The Cleaning of Twin Screw Extruder
Posted by Andy
When do you need to clean your extruder?
- Some plastic will be carbonization after the extruder long time continues working. It will have some black spot inside the final granules.
- Some materials remain on the screw or barrel and gelled, and the material extrusion speed is slow.
- When you prepare to produce another kind of compounding plastic.
- When you need to change the color if you make the color masterbatch.
1. Use the resin to clean the extruder
Normally use the polyester resin or epoxy resin, like virgin PE, to clean the extruder. And meantime we can also add some lubrication additives and calcium carbonate.
Adopted a substance that has a certain friction and is easily crushed, like paddy, corn, sawdust, toilet paper, etc to clean the extruder. When the extruder heating to the extrusion temperature, then feeding this material into the extruder and using friction to clean the dirty between screw and barrel. According to our experience, the paddy has the best performance. And after this, normally we need to use the resin cleaning again.
3.Manual disassembly of screw and barrel cleaning
In this method, after the extruder is heated to the working temperature, the screw is pushed out by manual or automatic extrusion to remove the easily removed material. After cooling, it was immersed in an organic solvent tank containing acetone or cyclohexanone, and after the molten deposit attached to the screw was swollen, the attached matter was manually removed. The soaking time of the screw depends on the amount of the deposit and the thickness of the gel.
In order to use less solvent and facilitate the sealing of the container, a steel pipe or a stainless steel pipe which is slightly thicker than the screw diameter and a welded seal can be used as the soaking tank. For safety reasons, the container of the soaking screw must be stored in a cool place away from fire and power sources. At the same time, seal the mouth to prevent solvent evaporation and put a safety mark on it.
If it is necessary to thoroughly clean the machine, the barrel can also remove the glue attached to the inner wall of the barrel by manual method or solvent rubbing after the heat is turned on.
In order not to damage the surface finish of the screw and the barrel, it is not possible to hit with a hard object. Only use a steel saw blade or a copper brush that is softer than the screw and the screw to remove the attachment, so as not to damage the screw and the barrel. The standard for the amount of resin to be fed is to ensure that the powder coating material remaining inside the barrel can be completely pushed out of the barrel. From the degree of removal of the extruded material, the color of the original produced product or the absence of the paste is basically the standard.
When starting production with an extruder, the pre-mixed material is used to push out the material retained in the extruder according to a strict procedure. When it is confirmed that the material is cleaned, the extruded material can be used as a formal product.
1. If you need to stop the machine, you should keep the extruder barrel cooling system continue working to make sure the material cooling down fast to prevent material viscous aging in the extruder.
2. The feeder, screen exchanger, and die-head need to manual clean sometimes.
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