PRODUCTION PROCESSES

processo

Since 1963, Top Glass has made its composite products using systems designed and built entirely inside the company. This has been possible due to the exclusive know-how which it has developed over the course of its fifty-year history.
The three main technologies used are as follows

 

 

Pultrusion (from the English words: pull + extrusion) is:

  • - a technology that is the equivalent of extrusion applied, in this case, to composite 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.

THE PRODUCTION PROCESS:

 macchina pultrusione

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(1).

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.

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 (2).

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 (3).

Once in a solid state, a pulling mechanism (4) 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 (5).

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.

 

Centrifugal casting is a production technology used to make composite poles (with fibreglass) in the shape of a truncated cone (TAPERED POLES) with maximum length, set only for logistical constraints, of 13.6 metres.

The pole is formed by inserting the reinforcement (fibreglass) in a specific rotating mould that has a truncated-cone cavity. Due to centrifugal force, the fibreglass adheres to the walls of the mould and takes its shape.
The matrix (resin) inside the mould is impregnated with fibreglass due to the rapid rotation of the mould (centrifugal casting). It also hardens by polymerizing when it comes in contact with the heated mould..

The poles produced by centrifugal casting can have constant or differentiated thickness due to the possibility of controlling the distribution of the reinforcement inside the mould. This way, tapered poles are obtained which are reinforced only in the critical areas determined by their use. This is accomplished without increasing thickness and thus weight over the entire length.

The raw materials used in this process are the same as in pultrusion: resins and fibreglass reinforcements.

This technology makes it possible to make products with a high degree of dimensional and physical-mechanical repeatability. These poles find wide use, for example, as lighting poles and supports for electricity, telephone and over-head lines.

 

PULLWINDING technology is used for producing tubular profiles with superior rigidity and mechanical resistance.

This production process differs from traditional pultrusion with respect to way the fibreglass is positioned for reinforcing the profile. In traditional pultrusion, reinforcement with fibreglass is done in a combined way using roving (unidirectional fibres), mat (continuous multi-directional fibres) and woven fabric (with a warp and woof). Pullwinding, used to create tubes, differs from traditional pultrusion in that it uses both roving placed longitudinally and circumferentially with respect to the profile's axis.

In pullwinding, the structure obtained after polymerisation in the heated mould (the same kind as used in traditional pultrusion) has, however, superior rigidity due to the varying orientations of its reinforcements.