FREQUENTLY ASKED QUESTIONS (FAQs)
Q: What are barrels?
A: The barrel of an extruder is a hollow chamber in which the feed-screw (or screws) operates. If one screw is used the barrel has a cylindrical cross-section: if two screws are used, the barrel has a figure eight (8) cross section. It is the screw and the barrel, which interact to melt, convey, and generate pressure on a polymeric material within an extruder.
Q: What are feed screws?
A: Feed-screws, when used in the plastics industry, are the critical component in manufacturing polymers. The feed screw turns within a cylinder (aka a barrel) in the extrusion or injection molding process, to provide a uniform material flow. Feed screws in combination with a variable flight pitch and flight length as well as the addition of a mixer can be used to provide uniform flow and dispersive and/or distributive mixing for a variety of polymers. As the feed screw turns, the processed polymer is extruded or injected into a die or mold.
Q: Why is my feed screw really worn out in the feed section?
A: Too much material is being under processed and over compressed in this area, which cause premature wear.
Q: When does a barrel need to be replaced?
A: If the press is running at optimum efficiency, and there are no issues, the barrel will typically need to be replaced after three (3) screws have been worn and replaced. At this point, the barrel has reached the end of its useable lifecycle.
Q: Why is a free flow valve recommended?
A: It helps reduce residence time for the material, which reduces the opportunity for material to burn.