In the PVC extrusion industry, screw breakage is a common issue that severely impacts production efficiency and product quality. Screw breakage is typically categorized into normal wear breakage and abnormal breakage. Below is an analysis of the causes of these two types of breakage and preventive measures: 1.Screw Processing and Materials **Material Selection** – Barrel Material: Commonly used materials include Cr12MoV (SKD61 alloy steel) and 38CrMoAlA. – Screw Material: 38CrMoAlA is typically chosen. **Heat Treatment Process** – Barrel: Tempering is used to homogenize the internal structure and improve the metallurgical grade. Two-stage alloy steel parts undergo overall quenching, achieving a hardness of HRC60 after quenching. – Screw: The final heat treatment is surface nitriding, with a nitriding depth of 0.5-0.7 mm. Large companies can achieve a nitriding depth of over 0.6 mm. **Bimetal Processing Methods** Metal processing methods generally include forging (for large parts) and casting (for small parts). **Service Life** The service life of the screw is related to the filler content: – For ≤100 parts calcium: 1-2 years – For 100-200 parts calcium: ~1 year – For 200-300 parts calcium: 6-8 months – For >300 parts calcium: 3 months 2.Influence of Screw Structural Characteristics on Pipe Processing and Mechanical Properties **Requirements for Screw Structure Based on Filler Content** – >120 parts: Smaller metering section gap, increased mixing grooves, and high-calcium screws. – <80 parts: High-calcium screws with reduced feed and metering section flight gaps. – <30 parts: Feed mixing section and compression section combined, with larger metering section

1、 The material selection for the barrel screw is 38CrMoAlA, and the structural characteristics of several types of barrel screws are introduced as follows: Differences in conventional, low filler, and high filler structures (1) Geometric shapes and pairing relationships of screw edges and grooves Low CaCO3 content: larger between screw flights High CaCO3 content: The gap between the screw flights should be small, with the aim of improving shear force and increasing plasticization (2) The role of each regional segment. The screw is generally divided into: feeding section, compression section, blocking section, mixing section, exhaust section, and metering section. Feed section: Generally, the screw flights gap in the conveying section is large, resulting in fast conveying. Conversely, it is small. It is also related to the formula and CaCO3 components. Compression, blocking, and mixing: The main impact is on the plasticization ability. If there is no blocking before compression, plasticization can be increased. If there is a blocking, it is not suitable for high calcium. Mixing and compression are set together, usually only suitable for low calcium. Exhaust section: The plasticizing ability of the material can be observed from the vacuum port, which includes granular, powder, and strip shapes. Measurement section: If the screw flights clearance is large, the extrusion is fast, otherwise it is small. Introduction to the structural characteristics of low and high packing: The feeding section, compression, and mixing of the low packing screw are connected together. During machining, the last section of the feeding section has a

With the improvement of the production and processing technology of twin-screw extruders, they not only need to perform tasks such as feeding and plasticizing, but also have some requirements for dehydration, drying, etc. In order to better meet the different needs of users, twin-screw extruders must continuously improve their work efficiency and find ways to improve the quality of the manufactured products. So, how should we do it? Here are specific methods to improve production efficiency and product quality! How to improve work efficiency of twin-screw extruder: Improving work efficiency is one of the crucial goals in the development, design, and research of new co rotating twin-screw extruders. It can also be achieved by increasing screw speed, improving plasticization and mixing levels, and other methods. Expanding the depth of the screw groove can significantly increase the conveying capacity at the same screw speed. On the other hand, the plasticization and mixing level of the screw must also be increased, which requires the screw to be able to withstand higher torque. At high screw speeds, the residence time of the material in the extruder decreases, which may result in insufficient plasticization, melting, and mixing of the material. Therefore, it is necessary to appropriately increase the length of the screw, which will inevitably result in the twin-screw extruder actually carrying an increase in torque and power. Expanding the free volume of the screw groove is also a crucial factor. It is necessary for threaded components to have a large free volume in

International Plastics and Rubber Industry Exhibition will be held in Shanghai, China from April 23th to April 26th. Superior Machinery will participate in this exhibition. Booth No.:4.1B25 We look forward to meeting you there. ——Ningbo Superior Machinery Team

Best wishes to my friends, the Dragon Boat Festival happy to be joyful! ——Ningbo Superior Machinery Team  

International Plastics and Rubber Industry Exhibition will be held in COLOMBIA from  23st September to 27th September Superior Machinery will participate in this exhibition. Booth No.:2512B We look forward to meeting you there. ——Ningbo Superior Machinery Team

The dragon is a symbol of power, strength, and good luck in Chinese culture. May your family be blessed with happiness and harmony throughout the year. Happy Chinese New Year! from  SUPERIOR team

May the new year bring you peace, joy, and success in all your endeavors. Happy New Year 2025! –Ningbo Superior Machinery Team

Time flies, we are stepping to usher in the New Year. Thank you for your trust throughout the year, we keep the commitment to support our clients with high-level and high-precision products to meet their needs in the coming year. Happy 2024!