Director Ambekar E. Eknath, Ph. D Head, APED J.K. Jena, Ph. D ...

Limitations
. This technique is labour intensive and quality of the product depends
largely on one finished surface and is unsuitable if finish is required on
both surfaces.
r For mass productions, normally it cannot compete with press molding.
Thickness cannot be controlled with any degree of accuracy
It is difficult to obtain uniform glass to resin ratio
GRPl FRP Making
Stepl: Design of Mould
Mould is the prime requirement for making any FRP product. A suitable
mould must be made before any molding process is undertaken. This is one
of the most important steps, since it affects the quality of the molding. When
wide ranges of possible molding processes are available, many different
types of moulds are required. This can be made from wide varieties of
materials including wood, plaster of paris, concrete, sheet metal, epoxide,
polyester resins, non-ferrous metals and steel or a combination of these
factors, which affect choice of mould materials, include the number and size
of the moldings to be produced, the type and finish required and the molding
process. While designing the mould, several parameters like material
selection, mould thickness, mould trim line size, mould taper, etc are to be
considered.
Step -2: Construction of Mould
Open mould processes of FRP fabrication make use of only the male or
female half of the mould. Since pressure is not applied in hand lay-up or
spray-up methods, the moulds need not be as strong as the moulds used in
compression molding. Also, when heating is not required metallic moulds are
not essential. Wooden mould requires finishing work on moulds after every
cycle of molding. FRP moulds are ideal for intricate shapes. When heating or
pressing is required the metallic mould has to be coated with wax and
releasing agent. For trimming some allowances may be allowed, which is
slightly larger than the product dimensions.
Step - 3: Seal the Mould
The mould must be sealed to keep the resin from sticking on to it. Sealers
also tend to make the mould surface smoother. Mould sealed with polyester
resin is thoroughly dried. The plastic resin produces the best sealer finish. It
buffed to give a higher polish on the molded laminate.