Tham khảo tài liệu 'process selection - from design to manufacture part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 84 Selecting candidate processes Spray lay-up use of an air spray gun incorporating a cutter that chops continuous rovings to a controlled length before being blown into the mold simultaneously with the resin. Molds can be made of wood plaster concrete metal or glass fiber reinforced plastic. Cutting of composites can be performed using knives disc cutters lasers and water jets. Economic considerations Production rates low. Long curing cycle typically. Production rates increased using SMC materials. Lead times usually short depending on size and material used for the mold. Mold life approximately 1000 parts. Multiple molds incorporating heating elements should be used for higher production rates. Material utilization moderate. Scrap material cannot be recycled. Limited amount of automation possible. Economical for low production runs 10-1000. Can be used for one-offs. Tooling costs low. Equipment costs generally low. Direct labor costs high. Can be very labor intensive but not skilled. Finishing costs moderate. Some part trim is required. Typical applications Hulls for boats and dinghies Large containers Swimming pools and garden pond moldings Bath tubs Small cabins and buildings Machine covers Car body panels Sports equipment Wind turbine blades Prototypes and mock-ups Architectural work Design aspects High degree of shape complexity possible limited only by ability to produce mold. Produces only one finished surface. Fibers should be placed in the expected direction of loading if any. Random layering gives less strength. Avoid compressive stresses and buckling loads. Used for parts with a high surface area to thickness ratio. Molded-in inserts ribs holes lettering and bosses are possible. Draft angles are not required. Undercuts are possible with flexible molds. Minimum inside radius 6 mm. Minimum section mm. Maximum economic section 30 mm but can be unlimited. Sizes ranging m2 in area. Maximum size depends on ability to produce the mold and the .
