What Are the Cleaning Methods for the Screw?

The extruder screw can be cleaned by the normal replacement method or by using special detergent, the former method will consume a lot of resin.

1. Water cleaning of the extruder screw

Using a small amount of water to clean the extruder screw can reduce the cleaning time and avoid the appearance of crystal points during production. The specific steps are as follows (the following amount is set based on the typical extruder screw with a diameter of 90mm, L/D= 28).

(1) Set the extruder screw to rotate at a low speed of 10r/min.

(2) Add coating grade LDPE to the cleaned material.

(3) The extruder screw runs at a high speed for about 10min to allow LDPE to completely replace the original material.

(4) Insert a plastic tube into the raw material of the hopper, and slowly inject 100~200ml water into the extruder screw.

(5) After a few minutes, the foaming will start from the middle of the melt curtain before developing to full foaming.

(6) The melt will become clean again after the foaming process. After 15-20 minutes, you can reduce the speed of the extruder screw and add new material.

(7) Finish the operation and start production.

2. Variable speed flushing of the extruder screw

Another commonly used method to clean the extruder screw is variable speed flushing, which is also known as the disco flushing method. The steps are as follows:

(1) The extruder screw runs at a medium speed to remove the stored material.

(2) Change the flow sequence.

(3) If it is not cleaned with crystal spots and debris, you should continue the above steps until it becomes clear.

3. EVOH cleaning of the extruder screw

(1) Cleaning

You can use it directly without making other changes if it is switched from LDPE to EVOH. If it is switched from HDPE, PP, LLDPE to EVOH, you should first replace it with LDPE before using EVOH for extrusion. Especially after using PA and PVC, you should make sure to completely replace the resin in the barrel and die with LDPE before extruding with EVOH.

(2) Resin temperature

Please note that the temperature setting of the barrel and die as well as the control of the rotation speed of the extruder screw should not exceed 240℃.

(3) Detention time

It is based on 30 minutes. If the operation is interrupted for a long time, the extruder screw should rotate at a low speed to maintain the operation.

(4) Clean after the operation

If replaced with LDPE, it can be cleaned effectively in a short time.

(5) Notes for cleaning resin

Please do not use PP or HDPE when pre-cleaning or cleaning. There might be some problems if these resins contact with EVOH, and they will lead to difficult cleaning and caking.

Lesun is a screw barrel manufacturer which specializes in the production of parallel and co-rotating modular screw elements, extruder screws and barrels, covering Ø20mm to Ø300mm models. After ten years of vigorous development, we currently have many advanced CNC machine tools and special processing equipment for screw manufacturing. Besides, our machining operations have basically achieved intelligence and automation currently.

Our advanced processing methods, strong technical force, and sophisticated processing technology ensure that the quality and technical indicators of each production fully meet customer requirements. Welcome to consult.

  • What Are the Methods of Disassembly and Repair of Screws?

    What Are the Methods of Disassembly and Repair of Screws?

    June 8, 20211. Reasons for the damage of screw elements(1) The temperature of raw materials is low during plasticization.(2) The raw materials are mixed with metal foreign matters or the raw materials contain man...view
  • Disassembly Sequence of Extruder Screw and Barrel

    Disassembly Sequence of Extruder Screw and Barrel

    April 27, 2022When disassembling the extruder screw, special tools should be used and heavy hammer is not allowed. The specific disassembly steps are as follows:1. Disassemble the nozzle of the extruder screw and t...view
  • More Details about Screw

    More Details about Screw

    December 10, 2020Double screw generally divided into 5 sections: conveying section, melting section, mixing section, exhaust section, homogenization.1. Conveying section: conveying materials to prevent overflow.2. Mel...view
  • Three basic structural forms of extruder screw

    Three basic structural forms of extruder screw

    August 3, 2021According to the change of the screw lift and the depth of the screw groove, the screw of the conventional full-thread three-stage extruder can be divided into three types:Ⅰ. Isometric variable depth...view
top Inquiry