Description
Fabrics are laid up as a dry stack of materials as in RTM. The fibre stack is then covered with peel ply and a knitted type of non-structural fabric. The whole dry stack is then vacuum bagged, and once bag leaks have been eliminated, resin is allowed to flow into the laminate. The resin distribution over the whole laminate is aided by resin flowing easily through the non-structural fabric, and wetting the fabric out from above.

Materials Options:
Resins: Generally epoxy, polyester and vinylester.
Fibres: Any conventional fabrics. Stitched materials work well in this process since the gaps allow rapid resin transport.
Cores: Any except honeycombs.

Main Advantages:

As RTM, except only one side of the component has a moulded finish.
Much lower tooling cost due to one half of the tool being a vacuum bag, and less strength being required in the main tool.
Large components can be fabricated.
Standard wet lay-up tools may be able to be modified for this process.
Cored structures can be produced in one operation.

Main Disadvantages:

Relatively complex process to perform well.
Resins must be very low in viscosity, thus comprising mechanical properties.
Unimpregnated areas can occur resulting in very expensive scrap parts.
Some elements of this process are covered by patents (SCRIMP).

 

Typical Applications:

Semi-production small yachts, train and truck body panels.