In the powder coating production process, the extruder serves as a key equipment for material melting, kneading and homogenization, and its performance directly determines the gloss, leveling property and stability of the finished coating. As the "core component" of the extruder, the screw undertakes core tasks such as material conveying, shear plasticization and pressure building, which is a crucial link to ensure production efficiency and product quality. YTOPSUN has been deeply engaged in the field of powder coating extrusion equipment for many years. With precise R&D and optimization of screw technology, it has created a series of high-performance extruders suitable for various powder coating production needs. Its screw design integrates three core advantages: material upgrading, structural innovation and process adaptation, becoming an industry technical benchmark.
I. Core Structure and Functional Zones of the Screw
The screw of a powder coating extruder is usually composed of four parts: feed zone, melting zone, mixing zone and metering zone. Each section works synergistically to convert materials from solid state to uniform molten state. Aiming at the characteristics of powder coatings such as easy adhesion and precise temperature control, YTOPSUN has customized the structure of each section of the screw, breaking the performance limitations of traditional screws.
The feed zone adopts a large screw groove depth design, and the width of the screw flight is accurately calculated, which effectively reduces material conveying resistance, ensures stable feeding of powder raw materials and avoids bridging. The melting zone adopts a linear decreasing design of screw groove depth, forming a gradient temperature field with the barrel heating system. Under the combined action of shear force and heat, the material is gradually melted, and volatile substances and moisture are discharged to lay the foundation for subsequent kneading.
The core innovation lies in the multi-angle screw block design of the mixing zone. YTOPSUN adopts a four-stage gradient screw block combination of 30°, 45°, 60° and 90°. Through the resistance difference of screw blocks with different angles, it realizes the graded treatment of materials from rough mixing to ultra-fine mixing. The 30° screw block is responsible for initial material dispersion, the 45° and 60° screw blocks enhance shear kneading, and the 90° screw block improves material homogenization, effectively avoiding coating scorching and uneven curing. It is especially suitable for the production of powder coatings with complex formulas such as flake raw materials. The metering zone adopts a shallow groove constant pitch design, which accurately controls the output flow and pressure of molten materials, ensures the consistency of extruded materials, and provides stable raw materials for subsequent tableting and crushing processes.
II. Material Upgrading and Wear-Resistant Anti-Corrosion Technology
In powder coating production, high-fill materials and abrasive raw materials are likely to cause screw wear, while heat-sensitive raw materials have high requirements for the smoothness of the screw surface. YTOPSUN solves the wear problem from the source, using CPM/W6Mo5Cr4V2 special alloy and 38CrMoAlA high-quality steel as the screw matrix, combined with bimetallic surfacing technology, forming a 0.3-0.5mm tungsten carbide alloy layer on the surface of the screw flight. After plasma nitriding treatment, the surface hardness can reach HV≥900, and the service life is 3-5 times longer than that of ordinary nitrided screws.
At the same time, YTOPSUN screws adopt precision CNC machining technology to ensure the surface roughness Ra≤0.4μm, reducing the risk of material adhesion and carbonization. Matching with centrifugally cast bimetallic barrels, it forms precise clearance fit, avoiding local wear and material leakage, and adapting to the long-term stable production of high-abrasive, high-fill and heat-sensitive powder coatings.
III. Key Parameter Optimization and Customized Adaptation
Length-diameter ratio (L/D) and compression ratio are core parameters determining screw performance, directly affecting material residence time and plasticization effect. According to the needs of different types of powder coatings, YTOPSUN provides customized parameter design: when producing heavy anti-corrosion powder coatings, screws with a length-diameter ratio of 12:1-14:1 are adopted to control the material kneading time within 20s, avoiding the decrease of film flatness caused by shortened gel time; for general-purpose powder coatings, the length-diameter ratio is optimized to 18:1-25:1 to improve plasticization uniformity; for heat-sensitive powders, the compression ratio is reduced to 2.5:1 to reduce shear heat generation and prevent material overheating decomposition.
In addition, the screw of YTOPSUN TSX series extruder is equipped with a torque limiter and an intelligent temperature control system to monitor the screw operation status in real time. When the torque increases by more than 15%, it automatically shuts down to avoid screw strain caused by foreign objects or overload; through the HMI interactive touch panel, the screw speed and temperature of each section can be accurately adjusted to realize rapid switching of multi-formula production, taking into account production efficiency and operational convenience.
IV. Screw Maintenance and Service Life Extension Strategies
Reasonable maintenance is the key to extending the service life of the screw. Based on years of application experience, YTOPSUN provides users with a full-cycle maintenance plan. Before starting, the barrel should be preheated to the process temperature and kept warm for 30-60 minutes, and feeding should be started at low speed (10-20r/min) to avoid dry grinding during cold start; when changing materials or shutting down, use special cleaning materials to clean the screw at low speed to remove residual materials and prevent carbonization; when shutting down for a long time, the screw should be coated with anti-rust grease and hung vertically to avoid deformation and rust. At the same time, it is recommended to regularly check the clearance between the screw and the barrel. When the clearance exceeds 0.3mm, repair it in time, and cooperate with material pretreatment (100-mesh screen sieving + strong magnetic separation for impurity removal) to reduce wear risk from the source.
V. Industrial Value of YTOPSUN Screw Technology
YTOPSUN has always focused on user needs, deeply integrating screw technology with powder coating production processes. The screws of its developed twin-screw extruders not only have excellent wear resistance and kneading effect, but also realize rapid component replacement and upgrading through modular design, adapting to different production scenarios such as small-batch customization and large-scale mass production. From general-purpose powders to heavy anti-corrosion and high-performance special powder coatings, YTOPSUN screw technology provides an efficient, stable and energy-saving solution for the industry, helping enterprises improve product competitiveness and promoting the development of the powder coating industry towards high quality and refinement.
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