Citizen Miyano BNC-42

The Citizen Miyano BNC-42 is a single-spindle, fixed-headstock CNC bar lathe for bar stock up to 42 mm in diameter, with a 60 - 6,000 rpm spindle on a 7.5/5.5 kW motor (fifteen-minute/continuous rating) and an 8-station turret. It is not in Citizen's current lineup under that name; the listed table is the BNC-42C7 column of the BNC series page, so on a used machine check which generation is on the nameplate.

Workholding is flexible for a machine of this size. The spindle takes a 5-inch or 6-inch hollow power chuck, or collets to the HARDINGE S20, DIN173E, B&S #22D and JPN34 patterns, on a special flat type spindle nose. Collets suit bar work through the spindle; the hollow chuck covers slugs and larger short parts while still letting bar pass.

The turret is indexed by an AC servo motor and locked by a curvic coupling, at 0.2 sec per station. Square turning tools have 20 mm shanks and drill shanks are 25 mm or 32 mm in diameter. Up to 8 revolving tools can be fitted, running at 50 - 5,000 rpm on a 2.8/1.0 kW motor, but the table marks them as optional, so a machine without them turns and drills on centre only. The slides travel 135 mm in X and 235 mm in Z, with rapids of 20 m/min on X and 24 m/min on Z.

There is no sub-spindle in the table, so the cut-off face of each part is left for a second operation or a separate fixture. The machine is compact for a bar lathe: 2,272×1,270 mm of floor space, a height of 1,686 mm and a weight of 2,400 kg, with a Mitsubishi M80 control.