Pultrusion technology is to soak glued continuous roving, mat, or cloth reinforced materials under the traction,go through mould heating, solidifying, unlimited length of continuous profiles are produced successfully, it is suitable for mass production with simple but regular FRP profiles and pipes.
FRP pultrusion mouldis the important tool in pultrusion technology, molding the ratio of the cross sectional area between mould and product generally should be ≥10, to guarantee that the mould have enough strength and stiffness, and the uniformity and stability of heat distribution after mould being heated. The length of mould is determined by the speed of traction and the solidification speed of resin gel in the process of molding,the purpose is guarantee the products have been solidified when out of mould. In general, the mold is made by chrome plating, the surface of mold cavity is clean and wear-resisting, so as to reduce the friction resistance and improve the service life of the mould.
Fibergalss Pultruded moulds /Tooling assembled by several pieces. When designing a mould, the principle to select the parting surface is to reduce the fractal surface to ensure the tight fitting of the mold. The thermal parameters, clamping speed and traction are the primary factors that should be solved in the pultrusion process. The principle of pultrusion speed is the gelation time at the temperature inside the mould, to let products is gelatinized and solidified in the middle of the mould.
There are many factors to restrict traction, such as:
1) Mould temperature and pultruded speed.
The increase of the speed will affect the second peak of shear stress directly , which named the shear stress at the disengagement point;
2) The mold release agent is also an important factor.
In order to improve production efficiency, it is generally possible to improve pultrusion speed. But it will reduce the shear stress and the surface quality of the products. It should decrease the producing speed for thicker products, or to change a longer mold instead, increasing the temperature of FRP pultrusion moulds/tooling, is aimed to make our products solidified more better, so as to improve the performance of products.
