Guide pins in a tool typically need a clearance of 2o micrometers and hence they don't contribute much if an application is ultra-precise as per Japanese toolmaker Nishiuchi Seisakusho (Kiryu).
The firm has produced what it calls the Floating Self-Centering Mold System that does away with guide pins altogether, while enabling the molding of precision components such as connectors with wall thickness down to 0.09 mm and core hole width of 0.12 mm.
Explaining the main idea behind the system at the recent IPF show, Nishiuchi Seisakusho CEO Kenji Nishiuchi presented a marker pen and repeatedly took off the cap and placed it back on. "Essentially, that's what's happening when the our tool opens and closes, and it does so with precision of 0.5 micrometers," he says. "The cavity half on the moving platen is attached via rigid springs and this enables it to mate perfectly with the half on the fixed platen during clamping," says Nishiuchi.
The tool was demonstrated at IPF on an Si-15 V BH150C all-electric injection press from Toyo Machinery & Metal Co. (Akashi, Japan) featuring linear guides for increased clamping accuracy and brushless moving die plate for increased cleanliness. The machine was molding 0.25-mm pitch connectors in a 4.8-second cycle time from LCP resin in a two-cavity floating self-centering tool. The machine boasts maximum injection speed of 700 mm/s and maximum injection pressure of 254.9.