Die is an important tool of pultrusion technology, generally composed of two parts: preform die and forming die.

① Pre-forming die In the pultrusion process, after the reinforcement material is impregnated with resin (or impregnated at the same time), before entering the forming die, it must pass through a pre-forming die composed of a group of yarn guide elements. The function of the pre-forming die is to gradually form the pre-formed body with approximate molding mold control shape and size according to the configuration form of the profile section, and then enter the forming die, so as to ensure uniform yarn content of the product section. The ratio of the cross-sectional area of the molding die to the cross-sectional area of the product should generally be greater than or equal to 10 to ensure that the mold has sufficient strength and rigidity, and the heat distribution is uniform and stable after heating. Pultrusion mold length is determined according to the traction speed and resin gel curing speed in the molding process to ensure that the product reaches the degree of demoulding curing when pulled out. Generally, steel chrome plating is used, and the surface of the mold cavity is required to be smooth and wear-resistant, so as to reduce the friction resistance of pultrusion and improve the service life of the mold.