top of page

Supplier Tips

How To Clean Screws & Barrels from

reiloyusa-logo.png

1.

2.

The right cleaning tools are a brass putty knife, brass wire brush, copper gauze, and stearic acid flakes. Avoid allowing plastic to harden requiring an acetylene torch and steel wirebrushes to clean a screw.

gauze.jpg
brush.jpg
scraper.jpg

First purge the barrel empty. Once the screw is exposed, remove resin from the screw using brass tools and a brass wire brush, never steel. Steel will damage screw and barrel surfaces.

3.

After removing most of the molten resin, polish the screw with copper gauze and then a soft rag

screws.jpg

USE THE RIGHT TOOLS
Using acetylene torches, steel screw drivers, scrapers or pry bars to remove plastic can cause costly or irreparable damage to a screw and barrel. Tools and supplies for cleaning a screw and barrel are few and simple: high-heat gloves, safety glasses, a brass putty knife, brass wire brush, copper gauze, stearic acid flakes, an electric drill, cotton rags, and a round brass wire brush (about the ID of the barrel) mounted on a rod. Negative effects of acetylene torch use:

  • Softens steel at point of focused flame; can alter metallurgical properties and reduce hardness

  • Increases likelihood screw will break under torque load

  • Possible delamination of welded flights from base metal of the screw

  • Metal expands unevenly on the side where heat is applied causing warping

  • Secondary plating, like chrome, can soften, crack, flake and peel

A less destructive and efficient alternative to blow torching is to purge and clean the screw
immediately after use while it is still evenly heated from production.

Make sure the barrel is purged empty. We suggest keeping the barrel hot enough so the plastic remains pliable. Safety is number one so be certain heater bands that must be removed are disconnected and locked/tagged out. Follow the machine manufacturer’s instructions for disassembly and push the screw forward (out of the discharge end) until a flight or two is exposed. If equipped, remove the non-return valve from the screw, clean and set aside. Using brass putty knives and scrappers clean off the majority of the molten resin from between the screw flights. Repeat this
process three to five flights at a time until all surfaces have been cleaned and most of the purge resin
removed.

Once the large amounts of purge have been removed with the brass putty knife and wire brush,
sprinkle stearic acid flakes onto the root of the hot screw (stearic acid can be purchased from a resin
distributor). Use copper gauze to remove any remaining residue. After the entire screw has been
polished with copper gauze, do a final clean-up using a soft cotton rag. This will ensure that there is
no contamination in the next production run.

Once the screw is completely cleaned, it can be set aside until the barrel has been cleaned, or placed
on a screw rack until the next time it's needed. If the screw is stored, it should be sprayed and wiped
down with light oil, such as WD-40, to prevent rusting. Chrome-plated screws are less likely to rust
during storage and don't require oiling.

cleanBarrel.jpg

Cleaning the barrel is much easier than cleaning the screw but just as important. With barrel temperatures still set at 400 F, the barrel is ready to clean. First, assemble the round wire brush, extension rod, and electric drill to make your cleaning tool. Then wrap the wire brush with copper gauze.

Before inserting the brush and gauze assembly into the bore of the barrel, throw in a handful of
stearic acid. You can also sprinkle stearic acid over the copper gauze before pushing the
brush/gauze assembly into the barrel. Once the brush/gauze assembly is inside the barrel, use the
electric drill to rotate it while moving it in and out until it moves easily. You may need to use additional
stearic acid before the bore is thoroughly cleaned.


When the brush/gauze assembly is removed from the barrel, push a bundle of cotton rags back and
forth inside the length of the barrel to remove any purge or stearic acid residue. When the rags have
been passed back and forth several times and return totally clean, barrel cleaning is complete. The
entire screw and barrel assembly are nearly and spotless and ready for the next production run.

logo-color.png

WEST MICHIGAN SALES

Joe Fulsher

810-523-2343
joe@waksite.com

P.O. Box 267 Lowell., MI 49331

EAST MICHIGAN SALES
Steven Taugher
248-376-3416
steven@waksite.com

P.O. Box 380115 Clinton Twp., MI 48038

© 2024 by WAK Plastics Machinery

bottom of page