Precautions for PVC Fittings Injection Molding Process: Focus on Material

1. Use Appropriate Injection Molding Equipment
   PVC water supply pipe fittings are typically molded using screw-type injection machines instead of plunger-type, ensuring uniform plasticization and minimizing adverse effects on the PVC melt. Parts of the machine that contact PVC should be treated for corrosion resistance to prevent corrosion and avoid adherence of the plastic melt, ensuring product quality and equipment longevity.

2. Keep Raw Materials Clean and Avoid Cross-Contamination
   It is critical to prevent contamination of PVC pellets with other plastic materials (e.g., polyethylene, polypropylene) during the injection process, as this degrades PVC quality and affects finished product performance. When switching materials, thoroughly clean the barrel and screw, preferably using cleaning materials like polyethylene or polystyrene, to avoid residue contamination of PVC raw materials.

3. Strict Control of Raw Material Storage and Drying
   PVC pellets are sensitive to moisture; damp materials easily cause bubbles and defects during processing. Thus, materials must be kept dry, stored in a dry and ventilated environment with sealed containers, and regularly inspected to ensure stable raw material quality.

4. Proper Temperature and Process Settings
   The heating temperature for PVC should be strictly controlled within the recommended range. Excessive heat may degrade and discolor PVC, while too low temperature adversely affects plasticization and flowability. Appropriate temperature, injection speed, and holding time are key to achieving proper melt and dimensional stability of the product.

5. Avoid Extended Residence Time and Thermal Degradation
   PVC raw materials left too long in the barrel may undergo thermal degradation, releasing harmful gases and causing color changes, which directly impair product quality. Operations should minimize the residence time of material in the barrel and avoid prolonged exposure to high temperatures.

These precautions help ensure the material properties of PVC water supply pipe fittings are fully utilized during injection molding, guaranteeing product quality and safety.