What is the recommended drawdown ratio for Eastman Provista™ copolymer?
• Normally a 2:1 is recommended when extruding Eastman Provista™ copolymer. This is necessary to achieve high production rates, while maintaining excellent clarity. • Running on an air table, one might get away with using a 1.5:1 drawdown when part wall thickness is greater than 2 mm (0.08 in.) but 2:1 is always preferable. • Keep in mind that when making a first cut on a new die being designed to run Provista™ copolymer, one should cut for an initial wall thickness drawdown that is half of the overall. For example, if cutting for an “overall” (everything but thickness) drawdown of 2:1, the wall thickness drawdown should be 1.5:1. So for a part with specs for a 2-mm (0.08-in.) wall for example, the die gap for a 1.5:1 drawdown should be 3 mm (0.12 in.). This “half the overall” approach will most often yield a wall thickness that is undersized. One would then follow the process described in this document for obtaining the correct thickness drawdown. The reason for having to follow this
