How to ensure dimensional accuracy when producing WPC profiles?

The dimensional accuracy of WPC profiles directly affects the splicing and installation effect, surface flatness, and product qualification rate. Due to the characteristics of its production process, such as the presence of wood powder as filler, high melt viscosity, and easy deformation during molding, Yongte WPC equipment implements precise control throughout the entire process, from raw material pretreatment, equipment parameters, mold design, cooling and shaping, traction cutting, and online monitoring, to ensure the dimensional accuracy of WPC products. Specific measures are as follows:

1. Strict Control of Raw Material Pretreatment and Proportion Stability

1.1 Wood Powder Drying and Moisture Content Control: Wood powder is a key factor affecting dimensional accuracy. Excessive moisture content can lead to air bubbles and melt foaming during extrusion, causing uneven wall thickness or dimensional distortion in the profiles. Wood powder must be dried in a hot air dryer to a moisture content of **≤0.3%**, at a drying temperature of 80-100℃ for 2-3 hours; after drying, it must be stored in a sealed container to prevent moisture regain.

1.2 Precise and Stable Raw Material Proportions: Wood-plastic composite (WPC) flooring commonly uses PE/PVC as the base resin, with wood flour typically added at 40%-60%. Strict adherence to the formula is crucial; an automated weighing and batching system is recommended to avoid manual proportioning errors. Simultaneously, lubricants, compatibilizers, and other additives must be thoroughly and uniformly mixed to prevent uneven flow rates due to localized melt viscosity differences, which could lead to dimensional deviations.

Preventing Raw Material Degradation: The residence time after mixing wood flour and resin must be controlled to prevent carbonization of the wood flour or degradation of the resin at high temperatures, affecting melt flowability and stability.

2. Optimizing Extrusion Equipment Parameters to Ensure Stable Plasticization and Conveying

2.1 Yongte's Configuration of Extruders Suitable for Wood-Plastic Composites: Wood-plastic composite melts have high viscosity, requiring a high-torque conical twin-screw extruder (screw diameter selected according to profile cross-section size, such as φ65/132, φ80/156). This extruder offers stronger plasticizing, mixing, and conveying capabilities, reducing melt pressure fluctuations. Avoid using single-screw extruders, as this can easily lead to uneven plasticization and unstable extrusion volume.

3. Precise Control of Extrusion Temperature and Speed

3.1 Temperature Segment Settings (Taking PE-based wood-plastic composites as an example): Feeding section 120-140℃, Compression section 150-170℃, Homogenization section 160-180℃, Die head temperature 170-185℃; For PVC-based wood-plastic composites, the temperature needs to be reduced by 5-10℃ to prevent thermal degradation. Yongte is equipped with a precise temperature control and automatic temperature control system, controlling temperature fluctuations within ±2℃ to avoid sudden changes in melt viscosity.

3.2 Stable Screw Speed: Yongte is equipped with a variable frequency speed control system + melt pressure sensor to monitor die head pressure in real time (fluctuation range ≤ ±0.5MPa). When the pressure is abnormal, the speed is automatically adjusted to ensure a constant extrusion volume.

4. Strengthen Mold Design and Precision Control to Ensure Molding Consistency

4.1 Optimization of Flow Channels in Irregular Profile Molds: Wood-plastic flooring profiles have irregular cross-sections. Yongte's mold flow channels adopt a gradient design to ensure uniform melt flow velocity across the mold head, avoiding uneven wall thickness, warping, or problems caused by excessively fast/slow local flow rates. The mold head's shaping section is long enough to ensure complete melt molding.

4.2 Mold Precision and Maintenance: Yongte controls mold cavity dimensional deviations within ±0.03mm, and polishes the cavity surface to Ra≤0.8μm to prevent melt adhesion. Yongte recommends operators regularly check the mold's concentricity and levelness, and calibrate the coaxiality of the mold head and shaping mold to prevent profile distortion.

4.3 Equipped with Flow Diverters and Baffles: Yongte equips flooring molds with complex cross-sections with flow diverters and baffles to balance melt flow in different areas, ensuring uniform profile cross-sectional dimensions.

5. Precise Control of Cooling and Calibration Process to Eliminate Internal Stress Deformation

5.1 Segmented Gradient Cooling: The cooling water temperature is set in a gradient: 30-40℃ in the first segment (to avoid sudden cooling and internal stress), 25-30℃ in the middle segment, and 20-25℃ in the last segment, gradually reducing the profile temperature. The shaping table is 8 meters long, ensuring the profile temperature drops to ≤45℃ when exiting the shaping table for complete shaping.

5.2 Uniform Distribution of Cooling Water Channels: The water channels inside the shaping mold are evenly distributed to avoid profile warping and dimensional deviations caused by uneven cooling in certain areas.

6. Synchronous Traction and Precise Cutting to Control Length and Straightness

6.1 Precise Speed Control of the Traction Machine: A dual-track synchronous traction machine is used, ensuring uniform clamping force and preventing surface damage or deformation of the profile. The traction speed and extrusion speed can be synchronized, with speed fluctuations controlled within ±0.5%.

6.2 High-Precision Chipless Cutting: A CNC positioning cutting machine is used. Before cutting, ensure the profile is completely fixed, and control the cutting length deviation within ±1mm. The cutting machine is equipped with a clamping device to prevent profile displacement or rotation, and to prevent uneven ends.

6.3 Regular Sampling Inspection: According to GB/T 24508 standard requirements, sample and measure the profile cross-sectional dimensions every 30 minutes. Width deviation should be controlled within ±0.3mm, thickness deviation within ±0.2mm, and warpage ≤0.5mm/m. Adjust process parameters promptly if deviations are found.

7. Equipment Maintenance and Environmental Management to Reduce External Interference

Regular Equipment Maintenance: Wood flour is abrasive. Yongte recommends that operators regularly check the wear of the screw and barrel, and repair or replace them promptly; clean residual material from the mold flow channel to prevent material accumulation from affecting melt flow; check the wear of the traction machine's rubber rollers to prevent slippage.

Stable production environment: Workshop temperature is controlled between 18-35℃, and humidity ≤60%, avoiding fluctuations in temperature and humidity that could affect cooling and shaping. Extruded profiles must be laid flat on a dedicated support to prevent excessive stacking and deformation.

Summary:

Yongte's wood-plastic composite WPC production equipment ensures dimensional accuracy of wood-plastic flooring profiles through comprehensive process control including "stable mixing and plasticizing, precise mold forming, gradient vacuum shaping, synchronous traction cutting, and real-time monitoring," keeping key indicators such as cross-sectional dimensions, straightness, and warpage within standard ranges.