Rapid investment casting: direct and indirect approaches via model maker II

Although investment casting (IC) provides an economical method for the mass production of metal parts with complex and intricate features, the relatively long lead times and high tooling costs involved in the manufacture of metal moulds for the fabrication of sacrificial IC wax patterns lead to cost justification problems for customised single casting, small and medium quantity production. The application of rapid prototyping (RP) technologies to fabricate complex sacrificial IC patterns can result in significant reduction in the costs and lead times associated with single part or small quantity production. Previously, the authors assessed the suitability of the fused deposition modelling process, in particular ABS models, for creating sacrificial IC patterns [1]. The current research looks into the feasibility of employing patterns fabricated by Model Maker II (MMII) as sacrificial IC patterns to produce metal castings rapidly. In addition, an indirect approach involving the utilisation of silicone rubber moulding with an MMII-fabricated master pattern to produce sacrificial IC wax patterns is investigated. The dimensional accuracies and surface qualities of the final metal castings generated from the RP-produced patterns are presented. Cost and lead time comparisons are also carried out and presented .