|How does the extrusion process work?
A picture of an extruder manufacturing line is shown above. (Move your mouse over the different parts of the image for descriptive names of each section.) First, raw material, in the form of small plastic pellets, is placed in the hopper. The hopper rests on top of the barrel. The barrel is a heated hollow steel cylinder, sort of like a really thick pipe. An auger-type screw rotates inside of the barrel. The screw's rotation takes the plastic pellets and pushes them forward, into the barrel. As the pellets move towards the front of the barrel, frictional and electrical heat from the barrel melt the plastic. After the plastic is melted, the rotating screw continues to act as a pump and forces the molten plastic through a die. The die is usually a piece of steel with the shape of the desired part machined into it. Once the melted plastic exits the die, it is shaped like the finished product. Next, it is pulled through some sort of cooling apparatus, which usually cools with air or water. Once cool, the product can be rolled up, cut into sections, packaged, or can go on to secondary operations.
Copyright ©1995 - 2002
Polymer Science Learning Center