Film on Chill Rollers - 995R Claw

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Problem

Cast plastic film exits from the die in a semi molten (and hot) state directly on to a chill roller. As the plastic cools on the roller, it shrinks in width – Known as ‘Necking’. This is undesirable as it makes the finished film uneven and prevents the full width of the extruder from being used.

Previously compressed air jets have been used to hold the edges of the plastic at the desired width. This is costly, noisy and can leave excessive marking on the film.

Solution

A better system is to pin the edges using static electricity. The Meech 995-CLAW is specifically designed for this purpose. One pinning head is mounted either side of the film. The 25mm diameter mounting rod allows the use of standard industrial clamps and provides lateral and rotational adjustment. Three flexible titanium points can be positioned in an array to suit the application. Each point is individually resistively coupled to provide powerful independent pinning without the risk of sparks damaging the very expensive roller.

The use of extended pins allows the operator more space to work when he is setting up the film at the start of a run. Typically, a compressed air gun is used to push the film out to the desired width, at which point the pinning head pins is switched on and the film is held in place. An ideal installation will have a dedicated static generator for either side of the roller, to allow the two edges to be manipulated and pinned independently. Meech recommend that the 995-CLAW is used with a 30KV 992v3 negative generator. The built in remote on/off control simplifies operation of the high voltage output; allowing the generator to be switched on by a simple switch mounted near the pinning head.