Pultrusion is a continuous process of producing composite profiles from the fibrous reinforcements and heat-reactive polymers. The reinforcements are unwound from racks and pass through a bath, where they are soaked in an impregnating mixture. This is followed by draining the excess impregnation mixture and creating a profile design. Such designed and impregnated fibres move through a metal tool, which has an opening cut out lengthwise in the form of a profile. The tool is heated. The thermosetting resin in the tool makes a grid. From the resulting hardened tool profile. The pultrusion system which follows the tool provides a uniform movement of the impregnated fibres and hardened profile along the pultrusion line. There is a saw at the end which cuts the profile to a certain length.
Fibrous reinforcements which are used for pultrusion profiles, are usually made of glass fibres in the form of a roving. To increase strength in a transverse direction, mats, fabrics and combined reinforcements are added. Also reinforcements from other types of fibres are used.
We use mostly E glass fibres and carbon fibres. With a wrapping unit, which is placed in front of the tool, it is possible to integrate layers of roving also in a transverse, tangential direction in pipes and other hollow profiles.
The impregnating mixture is composed of thermosetting resin as well as technological and functional additives. We mostly use unsaturated polyester resins, epoxy resins and vinyl ester resins.
The external dimensions of the pulled profiles range from a millimetre to a few tens of centimetres. The profiles have smooth surfaces, they may be pigmented and have small dimensional tolerances. They are lightweight, corrosion-resistant and have good mechanical properties. Glass fibre profiles are good electrical insulators and have a low thermal conductivity. Carbon fibre profiles are even lighter and are characterized by an increased rigidity and strength.
The good characteristics of pulled profiles are shown in a number of fields. Some of these are: the electrical industry, sports, chemical industry, agriculture and construction. With a proper selection of output materials, it is possible to adjust the profile features to the needs and conditions of use.
The production of pulled profiles started in our company or in the legal precursors of the company in the mid 1960s. At that time, the first traction machine was produced. First, production was focused on its primary functions, and later it expanded to other areas as well.