Netstal-Maschinen AG's Calitec cooling technology solves the problem of an extremely short cooling time for PET preforms — where the remaining heat inside the part can cause the preform to soften.
In conventional systems, the molded preform is guided into a cooling sleeve for post-cooling. As the preform shrinks away from the walls of the cooling sleeve and is no longer supported by the mold core, it loses contact with the sleeve around much of the circumference.
That means the cycle time is ruled by the post-cooling proc¬ess, Netstal said.
With Calitec, compressed air is pumped into the preform, giving a slight air pressure. This prevents the molded part from shrinking away. It is uniformly pressed onto the cooling sleeve, over its entire circumference.
A special device grips the preform and gently closes it off, then routes the low-level compressed air inside.
The calibration pressure slowly increases during the cooling phase, to counteract increasing shrinkage of the plastic.
Netstal is based in Näfels, Switzerland. The company's U.S. unit, Netstal Machinery Inc., is in Devens, Mass.
Tel. 978-772-5100, fax 978-772-5151, e-mail [email protected]