The pultrusion process is a method for continuously producing composite profiles by impregnating the crepe-free glass fiber rovings and other continuous reinforcing materials, polyester surface felts, etc., and then going through the shape of the cross-section. And it is continuously extruded after molding in the mold, thereby forming an automated production process of the pultrusion product.

Products produced by the pultrusion process have higher tensile strength than ordinary steel. The resin-rich layer on the surface makes it have good corrosion resistance, so it is the best substitute for steel in engineering with corrosive environment. It is widely used in transportation, electrical, electrical insulation, chemical industry, mining, ocean, boats, corrosive environment and life, civil use in all fields.

The pultrusion process：

The pultrusion processes have many classification methods, such as batch and continuous, vertical and horizontal, wet and dry, crawler traction and gripping traction, in-mold curing and in-mold gel mold out-mold curing, heating method with electric heating, infrared heating, high frequency heating, microwave heating and combined heating.

The typical process of pultrusion is:

Glass fiber roving arrangement – dipping – preforming – extrusion molding and curing – traction – cutting – products

Pultrusion equipment

1 Reinforced material conveying system: such as creel, felt spreader, yarn hole, etc.

2 Resin impregnation: straight trough dipping is most commonly used. During this impregnation process, the fibers and felts should be arranged neatly.

3 Pre-forming: The impregnated reinforcing material passes through the preforming device and is carefully conveyed in a contact manner to ensure their relative position, gradually approaching the final shape of the product, and extruding excess resin before entering the mold to form shape and cure.

4 Mold: The mold is designed under the conditions determined by the system. According to the resin curing exotherm curve and the friction properties of the material and the mold, the mold is divided into three different heating zones, the temperature of which is determined by the performance of the resin system. The mold is the most critical part of the pultrusion process, with typical mold lengths ranging from 0.6 to 1.2 m.

5 Traction device: The traction device itself can be a crawler type puller or two reciprocating clamping devices to ensure continuous motion.

6 Cutting device: The profile is cut by a cutting saw that is automatically synchronized and moved to the required length.