Okuma MA-4000H

The Okuma MA-4000H is a horizontal machining center on a 400 × 400 mm (15.7 × 15.7 in) pallet, with a 15,000 rpm spindle, 60 m/min (2,362 ipm) rapids and a tool magazine offered in eight sizes from 48 to 340 tools. Pallet load is 400 kg (882 lb).

Y travel is 650 mm (25.6 in) and Z travel is 685 mm (27.0 in); the machining volume row gives X as 22.05 in. The 400 kg pallet limit has to cover the tombstone, the vises or fixture plates and the parts together. On a pallet of this size a steel tombstone uses a good share of that allowance before any part is loaded, so the fixture material is worth deciding with the load figure in hand.

Okuma lists spindle power as 38/18.5 kW (51/25 hp). The two ratings are far apart. Sustained cuts should be planned around the 18.5 kW figure, while the 38 kW figure is what the spindle can call on for acceleration and short heavy cuts. The standard speed is 15,000 rpm, with 12,000 rpm and 20,000 rpm spindles shown as options. The table does not give the taper or a torque figure.

The magazine range is the unusual part of the table. 48 tools is standard, and the bracketed options are 64, 140, 180, 220, 260, 300 and 340. Capacity on that scale earns its keep when many part numbers stay set up at once and duplicate tools are loaded to cover wear over long unattended runs.

The MA-500HII is the next step in pallet size, at 500 × 500 mm (19.69 × 19.69 in), with a No. 50 spindle rated 30/22 kW (40/30 hp) and the same 60 m/min (2,362 ipm) rapids. It is the one to compare when the parts call for heavier tooling instead of higher spindle speed.