Accuracy is the word for the all-electric MEtII Mitsubishi injection press from MHI Injection Molding Machinery Inc. (Booth S955).
The MEtII boasts an ultrarigid frame to suppress vibration and hold accuracy to a high level. The rigid clamping mechanism and double-roller supported movable die plates also make for an accurate machine.
To prevent an imbalance on the tie bars during mold opening and closing, two nozzle-touch ball screws connect the injection and clamping units.
The MEtII also incorporates a Super Resin Control II with other functions to ensure constant metering, as the screw applies pressure to the melt after metering. The process results in high repeatability of melt density and product weight on every cycle.
At NPE 2006, Mitsubishi is molding parts on a 390-ton MEII series Mitsubishi injection press, showing a mold temperature controller that heats and cools the mold very rapidly, to give a good part finish.
The MEII press comes in clamping forces of 390, 500 and 720 tons.
A beltless electric injection drive servomotor runs by direct drive linked to ball screws, coupled to a newly developed synchronous control, so the MEII instantly reaches maximum speeds.
The servomotor also reduces defects and cuts molding cycle times. MHI said dry cycle times have been reduced by 25 percent from the predecessor machine, the MI model. Platen deflection is 25 percent less, through the use of computer analysis.
MEII presses come with a MAC-VII controller.
In other news, MHI has taken its large-tonnage hybrid EM-series up a notch - with clamping forces of 3,300 tons and 3,900 tons. The machines combine electric and hydraulic features, drastically reducing cycle times. Mitsubishi said the big machines can mold a car bumper on a 30-second cycle.
High-speed mold opening and closing comes from the use of four direct-drive motors on the injection unit, which were specifically designed for injection molding presses. The motors are synchronized electronically.