What is Pultrusion in Injection Molding?

What is Pultrusion in Injection Molding?

In the pultrusion process, we always get a continuous fiber, and the strength of the product is excellent because of the constant fiber reinforcement. The name of the pultrusion process is similar to extrusion. Unlike extrusion, during pultrusion, we are going to pull the product on the opposite side. Let's discuss the necessary intricacies of the process:

  • Pultrusion process is an automated process for manufacturing composite materials into continuous cross-section profiles. The cross-section that we achieve from the process of pultrusion would be uniform.

  • It was developed around 1950 for making fishing rods of glass fiber reinforced polymer (GFRP). In this case, the reinforcing agent will be the glass fiber, and the matrix will be polymer.

  • It is usually grouped into two categories, namely: solid rod and bar stock and structural profiles.

  • Raw materials used for the pultrusion process are basically reinforcement fibers like: E-glass, S- glass, graphite/carbon, aramid having forms: roving, mat, fabric. Generally, the fibers are in the form of roving.

Matrix is generally in the form of polyesters, phenolics, polyvinyl esters, polyamides, and epoxy resins. Through the names of matrices, it can be understood that the pultrusion process generally requires thermosetting. Following steps are required for the pultrusion process:

  • Reinforcement handling system (creel): creel is used to mount the rovings from which we get the first pultrusion process requirement. Reinforcement can be in terms of fibers that can be woven on the creel. And this creel will help us to get our fiber for the process.

  • Resin impregnation station: we need a resin tank, which is also called the resin impregnation station. Here, the fibers will get wet and impregnated with the help of the matrix or resin.

  • Material forming area: we need to get the particular product's shape because the fibers are random. To give that shape, we need a material forming area.

  • We need components that heat and consolidate. Giving shape does not make the product ready. We need to give heat, pressure, and consolidation to the product. So it becomes solidified and rigid with a perfect shape.

  • Equipment to pull the protruded part: Since in the pultrusion process, a mechanism is needed to pull the product out of the machine. Thus, such equipment is required to make the pulling arrangement.

  • Equipment to cut the pultruded part: In pultrusion, we produce long fibers of cross-sections. So, we need to have a cutting machine so that we can cut lengths as per our requirement.


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