In the extrusion production process of plastic particles, in order to improve the performance of the product, various chemical additives are often added, but this is more likely to cause wear and corrosion of the twin screw extruder screw and barrel, which will cause a large number of the resources waste and also affect the quality of plastic products, and even directly cause the machine to fail work.
In order to improve the wear resistance of the extruder barrel, at present, the wear-resisting treatment methods of the extruder barrel are summarized and analyzed.
The wear-resistant treatment of the extruder barrel is divided into the following two steps:
1. Nitriding
Nitriding treatment technology is currently mainly divided into three categories, one is ion nitriding, the second is gas nitriding, and the third is liquid nitriding. Among them, the best effect is ion nitriding. Gas nitriding and ion nitriding are carried out on the screw, and the service life can reach 2 to 3 times.
2. Chromium and molybdenum plating
Chrome and molybdenum plating treatments also play a significant role in improving the wear resistance of the twin screw extruder barrel. At present, there are many specific process methods of chrome plating technology, such as black chrome plating, milky white chrome plating, hard chrome plating and decorative chrome plating. The functional effects they can achieve vary. In the wear-resistant treatment of the twin screw extruder screw and barrel, hard chrome plating is mainly used to improve the hardness of the barrel, thereby enhancing its wear resistance.
In the actual treatment process, the material of the barrel is preferably 45# steel or 40Cr steel, and the thickness of the chromium layer should be at least 0.05mm, but not more than 0.2mm. After treatment, the inner surface of the barrel can maintain good cleanliness, the corrosion resistance and wear resistance will be greatly improved, and the chemical stability is good. In addition to chrome plating, the surface sprayed molybdenum layer can also significantly improve the corrosion resistance and wear resistance of the barrel, and effectively reduce the wear caused by various reasons in the production process. Its main process is divided into three steps, one is nitriding steel screw material, the second is nitriding treatment, and the third is plasma spraying.
There are integral liner and C-type liner, as shown in the photo:
In addition to the above two methods, the most important thing is our standardized operation of the machine. During the injecting material process, other substances such as sieve residues, iron filings, etc. cannot be allowed to enter the extruder. Before starting the machine, you must control the temperature and time indicators according to the relevant operating requirements. It is not possible to reduce the heating temperature index and time for the convenience of production.
In addition, during the start-up process, the hopper should be checked to determine whether there is any material in it, and it cannot be run without load, nor can it run at low temperature, high temperature, high pressure or high extrusion speed.
Equipped with a standby generator to ensure that the material can be extruded in time in the event of a power failure, and then shut down in a normal state. In the case of not equipped with a standby generator, the screw and barrel should be thoroughly cleaned with cleaning materials after the power is heated up.
It is best to run the machine continuously for a week, minimize frequent start/stop, and do daily inspection and maintenance work to ensure that the machine is always in good operating condition. In the case of needing to stop for a long time, the screw and barrel should be cleaned with cleaning material, sealed with silicone oil, and the hopper should be covered and sealed with plastic cloth.
Standardized operation is the best solution for efficient production.
