How is the PVC fence made? What’s called Extrusion?

The PVC fence is made by double screw extrusion machine.

PVC extrusion is a high speed manufacturing process in which raw plastic is melted and formed into a continuous long profile. Extrusion produces products like plastic profiles, plastic pipes,  PVC deck railings, PVC window frames, plastic films, sheeting, wires, and PVC fence profiles, are widely used in many fields.

This extrusion process starts by feeding PVC compound from a hopper into the barrel of the extruder. The compound is gradually melted by the mechanical energy generated by turning screws and by heaters arranged along the barrel. The molten polymer is then forced into a die, or called extrusion moulds, which shapes the PVC compound into a specific shape, such as fence post, fence rail, or fence pickets that hardens during cooling.

In the extrusion of PVC, the raw compound material is commonly in the form of powder that are gravity fed from a top mounted hopper into the barrel of the extruder. Additives such as pigment, UV inhibitors and PVC stabilizer are often used and can be mixed into the resin prior to arriving at the hopper. Therefore, as far as PVC fence production, we suggest our customers to stay with only one color in one order, or that cost of changing extrusion molds would be high. However, if customers have to have colored profiles in one order, details can be discussed.

The process has much in common with plastic injection molding from the point of the extruder technology, although it differs in that it is usually a continuous process. While pultrusion can offer many similar profiles in continuous lengths, usually with added reinforcing, this is achieved by pulling the finished product out of a mold instead of extruding the polymer melt through a mold. In other words, fence profile lengths, such as posts, rails, and pickets, they all can be customized in a specific lengths. For examples, a full privacy fence could be 6ft height by 8 ft width, it could also be 6ft height by 6 ft width. Some of our customers, they buy raw fence materials, then cut into specific lengths in their workshop, and fabricate different specification fences to meet all their customers needs.