Plastic extruder machines are used to manufacture a wide range of consumer, industrial and agricultural products. But, no matter what the end use, the basics of the different plastic extrusion machinery remain the same.
The Extrusion Process
All plastic extrusion equipment is made up of a hopper, a barrel and a die. To break the process down, plastic resin is first fed into the hopper. Depending on the application, the resin may have previously been mixed with additives like UV inhibitors or colorants.
From the hopper, the resin is fed into the barrel, where a screw moves the material down the barrel to the die. The screw not only moves the resin, but it also mixed the resin and heats the material up, allowing the resin to melt along the way.
Heating bands on the outside of the barrel help it reach the appropriate temperature for the specific resin being extruded. Temperatures can range between 400° and 530° F. The temperature rises progressively along the length of the barrel through three or more independent heater zones, allowing the resin to melt at an appropriate rate. The barrel temperature must be carefully monitored to prevent overheating, which can degrade the resin. In some instances, cooling devices may be used to reduce the temperature.
Before the melted resin reaches the die, it passes through a screen pack to remove any possible contaminants. The screens and a reinforcing breaker plate help create sufficient back pressure in the barrel to ensure the uniform melting and mixing of the resin.
After the resin passes through the die, the resulting shape is air or water cooled to reach its final temperature. The shape then can be rolled or cut to length.
Types of Plastic Extrusion Machinery
While they all work on the same premise, different types of plastic extruders are used for different processes.
Types of End Products
Plastic extrusion machinery is used to manufacture a wide range of products, such as:
Depending on the application, plastic extrusion machinery usually processes resins like polyethylene, polypropylene, acetal, acrylic, nylon, polystyrene, PVC, ABS and polycarbonate.