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Timothy Womer Founder
Tim Womer is a recognized authority in plastics processing and machinery with a career spanning more than 35 years. He has designed thousands of screws for all types of single-screw plasticating. He now runs his own consulting company, TWWomer & Associates LLC. Contact: (724) 355-3311; tim@twwomer.com; twwomer.com
Troubleshooting Screw and Barrel Wear in Extrusion
Extruder screws and barrels will wear over time. If you are seeing a reduction in specific rate and higher discharge temperatures, wear is the likely culprit.
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Try a ‘Complete’ Method to Clean Screws, Barrels
Pulling the screw will give you direct access to clean all surfaces. Here’s how to do so in an efficient, safe, and non-destructive way.
Read MoreCalibrate Those Instruments
Make sure that your instruments are calibrated on a regular bases and also do a check and balance when gathering data. Never trust what you think you see the first time.
Read MoreEnsuring A Consistent Polymer Feed
If the feedstock is not introduced to the feedsection of screw in a smooth and uniform matter, then the likelihood of a stable and consistent output is low.
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Internal Screw Cooling
This simple cooling system gives the operator another temperature cooling zone on the screw that can be used to improve feeding.
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Screw Cooling
In most cases, screw cooling will benefit the process by giving the operator another “zone” of control on the extruder. The main theory of “solids conveying” is that the resin must “stick to the barrel” and “slip on the screw.” By cooling the root of the screw, it will reduce the coefficient of friction between the steel of the screw and the plastic pellet. By cooling the root of the screw, it will reduce the coefficient of friction between the steel of the screw and the plastic pellet.
Read MoreOversizing Screws and Barrels
It might sound like an economical approach to rebuilding, but you could see a big drop in quality if you go this route.
Read MoreBuying Used? Be Careful
An old extruder is unlikely to have the same capabilities--especially in the area of torque--than a new one will have.
Read MoreStainless Steel Screws
For smaller screws up to 2.5 in. diameter, and for PVC processing applications, you might find this to be the best choice.
Read MoreHow To Stop ‘Windmilling’
Many times I hear molders complain that their screw is “windmilling” or not picking up the material.
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