How To Clean The Injection Molding Screw Barrel


    Cleaning the screw and barrel may require a full day's work, even by two or more operators. This can be done by disassembling parts or injecting purification compounds. It is not always necessary to remove the Injection Molding Screw Barrel and barrel from the machine, but it may be more cost-effective than using a cleaning agent. The following content will guide you to use any cleaning method.

    Use cleaning agent
    When using a purge compound, the first step you need to take is to close the resin flow being processed by pushing the sliding door at the bottom of the resin hopper to close. Next, slow down the rotation speed of the screw by approximately 15 to 25 rpm until the polymer stops flowing from the end of the mold and/or the nozzle of the machine. The temperature of the barrel area of ​​the molding machine should be around 200º C (400º F) to start the cleaning process. Split-melt high-density polyethylene (HDPE) is used as a purification compound. The size of the screw determines the amount of HDPE needed for cleaning without overloading.

    For team operations, the second operator should observe the head pressure gauge to ensure that the system is not overpressured, and monitor the screw to ensure that it always rotates at 15-20 rpm. If the mold remains on the extruder, continue the cleaning process until you notice a complete change in the extrudate from processing resin to cleaning resin.

    Once the mold is completely cleaned, the rotation of the screw can be completely stopped, so that the mold or end cap on the extruder can be removed, exposing the end of the screw. The screw can then be restarted and rotated to 10 rpm to pump out the remaining HDPE cleaning resin from the rest of the screw.

    Remove the screws and barrel
    After pulling the remaining HDPE out of the screws, you will need to remove the screws. After removing the rotary joint, hose and pipe from the rear of the extruder, you can connect the screw extractor unit to the extruder gearbox. Then, the screw can be pressed down to most of the barrel by the screw extractor. After that, you need to push the screw out about 4-5 turns to expose it for cleaning. You can use a copper wire brush and copper putty knife to scrape off the excess HDPE on the screws. Repeat the process of rotating the screw outwards and removing the HDPE until the entire screw is exposed and all large amounts of HDPE are removed. To remove the HDPE residue after this, you can sprinkle stearic acid on the root of the hot screw and scrub it with brass gauze, which will also polish it. Finally, wipe with a cotton cloth to complete the cleaning process of the screws.

    When cleaning the barrel, coat the inner bore of the plasticized barrel with stearic acid, and wrap the copper gauze (or stearic acid) with a round wire brush and push it into the inner bore. Use an electric drill to rotate the brush until it can easily get in and out of the barrel hole. You may need to add more stearic acid before it is finished. After completing this step, a bundle of cotton cloth can be used to wipe the length of the inside of the barrel hole and remove the HDPE or stearic acid residue. Once you wipe the barrel hole clean with a bundle of rags, the process is complete.

    In fact, the cleaning process of any type of screw is similar, even the Single Screw Extruder Screw Barrel is no exception. If you need to clean the screw, you can also refer to the above content.