Bending Pultrusion Process

 

Pultrusion is a process for producing polymer-based composites in the form of a continuous long product of constant cross-section. The process is characterized by its automation and high productivity.

 

It is a very fast and economical method for impregnation and curing of materials, and the resin content after molding can be precisely controlled. In addition, since the resin impregnation area can be closed, volatile emissions can be limited. The scheme of the process is shown in the figure:

 

The Pultrusion Process Involves The Following Operations:

 

• The reinforcement fibers are pulled from the creel, which can be followed by a mat or fabric creel, and the pulling action is controlled by a pulling system.

 

• Guides collect the fibers into bundles and then guide them into the resin bath.

 

• The fibers enter the resin bath, where they are immersed in liquid resin. The liquid resin contains thermosetting polymers, fillers, catalysts and other additives.

 

• The wet fibers leave the melt pool and enter the preformer, where the excess resin is squeezed out of the fibers and the material is formed.

 

• The preformed fibers pass through a heated die, where the final cross-sectional dimensions are determined and the resin is cured.

 

• The cured product is cut into the required length by a cutting tool.

 

The Pultrusion Process has the Following Characteristics:

 

• High productivity.

 

• Easy to control process parameters.

 

• Low labor costs.

 

• Accurate cross-sectional dimensions of the product.

 

• Good surface quality of the product.

 

A uniform distribution and high concentration of reinforcing fibers in the material are achieved (up to 80% roving reinforcement, up to 50% hybrid mat + roving reinforcement).

 

Due to the characteristics of the process, pultrusion is generally limited to constant or near-constant cross-section components, and the cost of heating the mold can often be high.

 

Pultrusion is used in the manufacture of glass fiber, carbon fiber reinforced polymer composites and Kevlar (aramid) fiber reinforced polymers. Some typical common structural applications include: beams and girders for roof structures, bridges, ladders, frames.