Alphamid® film grades are supplied dry and ready-to-process. Material taken from original containers will have a moisture content <0.06%. During processing, the inner liner of (large) containers must be closed tightly. If the material is transported using pneumatic suction conveyors, the liner should be secured tightly around the suction pipe to limit moisture absorption from ambient air. Material from opened or damaged containers, as well as recycled waste such as edge trim, must be dried in a desiccant dryer at approximately 75 °C to 80 °C before processing. The recommended dew point is -30 °C to -40 °C. Experience has shown that a drying time of 8 to 10 hours will usually be sufficient to achieve an acceptable moisture level. Avoid drying temperatures above 80 °C because of possible oxidative damage (for example, yellowing). Possible defects from material containing too much moisture (>0.1%) include holes, bubbles, fluctuations in film thickness, foaming and hydrolytic degradation.

Standard single-flight, three-section screws.

Better results can be obtained by using high performance screws equipped with shearing and mixing sections,or barrier screws.

The screw length should be at least 24D, and preferably 28-33D to guarantee optimum plasticizing and conveying with the high through-put rates of film extrusion (Dscrew diameter).A three-section screw should have a compression ratio (ratio of flight depth in the feed section to flight depth in the metering section) of 3:1 to 4:1.

Screw length section (L: overall length of screw):

-Feed section: 0.25 to 0.30*L

-Compression section: 0.15 to 0.25*L

-Metering section: 0.40 to 0.55*L