Extrusion Screws 

Feed Section

Lengths should be to a minimum, based on projected shot size. Excessive length is wasted processing space. Front or push side flight radius very small for proper feeding, back or trailing side radius should be larger to increase strength and can be used to control input volume. 

Transition Section

Very long compression length impart the shear or drive energy more uniformly, allow more electrical energy into the process and increase the length and effect of any back pressure applied. 

Meter Mix Section

Shorter length can be adequate when using a type of distributive mixer to interrupt the problems associated with lamina flow, in the screw, nozzle body and hot runner systems. 

Compression Ratios

Much higher compressions that range from 3.2 – 3.8:1 can be used, the shear impact is more that overcome with a long transition length. The required compression should be lower for longer L/D screws and higher for lower L/D Screws. 

The Plastics Directory is always adding new listings and updated information on new and existing products. Keep checking back for the newest technology in the Plastics Market.