Vacuum casting allows the production of small batches of high quality moldings in a range of polyurethane resins that replicate the performance of engineering plastics without the high costs of hard tooling associated with injection molding.
The process starts with making a mold by encapsulating a master model in two-part liquid silicone rubber. A vacuum is then applied to remove any trapped air, then it is cured in an oven. Master models can come from a number of 3D printing technologies including stereolithography.
Once the silicone is cured, the mold is cut open to form a split line, the master model is removed which leaves a mold cavity perfectly replicating the master model.
To make a part, the mold segments are put back together, secured, pre‑heated and placed in the vacuum casting system chamber. Two or three part resin is weighed, pigment added if required and the resin parts are placed in the automatic mixer of the vacuum casting system.
At this point, the vacuum casting system takes over the process to mix the resin components and vacuum cast the model. Once this is complete the casting is cured at 70 °C. After curing, the mould segments can be separated and the part removed.
All that remains is for the part to be trimmed and finished as required.
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