The feasibility of silicone rubber as an injection mould tooling process using rapid prototyped patterns

The use of silicone rubber tooling has become established with Rapid Prototyping (RP) part to obtain multiple plastic copies of the part. However, these parts are not usually in the desired end material and are typically polyurethanes. Furthermore, the cycle times in part production are relatively long (hours), and thus the aim of obtaining multiple rapid copies is not fulfilled. Additionally, standard vacuum casting equipment costs are high. The research work has applied silicone moulds to injection moulding and this is the focus of this paper. The silicone is modified to make it stronger and to improve heat conductance so that it may be used to inject plastic into. Succesful results have been obtained using such tools and a number of parts in low density polyethylene (LDPE), 30% glass filled polypropylene (PP) and polyamide (PA) have been produced. The approach requires low cost equipment, and tools can be easily produced from RP masters, at low cost. In this study the DTM Selective Laser Sintering (SLS) Process has been used for masters.