Today, with advanced technology, cleaning plastic extruders is not a big problem, but how to properly and economically clean plastic extruders and keep the screw and barrel from being damaged is a problem. Today we will talk about how to properly clean the plastic extruder (mainly the screw and barrel).
How to clean the screw correctly
1. Select the correct heating device
It is the most common and effective method for plastic processing units to remove the plastic fixed on the screw by burning or baking, but it is absolutely not allowed to use acetylene flame to clean the screw. The temperature of acetylene flame can reach 3000 ℃. Using acetylene flame to clean the screw will not only destroy the metal properties of the screw, but also significantly affect the mechanical tolerance of the screw. If the acetylene flame turns to permanent blue when baking a certain part of the screw, it means that the metal structure of this part of the screw has changed, which will lead to the reduction of the wear resistance of this part, and even the peeling of the wear resistance layer from the base metal. In addition, local heating with acetylene flame will also cause overheating on one side of the screw, which will lead to screw bending.
The straightness of the screw is mostly within 0.01mm. When the screw is baked and cooled by acetylene flame, it is usually difficult to return to the original straightness. Correct and effective method: use a blowtorch to clean the screw immediately after use. Because the screw carries the heat during processing, the heat distribution of the screw is still uniform.
2. Select the correct detergent
Today, with the highly developed commodity economy, there are many kinds of screw detergent on the market, most of which are expensive and have different effects. Whether to use commercial detergent depends on different manufacturers and production conditions. Plastic processing enterprises can also use different resins to make screw detergrnt according to their own production conditions, which can save a lot of money for the unit.
3. select the correct cleaning method
The first step to clean the screw is to turn off the feeding plug, that is, to close the feeding port at the bottom of the hopper. Then reduce the screw speed to 15-25r/min, and maintain this speed until the melt flow at the front end of the die stops flowing. The temperature of all heating areas of the barrel shall be set at 200 ℃. Once the barrel reaches this temperature, start cleaning immediately.
According to the different extrusion processes (it may be necessary to remove the die head to reduce the danger of excessive pressure at the front of the extruder), so the cleaning must be completed by one person: the operator observes the screw speed and torque from the control panel, while observing the extrusion pressure to ensure that the system pressure is not too high. During the whole process, the screw speed should be kept within 20 r/min. In the application of low-pressure die, do not remove the die for cleaning first. When the extrudate is completely converted from processed resin to clean resin, immediately stop and remove the die head, and then restart the screw (within 10r/min) to make the residual clean resin flow out.
How to clean the barrel correctly
Cleaning the barrel is much easier than cleaning the screw, but it is also very important.
- When preparing to clean the barrel, the barrel temperature is also set at 200 ℃.
- Screw the round steel brush onto the drill pipe and the electric drill into a cleaning tool, and then wrap the steel brush with copper wire mesh.
- Before inserting the cleaning tool into the barrel, sprinkle some stearic acid into the barrel, or sprinkle stearic acid on the copper wire mesh of the cleaning tool;
- When the copper wire mesh enters the barrel, start the electric drill to rotate it, and at the same time manually make it move forward and backward until the forward and backward movement becomes no resistance;
- After the copper wire mesh is removed from the barrel, use a bunch of cotton cloth to wipe back and forth in the barrel to remove any cleaning resin or fatty acid residues; After several times of such back and forth wiping, the cleaning of the barrel is complete. The thoroughly cleaned screw and barrel can be assembled at any time for the next production!