Wire-cut EDM micro-turning provides solution to small ambitions

Hirschmann was highlighting its new H80R.MAC 1,500 rpm rotary spindle for submerged use which supports wire-cut EDM micro-turning with the finest of surface finishes and has a runout of 0.005 mm - its previous lower speed model could not deliver such high-quality surface finishes. There are no forces involved in the wire-cut EDM turning process so the dimensions that can be achieved are remarkable. Examples include medical metering devices featuring a bore with small undercuts within. To produce this required a microscopic EDM electrode having three stepped diameter features that are 0.6 mm in diameter connected with a spindle of material of diameter of 0.050 mm. In another case, an EDM electrode for the production of an M1 tapped hole in hardened steel was produced. Another example involves a plunger for a micro-pump whose 1 mm diameter spherical end and ground stem connecting feature were wire-cut EDM turned. And another is a needle for a medical application whose spherical end had to be 0.3 mm in diameter at the end of a tapering diameter that started at 0.65 mm diameter. There is already one UK application of the technology, the production of micro ejector pins for small mouldings. In many cases the process can replace grinding and when the complete process including dresser manufacture, set-up and grinding is taken into account, EDM turning can be faster.