Components are becoming more and more complex and drawing tolerances ever tighter. The ability of live turret tooling in a CNC mill-turn centre to move in the Y axis, as well as in the X and Z, has therefore become increasingly important to facilitate high accuracy, one-hit machining.

If travel in only the latter two axes is provided, milling of flats, deburring, and the possibility of machining pockets and off-centre features in-cycle are either difficult or impossible.

The latest Miyano fixed-head lathe from Citizen Machinery UK to be equipped with a Y axis turret, in this case with all 12 tool stations driven, is the new BND-64SY for turning parts from bar up to 64mm diameter.

Joining a similar model that accepts bar up to 51mm diameter through the main spindle, the 4.75-tonne machine is a mid-range, multi-purpose, twin-spindle turning centre. A ribbed, monobloc bed slanted at 30deg carrying precision-scraped, square guideways provides high-rigidity, optimal thermal and mechanical stability and excellent vibration damping.

These characteristics result in high accuracy of mill-turned components and longer service life of the tools, which may be mounted flexibly in the turret using multi-tool holders at any turret position.

The robustness of machine construction allows turning as well as milling of tough alloys and metals in their hardened condition, even when taking intermittent cuts. Polygon turning and thread milling are both options in the Fanuc 0i-TD control, which is capable of simultaneous four-axis interpolation.

The specification of the Japanese-built machine includes turret travels in the X, Y and Z axes of 175 x 75 x 435mm, 530mm sub-spindle axis travel, up to 20m/min rapid feed rate, 2.2kW/20Nm/6,000rev/min driven tools, a 15/11kW main spindle and a sub-spindle rated at 5.5/3.7kW, both offering rotational speeds up to 5,000rev/min. A parts catcher and conveyor are supplied as standard, while the chip conveyor is optional.