What are the challenges in achieving smooth surfaces on WPC outdoor trash cans during manufacturing?

Achieving a perfectly smooth surface on Wood Plastic Composite (WPC) outdoor trash cans during manufacturing presents several significant challenges. The inherent nature of WPC material, which combines wood flour/fibers with thermoplastics, is a primary factor. The organic wood particles can absorb moisture and have varying sizes, leading to surface inconsistencies like roughness, swelling, or the "orange peel" effect upon extrusion. The extrusion process itself is critical; improper control of temperature, pressure, and screw speed can cause defects such as melt fracture, die lines, or incomplete fusion, resulting in a wavy or uneven surface. Furthermore, the flow of the WPC melt within the mold is complex. Inadequate mold design, especially around corners and complex shapes of a trash can, can lead to flow marks, weld lines, and uneven material distribution. Finally, post-extrusion finishing is limited. Unlike pure plastics, WPC cannot be easily melted and polished, and sanding can expose wood fibers, compromising water resistance. Overcoming these challenges requires precise material formulation, optimized processing parameters, and sophisticated mold design to ensure a high-quality, durable finish for outdoor use.