Tiny moulds for watches

The micro-plastic injection industry traditionally uses either WEDM (wire electric discharge machining) or LIGA technology to produce micromoulds. However, the 30 micro m diameter of the wire used in the WEDM technique and the cost and time factor of the LIGA technique are limiting factors for further miniaturisation of moulds.

Swiss microcomponent specialist, Mimotec, has now patented a process which, it claims, combines the thicknesses of the LIGA technique and the low costs of WEDM.

Since 1998, the company has injected over 50,000,000 units of components for the watchmaking, medical, robotics and IT sectors.

Products are produced using the Mimetal and MIMOTEC processes. The latter allows the patterning of detailed structures (1.5mm) using SU-8 (an epoxy-negative-tone resist) and electro-deposition of nickel to create blanks for injection molding or die manufacturing.Mimotec claims that with this method it is possible to miniaturise the size of the teeth in a conventional watch, and also that it is possible to use photoplastic parts as mechanical components.