Views: 41 Author: Site Editor Publish Time: 2023-05-09 Origin: Site
When it comes to selecting plastic processing equipment, the screw barrel is one of the most important components. In the selection of screw barrels, nitrided screw barrel and bimetallic screw barrel are two common choices. Nitrided screw barrel is surface hardened to improve its wear resistance and longevity, while Bimetallic screw barrel is made of two different materials to take full advantage of their respective advantages.
Bimetallic Conical twin screw barrel
Although these two types of screw barrels have their unique advantages and are suitable for different application scenarios, they also have some differences and need to be selected according to specific requirements. This article will compare nitrided screw barrel and bimetallic screw barrel to help you better understand their differences, advantages and disadvantages.
Nitrided screw barrel is a surface-hardened screw barrel, which is processed under high temperature and ammonia gas environment to form a nitride layer on the surface, thereby improving its hardness and wear resistance. Nitrided screw barrel is mainly used to process common plastic raw materials, such as PE, PP, PS, ABS, etc. This treatment method is more economical and suitable for small and medium-sized injection molding machines.
Bimetallic screw barrel is a screw barrel composed of two parts, the outer layer is made of high-strength alloy steel, and the inner layer is made of high wear-resistant alloy. This structure can make full use of the advantages of different materials, and at the same time overcome the defects of a single material. Bimetallic screw barrel is usually used to process special or high-performance plastic raw materials, such as PA, PC, POM, PET, etc., as well as difficult-to-process materials such as glass fiber reinforced plastics.
Bimetallic injection screw barrel
The application scenarios of using nitrided screw barrel and bimetallic screw barrel depend on the materials and requirements of processing. Nitrided screw barrel is suitable for processing common plastics, such as home appliances, auto parts, office supplies, etc.
Bimetallic screw barrel is suitable for processing high-performance plastics, such as electronic components, optical equipment, medical equipment, etc. In addition, if different kinds of materials need to be processed at the same time, bimetallic screw barrel can also be used.
The difference in wear resistance between Nitrided screw barrel and bimetallic screw barrel is mainly in material selection and surface treatment. Nitrided screw barrel is made of nitriding treatment to enhance its surface hardness and wear resistance, while bimetallic screw barrel is made of two different materials, the outer layer is made of high-strength alloy steel, and the inner layer is made of high wear-resistant alloy into, thereby improving the overall wear resistance.
When measuring the wear resistance of the screw barrel, the common method is to test its service life or measure its wear degree. Among them, the service life test refers to the long-term use of the screw barrel under specific conditions to determine the duration of its continuous use. Another method is to evaluate the wear resistance of the screw barrel by measuring the wear degree. This usually involves measuring parameters such as the outside diameter, inside diameter and pitch of the barrel and comparing it to a new barrel to determine how worn it is.
Bimetallic Parallel Twin Screw Barrel
In addition, the wear resistance of the screw barrel can also be evaluated by observing the surface quality of the processed product. If the surface of the processed product is smooth without obvious scratches, it means that the screw barrel has better wear resistance. However, it should be noted that the surface quality of processed products will also be affected by other factors, such as molds, temperature and pressure, so it needs to be considered comprehensively.
In general, wear resistance is an important consideration when choosing between nitrided screw barrel and bimetallic screw barrel, and should be evaluated on a case-by-case basis.
Nitrided screw barrel improves its wear resistance and corrosion resistance by nitriding the surface of the screw barrel. Nitriding treatment can form a surface layer with high hardness, good wear resistance and corrosion resistance. This surface layer can protect the internal metal structure of the screw barrel from corrosion and prolong its service life. However, if the nitriding is not uniform or the thickness is insufficient, it will lead to a decrease in corrosion performance.
Bimetallic screw barrels are made by welding high corrosion-resistant alloy materials (such as 316L stainless steel) to the surface of raw materials to form a composite layer to improve the corrosion resistance of the screw barrels. The advantage of this screw barrel is that it has better corrosion resistance, especially for corrosive media such as strong acid and strong alkali, and has better resistance. However, due to the stress difference between the coating and the substrate, problems such as coating peeling are prone to occur.
Corrosion conditions are also different in different environments. For general corrosive environments, such as general plastic processing, food packaging and other industries, Nitrided screw barrels can meet the needs, while Bimetallic screw barrels are more suitable for use in highly corrosive environments such as strong acids and alkalis. In addition, under the environment of high temperature and high pressure, the corrosion resistance of Bimetallic screw barrel is also more prominent.
In long-term use, the overall economic benefits of nitrided screw barrel and bimetallic screw barrel also have their own advantages and disadvantages.
Nitrided screw barrel is relatively cheap because it improves its wear resistance and corrosion resistance through nitriding treatment, and is suitable for some plastic processing enterprises in low-corrosion environments. In addition, the maintenance cost of the nitrided screw barrel is relatively low, and compared with the ordinary screw barrel, the service life is longer. However, the nitrided screw barrel also has a disadvantage, that is, the thickness of the nitrided layer is limited, which cannot meet the requirements of some highly corrosive environments.
Bimetallic screw barrels are better used in highly corrosive environments due to the use of high-corrosion-resistant alloy materials. Although the price is relatively high, its maintenance cost is relatively low and its durability is stronger in long-term use. However, due to the stress difference in the welding process, problems such as coating peeling may occur, and more professional maintenance is required, and the maintenance cost is relatively high.
Therefore, it is suggested that when choosing a screw barrel, it should be selected according to the production environment of its own enterprise. If it is a plastic processing enterprise in a low-corrosion environment, you can choose a nitrided screw barrel; if it is an enterprise in a high-corrosion environment (such as chemical industry, medicine, etc.), you should choose a bimetallic screw barrel. At the same time, during use, attention should also be paid to the maintenance of the screw barrel to avoid affecting its durability and economic benefits due to long-term use.
Parallel Twin Screw Barrel 
Conical Twin Screw Barrel 
