Today, when technology is developed, cleaning plastic extruders is not a big problem. But how to properly and effectively clean the plastic extruder and keep the screw and barrel from damage can cause a lot of trouble if it is improperly operated. Today, JWELL teaches you how to properly clean a plastic extruder.
01How to properly clean the screw of the plastic extruder
1) Select the correct heating device
Using fire or roasting to remove the plastic stuck to the screw is the most common and most effective method for plastic processing units, but acetylene flame should never be used to clean the screw. The temperature of the acetylene flame can reach 3000°C. Cleaning the screw with acetylene flame will not only destroy the metal characteristics of the screw, but also significantly affect the mechanical tolerance of the screw.
If the acetylene flame turns persistent blue when baking a part of the screw, it means that the metal structure of that part of the screw has changed, which will reduce the wear resistance of the part, and even peel off the anti-wear layer from the base metal.
In addition, local heating with acetylene flame can also cause one side of the screw to overheat, which causes the screw to bend. Most screws are made of 4140.H.T. Steel, and the tolerances are very tight, generally within 0.03mm.
The flatness of plastic extruder screws is mostly within 0.01mm. When the screw is baked and cooled by acetylene flame, it is often difficult to return to the original flatness. Correct and effective method: Use a blowtorch to clean the screw immediately after use. Because the screw carries heat from the processing process at this time, the heat distribution of the screw is still uniform.
2) Choose the right cleaning agent
Today, when the commodity economy is highly developed, there is no shortage of screw cleaners (screw cleaners) on the market. Most of them are expensive and have different use effects. Whether to use commercialized cleaners depends on different manufacturers and production conditions; plastic processing enterprises can also use different resins to make screw cleaners according to their own production conditions, which can save a lot of money per unit.
3) Choose the right cleaning method
The first step in cleaning the screw is to turn off the feed plate, that is, close the discharge 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 zones of the barrel should be set at 200°C. As soon as the barrel reaches this temperature, start cleaning.
Depending on the extrusion process of the plastic extruder (the die may need to be removed to reduce the risk of excessive pressure at the front end of the extruder), cleaning must be done 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 is not too high.
The screw speed should be kept within 20r/min during the whole process. In the application of low pressure die, do not remove the die for cleaning first. Immediately stop the machine and remove the die when the extrusion is completely converted from the processing resin to the cleaning resin, and then restart the screw (speed within 10r/min) so that the residual cleaning resin can flow out.
02How to properly clean the barrel of the plastic extruder
Cleaning the barrel is much easier than cleaning the screws, but it is also very important.
- When preparing to wash the barrel, the barrel temperature is also set at 200°C.
- Screw the round steel brush to the drill rod and electric drill into a cleaning tool, and then wrap the steel brush with a 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 artificially move it back and forth until this back and forth movement becomes unresistive;
5.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 residue; after several such wipes back and forth, the cleaning of the barrel is completed. Thoroughly cleaned plastic extruder screws and barrels are ready to be assembled for the next production.