much smaller parts - a bobbin used in miniature electrical devices. Makuta Technics Inc., a micromolder in Columbus, Ind., molds the part, which weights just 0.00001 ounce. The press molded the parts on a two-cavity mold, running a 4.8-second cycle.
Sumitomo has a patent pending on a new feature, a constant feedback force-correcting system that uses a strain gauge on the tie bar, which measures actual clamp tonnage even when it changes because of thermal expansion of the mold.
Larger SE-DU direct-drive machines also were at work, molding medical syringes on an 83-ton press and pipettes on a 143-tonner.
Another new press, the midsize all-electric SE-HS line, uses direct drive to run both injection and clamping on presses ranging in clamping force from 242-398 tons. Sumitomo said the press is suited for parts that have a cycle time less than 15 seconds, thin-wall parts and packaging, among other applications.
In Chicago, a 242-ton press was running medical specimen containers.
Patent-pending features on the SE-HS include the strain gauge on the tie bar, plus the SM screw with low shear, thorough mixing at low temperatures and shorter cooling times.
Also new at NPE 2006 was Sumitomo´s midsize SE-HD, an all-electric with a belt drive. This machine line is designed for thicker-wall parts with more than 15-second cycle times, because it can maintain very high pack-and-hold pressure for an extended period of time.
The SE-HD also sports the Double Center press platen and the clamping force feedback.
At the show, the machine was molding automotive taillight covers in a two-cavity mold every 35 seconds.
Sumitomo Plastics Machinery also rolled out its iii-System production and quality monitoring system at NPE.
The company provided real-time monitoring of all six presses in the booth.
Sumitomo Plastics Machinery is based in Norcross, Ga.
