What is PULTRUSION?
Pultrusion (from the English words: pull + extrusion) is:
- a technology that is the equivalent of extrusion applied, in this case, to composite/fiberglass material
- a continuous process which is ideal for high-volume industrial production
- adapted for making constant section straight profiles without length limits
Traditional pultrusion technology produces unique results that are aimed at users who need composite profiles with high performance in a longitudinal or lengthwise direction. Today, however, reinforcements in the form of fabrics with differentially-oriented fibres and strong polymers are available. This allows designing and producing profiles with extremely enhanced characteristics in directions other than longitudinal.
Pultrusion technology is by nature economically advantageous when it is done on a large scale and when long pieces are needed (limits to length are not technological but logistical). It is also indicated, of course, when the inherent, multiple physical and mechanical features of composite materials are desired.
DIFFERENT STAGES OF PULTRUSION PROCESS
1. IMPREGNATION STATION
The production process involves bringing together reinforcing fibres, according to the specified requirements of the process and final product. This occurs through in an impregnation station.At this stage, the fibres come into contact with a polymer matrix containing the base resin, additives, catalysts, pigments and mineral fillers and are thoroughly impregnated with them.
2. PROFILE CONFIGURATION
The sequence requires that the impregnated fibres go through an area where they are preformed, taking on the structural configuration and final shape of the desired profile section.
3. INSERTION INTO MOULD
The preformed material passes into a heated mould where a polymerization reaction occurs. This generates a transition into a polymer matrix phase going from liquid to solid.
4-5. PULTRUSION AND CUT
Once in a solid state, a pulling mechanism grips the profile area by means of special devices and directs it continuously to the last station, which cuts the profile according to a predefined length.