From time to time it is necessary to do a complete audit on the condition of an extruder to make sure that it is operating in top condition for maximum effectiveness and efficiency. Following is some general information that should be considered to accomplish a good audit:
1. Evaluate the condition of the gearbox output shaft bearings with lift check.
a. Check and record the front quill I.D. for wear and proper fit with the shank of the screw.
b. Inspect and replace any shaft seals that may show leakage
c. Drain gear box lubricant and wash any residue and metal shavings in the bottom of the gearbox
d. Change lubricant oil filter
e. Check out gear box cooling system, primarily the heat exchanger if the extruder is fitted with one.
2. Check the front barrel support for proper thermal expansion, lubricate slide points with high temperature silicone grease.
3. Evaluate the effects of overhung loads which are produces for screenchangers, melt pumps and dies.
4. Measure and record the Feed Throat bore dimensions and inspect for excessive wear or water leakage from the cooling cavity of the cast housing.
5. Measure the barrel and screw for wear, envelope or complete profile.
6. Check extruder base to floor stability.
7. Evaluate heating and cooling system if required.
a. Flow test cooling tubes.
b. Use a clamp-type ammeter or a multi-meter test check the resistance of the heaters.
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; firstname.lastname@example.org; twwomer.com