Sheet Molded Compound (SMC) is a polyester-based composite material, widely used by many industries especially automotive, as it offers high strength-to-weight ratio. But you must recognize that SMC repair is a subject unlike other materials.
Why Polyester Resin For SMC Repairs Will Not Do
Since SMC is manufactured with mold release agents in it, repair using standard polyester resin will be prevented. The resin is filled with these agents and they are present in the SMC part from top to bottom.SMC Repair (ad) Fresh mold release agents are revealed e.g. when sanding damaged areas to prepare for repair – with the result being a surface that polyester resins won’t bond properly to. It leads to minor repairs that are bound to fail over time13.
Recommended Repair Methods
In order to repair SMC properly it is necessary that the epoxy based resins or specialized adhesives be used for this. As compared to polyester resins, epoxy resins have better adhesion and can bond successfully with mold release agents. Also, anything less than complete sanding and cleaning of the surface will not provide adhesion as needed for a successful repair25.
Other materials and techniques
Two-part urethane adhesives, depending on the case can also produce similar results as well. These adhesives are designed to be compatible with SMC and can gap-fill or provide good strength. Repair36 must be applied in a RIGHT manner using special application techniques for it to endure.
In conclusion, it can be said that SMC is a versatile and strong material however the repair of an SMC component has to consider with great care which filler materials are used how these fillers should applied in order for them to serve their purpose.
