Mitsui Seiki USA Inc.
The new horizontal machine has thicker structure and specially developed rib configuration to establish its rigidity Reportedly each axis boxway as well as the rotary axis mounting ball screw mounting points and spindle attachment surfaces are finished by hand to achieve precise parallelism squareness and straightness

New HMC Promises Precision, Power, Torque

April 25, 2013
Structure maximizes rigidity X, Y, and Z positioning and repeatability, +/- 0.001 mm

The new HU63EX horizontal machining center was engineered to increase the productivity of machine shops and metalworking operations by a combination of precision, power, and torque. That’s according to details supplied by the developer, Mitsui Seiki USA Inc. It detailed that the 17,000-kg (37,400 lb) machine has a footprint of 2,900 x 3,180 mm (116 x 127 in.), and achieves X, Y and Z axes travels of 900, 800, and 800 mm (36, 32, and 32 in.), respectively.

The structure of the machine maximizes its rigidity and accuracy during operation. The bed is a single casting supported at three points, which improves stabilization and minimizes the effect of foundation movements on the machining process.

A thicker structure and specially developed rib configuration establish the high rigidity.As explained by Mitsui Seiki, the mating surface of each axis boxway, as well as specific elements like the rotary axis mounting, ball screw mounting points and spindle attachment surfaces, are carefully finished by hand to achieve precise geometric characteristics, such as parallelism, squareness, and straightness. This ensures accurate performance over an extended period of time, the developer asserted.

Air cavities between the ways and the column mating surfaces are charged with low-pressure air, to reduce the load on the way surface and enable smoother movement, without compromising rigidity.Ball screws at the center of each guideway also stabilize machining movements.

Mitsui Seiki said the HMC achieves X, Y, and Z axis positioning and repeatability accuracy of +/- 0.001 mm (+/- 0.00004 in., or one micron), and B axis (rotating the 630-mm-sq. [25.2 in.] pallet) accuracy of +/- 2 sec., with repeatability +/- 1 second.

The designer also indicated that the focus on accuracy and rigidity in this model produces repeatable precision performance. In turn-boring operations on 10 consecutive workpieces the HU63EX achieved concentricity within three microns, Mitsui Seiki reported.

In addition to precision, the HU63EX offers substantial power and torque. The machine’s standard 50-taper, 6,000-rpm spindle delivers 18.5/15-kW (30 min./continuous, 24.7/20 hp) power with 601 nm (443 ft-lb) torque, delivered through a two-step gearbox. Optional spindles include a 6,000-rpm, 26kw/22 kW (34.8/29.4 hp) unit with 1,081 nm (797 ft-lb) torque; and a three-step gearbox, and a 12,000-rpm, 30-kW/25 kW (40/33.5 hp) version, with 420-nm (309 ft-lb) torque driven by an integral, built-in motor.

About the Author

Robert Brooks | Content Director

Robert Brooks has been a business-to-business reporter, writer, editor, and columnist for more than 20 years, specializing in the primary metal and basic manufacturing industries.