How to Improve the Surface Gloss of PVC-U Pipes and Profiles?-2

2.2 Mold Cavity Surface Precision  

The surface finish of the mold cavity directly determines product gloss:  

- Polishing to a roughness ≤Ra 0.2 μm is standard.  

- Electroplating the cavity improves gloss and extends mold lifespan.  

3. Strategies to Enhance Surface Gloss  

3.1 Optimize Formulation and Raw Materials  

- Ensure proper ratios of stabilizers, modifiers, and lubricants for thermal stability and flow.  

- Use nano-sized CaCO₃ fillers to significantly boost gloss.  

- Source high-quality raw materials from certified suppliers and conduct rigorous incoming inspections.  

3.2 Mold Design and Manufacturing  

- Design expansion angles and compression ratios to improve gloss.  

- Apply rapid cooling in calibration molds for a 6–7 point gloss improvement.  

- Use electroplated molds with Ra ≤0.2 μm roughness.  

- Incorporate “gloss retention plates” at mold inlets and optimize cooling/adsorption channels.  

3.3 Adjust Extrusion Parameters  

- Raise melt temperature moderately (1–2 points improvement) but avoid extremes.  

- Ensure balanced plasticization by optimizing barrel temperatures and screw speed.  

- Add a dedicated heating zone (~10 mm) near the die exit for finer gloss control.  

3.4 Equipment Selection  

- Screw design and barrel clearance critically influence plasticization and gloss.  

- Molds made of Mo-containing alloy steel (domestic or imported) achieve high gloss (up to 10 points) and durability at competitive costs.  

Conclusion  

Surface gloss optimization requires a holistic approach, balancing formulation, mold engineering, process tuning, and equipment selection. Prioritize high-quality materials, precision molds, and controlled extrusion parameters to achieve consistent, high-gloss PVC-U products.  

(The End)