Doosan’s NHM5000 is a new, horizontal machining centre designed to achieve tight tolerances in hard-to-cut materials, while machining parts as large as 33.5 in. x 43.3 in. (851 mm x 1,100 mm).
At its heart is a massive, one-piece casting that provides a rigid base for the table and column. The bed consists of fine-grain Meehanite to dampen vibration and dissipate heat. Ribs are strategically located to improve rigidity. The integral box ways are induction hardened, precision ground, and coated with a low-friction fluoroplastic resin for longer life, maximum rigidity, and greater precision.
Powering the spindle is a 25 hp, two-geared motor that generates speeds up to 6,000 rpm, and produces 704 ft-lb of low-end torque. A refrigerated spindle cooling system maintains a constant spindle temperature for high accuracy, regardless of ambient temperature or cutting conditions. Coolant circulates through jackets in the spindle head as well as through the gearbox.
Feeding the spindle is a servo-driven ATC that accommodates 60 tools (up to 376 optional) 50-taper, with maximum diameters of 12.6 in. (320 mm) and lengths of 20.9 in. (531 mm). The Big Plus dual contact system allows contact between the machine spindle face and the tool holder flange face, and at the same time between the machine spindle taper and the tool holder taper shank. The result is higher rigidity, better ATC repeatability, superior surface finish, and extended tool life, claims Doosan. Tool-to-tool time is a quick 2.0 seconds.
The NHM5000’s APC is equipped with a rotary type, high speed servo motor with reducing gear. This enables fast, 9.6 second pallet changes, with a high degree of reliability. Its table measures 19.7 in. x 19.7 in. (500 mm x 500 mm), supports a load of 1,764 lb (800 kg), and indexes to 4 x 90°.
Additional features include a ball-screw nut cooling system as a standard, and ball-screw shaft cooling as an option. Coolant is also used to flush chips from the spindle and slide covers. The coolant tank’s capacity is 218 gallons. An oil skimmer is included to remove tramp oils, and to reduce the cost of coolant disposal.