Screw and barrel are the most critical and soul parts of injection molding machine, which is often called the heart of extruder. Plastic (rubber) formally in this part from glass to viscous flow, and then through the mouth mold, auxiliary machine and made into a variety of products. From the analysis of extrusion process, we can see that at least the screw should be evaluated from the following aspects.
First, output
Yield refers to the output or extrusion volume of a given head under the premise of ensuring plasticizing quality.
Second, chemical, mechanical, or batch number, reduce energy consumption, reduce the burden of the main and auxiliary cooling system. That is, polyethylene and polypropylene are different from polyolefin.
Third, unit consumption
Unit consumption refers to the amount of energy consumed per kilogram of plastic (rubber) extruded, the head resistance and screw performance of the match is more important, not good, the quality of the product is also different. For example, low temperature extrusion is a development trend, it can improve the quality of extruded products (such as reducing internal stress, etc.), preheating and non-preheating also have an impact on processing performance, radial temperature difference.
Fourth: adaptability
The adaptability of screw refers to the adaptability of screw to processing different plastics, matching different heads and different products. Formerly, amorphous plastics. Even the same is polyethylene. Therefore, different screw designs should be adopted to adapt to different materials without obvious melting point and electrical properties.
Fifth: the difficulty of making
A good screw must also be easy to process and low in cost.
Sixth: feeding section
The groove is deep and fixed, and its function is to preheat and plastic solid conveying and pushing. Plastics must be guaranteed to start melting at the end of the feed section.
