HMC Designed For Big Parts

Doosan’s HM1250 HMC machines parts measuring 78.8" in diameter and 67.9" tall. The machine combines a high-torque spindle drive with powerful axis drives for a range of cutting applications. The three-speed spindle is driven by a 50-hp motor at speeds ranging to 6,000 rpm, and it generates 2,718 foot-pounds of low-end torque.

Tools are secured with the Big Plus system where dual contact exists between the machine spindle face and the toolholder flange face, as well as by the machine spindle taper and toolholder taper shank. According to the company, this results in high rigidity and longer tool life. The Big Plus system accommodates BT, DIN and CAT 50 flange tooling.

A 60-station, side-entry ATC is standard. 90- and 120-station, chain-driven ATCs and a 196-station, matrix-type ATC are optional. All are fixed-address designs for tools ranging to 55 lbs and 25.5" long × 5.1" in diameter (11.8" in diameter when adjacent ports are empty). The machine also features a tool-to-tool change time of 7.5 sec., and tools in the magazine can be changed during operation. A magazine servomotor ensures smoother movement and quiet operation, the company says.

To dissipate heat and damp vibration, the HMC features fine-grain Meehanite castings. Integral box ways along all axes ensure rigidity and accuracy. The guideways are induction hardened and precision ground. Fluoroplastic resin is bonded to the mating surfaces and then hand-scraped for fit. The fluororplastic resin combines with forced way lubrication to provide a low-friction coefficient for repeatability and a 945-ipm rapid traverse. Large-diameter ballscrews are preloaded on both ends for precise positioning.