Vacuum Casting is a process used to produce multiple accurate components from a single master model in materials that closely mimic many production plastics. A liquid Silicone rubber is used to encapsulate the master (normally an SLA model) and then, once cured, cut open to create the mould tool. The mould is then placed under vacuum, where a 2-component Polyurethane resin is used to fill the cavity and create the casting.
The silicone tools have a limited production capacity with the number of parts we would expect a single tool to produce dependant on a number of factors:
- The geometry of the part (long draws and undercuts/clips can accelerate wear)
- The PU resin required (filled or clear parts can decrease the quantity)
- The Finish required on the parts (gloss finishes can accelerate wear and high quality finishes my reduce castings achievable)
As a guide we would expect around 20x castings per tool but this can increase to 25x-30x (low finish or softer Shore A material) or decrease to 10x parts (filled resins or thick section parts). The creation of multi-cavity moulds, where possible, will greatly improve the number of castings we can achieve as well as cost effectiveness and we will advise where this is feasible.