Common problems and solutions in WPC door extrusion production

Xinhe Machinery has actual door panel manufacturing clients in countries such as Saudi Arabia, Vietnam, Jordan, and Iraq. We provide technical support from raw materials to finished products, helping clients grow from zero to over a dozen door panel and frame production lines. We have extensive experience in door panel production. We have summarized common problems and solutions in WPC door extrusion production, mainly involving three aspects: process, equipment, and materials:

I. Process Issues

1. Paste

Causes: Poor thermal stability of PVC resin, improper selection of stabilizers in the formula, improper ratio of the three lubricants (the three lubricants have different effects at different times, so all three must be selected), or unreasonable control of process parameters (such as temperature, screw speed, and die pressure).

Solutions: Optimize the formula, select appropriate stabilizers and lubricants, control the moisture content and low volatile content of raw materials, and adjust process parameters to a reasonable range.

2. Surface Defects

Manifestations: Poor gloss, insufficient skin hardness, scratches, dents, dark/bright bands, cracks, or impurities.

Solution: Adjust the process to ensure stable parameters such as temperature and pressure.

3. Mismatch between traction speed and extrusion speed

Impact: Leads to uneven wall thickness, inconsistent tolerances, and even affects physical and mechanical properties.

Solution: In twin-screw extruders, for wall thickness <1mm, the screw speed should be 20~25 r/min and the traction speed 3~4.5 m/min; for wall thickness >2mm, the screw speed should be 15~20 r/min and the traction speed 0.6~1.5 m/min.

II. Equipment Problems

Excessive die head pressure

Impact: Leads to slow extrusion speed, affecting output.

Solution: Optimize the die head design and adjust the screw speed and die head pressure.

Insufficient cooling

Impact: Profile deformation and surface ripples.

Solution: Use air cooling or a spray water tank for cooling to ensure the profile cools to room temperature.

3. Insufficient Extrusion Volume

1. Impact: Unstable product quality, high scrap rate.

2. Solution: Select different extruders for different door panel widths; generally, a 92/188 extruder is used. To reduce machine costs, door panels under 800mm wide can use an 80/156 extruder; if wider than 900mm, a 92/188 extruder must be used.

III. Material Issues

Excessive Wood Flour Content

1. Impact: Leads to poor product toughness and easy breakage.
2. Solution: Control the wood flour content to ensure good plasticization of raw materials and avoid impurities. Xinhe Machinery has concluded that the best wood flour content is 5%~10%, and it is best not to add wood flour at all. The reason it's called a WPC door is because it was originally designed for recycling wood. Currently, wood flour is relatively scarce, so not adding wood flour is the best choice and also reduces production costs.

Wood Flour Fading

1. Cause: Fading of resin, pigments, or wood flour itself, affected by environmental factors such as temperature, humidity, and light.
2. Solution: Use chemical methods to decolorize the wood flour initially, then dye it with pigments; or choose dark pigments and light-shielding agents (such as carbon black) to cover it up.

IV. Other Issues

1. Poor Internal Cavity Forming

1. Cause: Inappropriate mold design or process parameters.

2. Solution: Optimize mold design and adjust process parameters.

2. Low Static Pressure Bearing Capacity

1. Cause: Material formulation or process issues.

2. Solution: Optimize the formulation and adjust process parameters.