Unless you work with plastic extruders every day, you probably are not going to be very familiar with most of the technology or the jargon. Therefore, when you hear the phrase, "cooling screws," you may find yourself at quite a loss as to what these objects are and how they relate to plastics extrusion. You may be even more confused when someone talks about keeping these screws from overheating and failing. Here is a more precise and understandable definition for cooling screws, what they do and how to keep them from failing, should you ever find yourself in a plastics extrusion job.
What Cooling Screws Are
Cooling screws are large, elongated, screw-shaped components found in a plastics extrusion machine. They are inserted horizontally along the bottom of this machine and are meant to turn and cool the melted plastic before it is pushed into a mold. They are often metal, but they may be a heat-resistant type of material other than metal as well.
What They Do
The cooling screws reduce the friction of the plastic melt as it is moved from one part of the extruder to the next. It continues to grind fine particles of plastic that have caught onto the screw, thereby recycling even the smallest bits of material. It churns melted plastic in the same way that a concrete mixer continues to mix and churn concrete. Finally, it helps cool the hot plastic melt just enough for the extruder to force the melted plastic into molds, where it cools, re-solidifies and conforms to the shapes into which it was extruded.
How to Keep Them from Overheating and Failing
Oddly enough, these screws can overheat, even though their primary function is to cool melted plastic. When they overheat, they begin to fail and will not properly turn or process the melted plastic, which means the machine gets jammed up and the melted plastic will be useless if the cooling screw cannot be fixed promptly. Cooling the screws with a lot of water is generally the approach taken, with the best approach being cooled water from a nearby tower. For this reason, many plants may have their own water towers close by, as well as a means to refrigerate this water for use in the extruders. In the event that you have the start of an overheating cooling screw, and the cooling tower water does not seem to be getting to the cooling screw, have a backup water cooling source. Contact a manufacturer, like AUSTIN MAC INC, for more help.