The reasonable selection of plastic pelletizing process parameters is crucial to improve pelletizing quality and production efficiency. This article mainly optimizes the pelletizing process parameters of common thermoplastic plastics PP, PE, ABS and other materials from three aspects: raw material pretreatment, extrusion pelletizing and pelletizing process, through the method of combining theoretical analysis and actual experiments.

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  1. Raw material pretreatment process optimization

Raw material pretreatment is to crush various plastic raw materials into particles suitable for extrusion pelletizing. Key process parameters include pre-mixing time, crushing mesh, etc. The experiment adopts PP material to investigate the effect of pre-mixing time on flocculation. The results show that the optimal pre-mixing time is 8min, too long will lead to material degradation. The optimal crushing mesh is 40 mesh. Too large will affect mixing effect and too small will increase energy consumption.

  1. Extrusion pelletizing process optimization

In the extrusion pelletizing process, the barrel temperature directly affects the melt quality. Experiments show that 150°C/170°C/190°C is optimal for PE material. The screw speed affects the conveying capacity and shear force, 100rpm is a suitable speed. The die hole diameter of 2-3mm is appropriate to ensure smooth pellet discharge.

  1. Pelletizing process parameter optimization

Wet pelletizing utilizes water ring cooling, and adds a certain proportion of modifier, so that plastic pellets generate micropores during mixing, increase the surface area, facilitate cooling, and thus obtain full and round pellets. The key parameters are water temperature, agitation speed and dosage of modifier. For PP material, when the water temperature is 15-20°C, the agitation speed is 300rpm, and 1%-2% modifier is added, pellet products with ideal sphericity greater than 95% can be obtained.

In summary, in order to obtain ideal pelletizing effects for different plastics, the process parameters must be optimized according to the material type. The extrusion temperature directly affects the melt fluidity, and agitation cooling is crucial for the pelletizing effect. This study provides important process parameter selection basis for plastic pellet production.