LIM and LSR materials thin-wall vacuum cast

A technology exists that allows the successful vacuum casting of thin walled parts from highly viscous, thick or thixothropic LIM and LSR materials.

A technology exists which allows the successful vacuum casting of thin walled parts from highly viscous, thick or thixothropic LIM and LSR materials.

This new technology, available from MCP Tooling Technologies, eliminates the need for the production of costly steel tooling to injection mould prototypes in production materials of flexible parts such as seals and gaskets, insulators, face masks, hoses and medical parts.

(Vacuum casting of LIM and LSR has been achievable in the past, but normally using only low viscosity types which are less successful for the production of thin wall sections.) The technology is an adaptation of MCP's vacuum casting process and has been built into a new MCP branded system known as VarioVac.

Whereas in the conventional vaccum casting process, both mixing and filling of the mould are undertaken at the same vacuum levels, the VarioVac machine incorporates two totally separate vacuum chambers.

Varying levels of vacuum can be applied to each chamber via the PLC controller.

The material can therefore be mixed by the robot under a low vacuum in the upper chamber and then effectively pulled by a higher vacuum into the mould in the lower chamber.

Mould fill is therefore highly efficient even when thick materials are being cast into complex, thin walled sections.

Normally, LIM and LSR prototypes are produced using injection moulding and require highly polished steel moulds heated to at least 130 - 200degC.(The heated mould accelerates the catalytic reaction of the 2 component silicone rubber and the polished mould stops any adhesion.) Using low cost silicone tooling and the new VarioVac system, MCP estimates that around 97% of costs and time can be saved when compared to the production of the same prototype parts using the injection moulding process.

The characteristics and properties of parts produced using the VarioVac process include high temperature resistance (over 300degC), anti-adhesion, non-irritant, bio-compatible, non-hygroscopic and oil resistance.

MCP explains that it anticipates its new technology will be largely used for the production of prototype parts, but it is equally suitable for short production runs.

A silicone tool can be quickly produced from a rapid prototyping model and is then cured overnight.

After casting the part in the VarioVac machine it will be ready to demould in an hour - the whole process could even be achieved in around 12 hours.

Parts can be produced in any colour and in varying Shore hardness.

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