Mill-Turn Centers' B Axes Enable High-Precision Machining

Mori Seiki says its NT Series of integrated mill-turn centers combines the turning ability of a lathe and the cutting ability of a machining center. The machines employ both driven-at-the-center-of-gravity (DCG) technology and the box-in-box construction of the NH Series HMCs along with the turret and built-in milling motor of the NL Series CNC lathes. To reduce backlash and enable high speed rotation, the machines contain B axes that use direct-drive motors. Indexing specifications for the axis allow input by units of 0.0001 degrees, which is suitable for high-precision machining, the company says. Maximum spindle speed is 5,000 rpm, and maximum tool-spindle speed is 12,000 rpm. The machines' ATCs achieve tool-to-tool change times of 1 second and chip-to-chip times of 3.4 seconds. The lower turret is located symetrically in relation to the center of the spindle, forming a construction that resists heat, the company says. In addition, ballscrew and motor-jacket cooling can reduce innacuracies caused by heat fluctuations. The machines use the company’s Maps III control system, which is equipped with a collision-prevention function that monitors machine movements in real time. Nine models are available with various options.