Makino EDBV8

The Makino EDBV8 is an EDM hole-drilling machine built for the cooling holes of turbine blades and vanes, with 800 x 600 mm (31.5 x 23.6 in) of X and Y travel, an integral two-axis rotary table and a tool capacity of 24. Makino describes it as an expansion of the EDBV3, and the difference is reach: the EDBV3 has 370 mm (14.6 in) of X and 270 mm (10.6 in) of Y over the same 500 mm (19.7 in) Z.

The Z row reads 500 mm (19.7 in) with 750 mm (29.5 in) in brackets, and the table does not say what the second figure belongs to, so ask which Z the quoted machine carries. The rotary table turns 360° on A and swings -110/+30° on B, which lets one setup reach several faces and locations of a part. Its load is the figure to watch: 50 kg (110 lb) as standard and 150 kg (330 lb) with the option. Rapid traverse is 5 m/min (197 in/min).

All machining is done fully submerged, with water as the dielectric. The water reservoir sits in the base casting, and a chiller, water filtration and de-ionization are provided to keep the water in condition. Working submerged also removes the splash guards a manual setup would need and the slip hazard of over-spray. For film-cooling holes and diffusers, the break-through detection system recognises electrode break-through within 1 second or 0.040” (1.0mm) of depth, which is how the machine avoids internal back-striking.

The electrode and die guide are pre-assembled as one unit, so a single exchange performs both ATC and AGC (automatic guide change), and Makino gives the exchange as within 45 seconds. A Middle Guide system keeps long electrodes from bending and vibrating. Loading is through a 3-sided programmable rise-and-fall work tank, listed at 1,400 x 1050 mm (55.1 in x 41.3 in). The Hyper-i control runs on a 24” class high-definition touch screen with a Windows 7 operating system.