Grob G350

The GROB G350 is a 5-axis universal machining center with 600 mm of X, 855 mm of Y and 750 mm of Z travel, a 570 mm table and, as standard, a 12,000 rpm HSK-A63 spindle. GROB quotes a 720 mm interference diameter, so the part and its fixture may be wider than the table.

Spindle choice is where this model gets configured for the work. The standard unit gives 83 Nm at up to 12,000 rpm, and it is the spindle the 52 kW power figure belongs to. Four alternatives are listed, all HSK-A63: 206 Nm at 16,000 rpm, 47 Nm at 18,000 rpm, 47 Nm at 21,000 rpm and 63 Nm at 30,000 rpm. The 206 Nm version has roughly two and a half times the torque of the standard spindle and is the one to look at for steel. The 47 Nm and 63 Nm versions trade torque for speed and belong with small tools and finishing. There is no larger interface on this size.

Rapid traverse differs a good deal by axis: 70 m/min in X, 45 m/min in Y and 90 m/min in Z. Chip-to-chip time is 2.7 s (t1, according to VDI 2852). The A axis swivels through 230 degrees, the B axis turns 360 degrees, and positioning accuracy is 0.006 mm in X, Y and Z.

Load and tool length depend on the build. The table takes 400 kg without a pallet and 340 kg with one. The machine weighs 15,300 kg, or 17,500 kg with the pallet changer. Tools can be 365 mm long in the single disk-type magazine. In the double disk-type magazine the limit is 365 mm in the bottom disk, 180 mm in the top disk and 550 mm over both disks. The control is SIEMENS 840D sl or HEIDENHAIN TNC 640, with GROB4Pilot.