1. The aim of this project is to understand the methodology of undertaking Composite Molding. It involves development of a composite using resins, hardeners and natural/artifical fibres. The advantage of these composites is flexibility in manipulating the shape of the final product and also the strength and toughness of the final product.
2. There are various methods for undertaking Molding using Composites. For the purpose of this exercise Hand Lay Up technique was undertaken.
Hand Lay Up
3. Hand lay-up is the simplest composites molding method, offering low cost tooling, simple processing, and a wide range of part sizes. Design changes are readily made.
4. In this method a non stick coat is applied on the mold surface, to ensure the resin applied as a part of the Mold making does not adhere to the surface of the cast being used. This can be achieved using a Gel coat or a non stick cling wrap onto the surface which is being used for undertaking the molding.
5. Post application of the non stick coat, the natural fibres/ fibre glass reinforcements are placed manually in the cast. On each layer of the fibre epoxy and hardener mixture which has been mixed thoroughly in the correct ratio as prescribed is applied using a brush/ paint roller. The use of a roller is recommended to thoroughly wetting the reinforcement and removing entrapped air. Subsequent layers of fiberglass reinforcement are added to build laminate thickness. In sandwich constructions low density core materials such as end-grain balsa, foam, and honeycomb, are commonly used to stiffen the laminate.
5. Post application of the non stick coat, the natural fibres/ fibre glass reinforcements are placed manually in the cast. On each layer of the fibre epoxy and hardener mixture which has been mixed thoroughly in the correct ratio as prescribed is applied using a brush/ paint roller. The use of a roller is recommended to thoroughly wetting the reinforcement and removing entrapped air. Subsequent layers of fiberglass reinforcement are added to build laminate thickness. In sandwich constructions low density core materials such as end-grain balsa, foam, and honeycomb, are commonly used to stiffen the laminate.
6. Post completion of the lay up the top of the mold is covered with a non stick surface and the uniform weight is placed on top of the cast to ensure trapped air is removed and the cast is compressed to ensure good adherence between the fibres and the applied resin.
7. For the purpose of this exercise a bowl was considered as a cast. In the cast a non stick layup of cling wrap was applied. On the non stick wrap, natural fibres were layed up and a resin and hardener mixture in 2:1 ratio was applied using a spatulla.
8. In this exercise the fibres were placed in 4 layers and each time the resin mixture was applied using a spatulla. Post application of the resin on sufficient number of layers a non stick layer of cling wrap was placed again on the mold and a weight was placed on top of the material.
9. The mold is left for curing at room temperature for a period of 24 hours. Post curing the weight was removed and the mold generated was seperated from the cast. The structure was smoothened and the edges of the structure were trimmed to arrive at a final product.
