COMPOSITE INFUSION, WHAT IS IT?
Composite infusion consists in placing under vacuum composite fibers that will be impregnated with resin thanks to the vacuum created in the mold. Indeed, the vacuum is made by using a mould closed by a tarpaulin where the glass or carbon fibers have been previously placed.
The composite infusion process is nowadays mainly used for large parts. In fact, it is widespread in the naval world for infusion of large boat hulls.
Moreover, the use of this process allows to use the right amount of resin required. We therefore obtain a part with a better strength/weight ratio.
Finally, with respect to contact molding, composite infusion provides better protection for operators against solvent emissions.
Setting up such a process can be complicated. Indeed, it is necessary to ensure a perfect seal so that the resin can infuse all the composite fiber fabrics. It is therefore important that it is carried out by experienced people.
This type of process also generates waste (consumables), unlike the carbon prepreg process.
COMPOSITE INFUSION, TECHNIQUES
INFUSION BETWEEN REINFORCEMENTS
We can inject the resin directly between two layers of reinforcements. We do not use this technique because there is a risk of poor impregnation of the composite fibers.
This is the most widely used technique. To do this, we come to place a draining cloth on the entire surface of the piece to be infused. The latter will distribute the resin on the cloth. The choice of the draining cloth will allow to modify the speed of propagation of the resin, the viscosity, …). Unlike manual lamination, the impregnation of the structure by vacuum infusion will take place in one go and not by reinforcement. The vacuum infusion of the assembly will allow a perfect plating of the composite reinforcements against the mould surface and obtain a part with a high glass fiber content for a good resin ratio.
COMPOSITE INFUSION, MATERIALS
As mentioned, composite infusion also uses different consumables and therefore waste afterwards:
- Tear-off fabric: this is a textile web made of polyamide or polyester that will allow the part to be removed from the mould. This fabric allows a finished surface state to be obtained according to the weight of the part.
- Separator film: this is a very thin plastic film that is placed under the drain to facilitate the removal of the drain after polymerization.
- Draining fabric: this is a net that guides and distributes the resin over the entire part.