عربىAt a time when the manufacturing industry is pursuing green transformation, the problem of material waste of up to 15%-30% in plasticizing processes such as injection molding and extrusion has always plagued companies. In recent years, a technical solution called Conical Screw Barrel has attracted attention in the fields of automotive parts, packaging materials and electronic components. Data shows that production lines using this design can reduce raw material loss by 8%-12% and improve energy efficiency by more than 15%. How does this breakthrough design achieve energy saving and efficiency improvement?
Principle analysis: The "progressive compression" advantage of conical structure
Compared with traditional parallel screws, the core innovation of conical screw barrels lies in their gradual geometric structure (Figure 1). The screw diameter gradually decreases from the feed end to the discharge end, forming a continuously reduced thread channel. This design optimizes material handling in three stages:
Efficient pre-compression: The larger volume of the feed section allows for rapid inhalation of granular raw materials, while the gradually narrowing screw groove generates progressive pressure during the conveying process, avoiding material accumulation or backflow caused by sudden pressurization;
Precise shear control: The conical structure makes the shear rate gradient of the melting section smoother, and with the precise tolerance of the screw gap (usually controlled at 0.05-0.1mm), it can fully melt the polymer material and prevent thermal degradation caused by local overheating (Thermal Degradation) - one of the main factors leading to waste generation;
Dynamic sealing effect: The smaller diameter of the discharge end enhances the sealing of the barrel and the screw, reducing the melt reflow rate to less than 0.5% (parallel screws are usually 2%-5%), significantly reducing the residual material that is not fully extruded.
Empirical data: Industrial case of energy consumption and waste reduction
A comparative test conducted by KraussMaffei, a German injection molding equipment manufacturer, on the production of automotive PP bumpers in 2023 showed that after using a conical screw barrel, the raw material loss per ton of product dropped from 43kg to 36kg, while the unit energy consumption was reduced by 18%. This is due to two aspects of optimization:
Residence time is shortened by 22%: The compression ratio of the conical screw (usually 3.5-4.5:1) is higher than that of the parallel screw (2.5-3:1), which accelerates the transformation of the material from solid to molten state and reduces the risk of molecular chain breakage caused by long-term heating;
Improved melt uniformity: Through ANSYS Polyflow simulation, it was found that the standard deviation (SD) of the melt temperature of the conical structure was 2.3°C, which was better than 5.1°C of the parallel screw, which means fewer hot spots and cold material defects.
Technical extension: Compatible with recycled materials and bio-based plastics
With the advancement of circular economy policies, the manufacturing industry has a surge in demand for the processing of recycled plastics (rPET, rPP, etc.). The mild plasticizing characteristics of the conical screw barrel (peak temperature is reduced by about 10-15°C) can reduce the thermal decomposition of impurities in the recycled material, so that when processing a mixture containing 30% recycled material, the qualified rate of the finished product can still be maintained at more than 98%.
