[to be continued ‘production methods’]

SMC (Sheet Molding Compound)

a molding composition, is much more similar to automated and continuous processes. It is characterized by medium-high production rates, a stable section and precise and codified tolerances. It originates from a resin impregnated mat (prepregs) formed of short free-fall fibers. The composite is placed inside an aluminium mold under forming press. In this way it undergoes a process of polymerization (‘curing’) that changes the physicality of the material. Therefore a controlled and repetitive process is generated, by which it is always possible to obtain the same result. Then the mold is closed and sealed under pressure and air is drawn in during the curing. It is destined for the production of medium sized elements.

BMC (Bulk Molding Compound)

is similar to the previous process, in which the composite is used in the form of ‘prepreg paste mass’; it can be processed using processing methods, such as, moulding, transfer or direct injection inside the mold. This technique is also destined for the production of small-medium sized elements.

Pultrusion

a system for the continuous pull extrusion of profiles with a stable section and straight axis, with subsequent curing in the heated closed die. The use of long fibers provides resistance to the product and mechanical responses similar to those which are typical for steel, except for the isotropy of material (the Pultruded Profile is highly orthotropic). Therefore the production is steady and automated; the dies used are made of hardened steel and ensure high production rates, thanks to their very high resistance. At the end of the process the product is cut to the desired length. Examples: IPE profiles, squared profiles, round profiles and profiles with complex shapes.

[Coming up ‘Behaviour of the GFRP composite material’]