Grob G550T

The GROB G550T sits among GROB's mill-turn machining centers: an 800 x 1,020 x 970 mm universal machine whose B axis runs at up to 800 rpm, so the table can spin a part for turning as well as position it for milling. It shares travels and rapid traverse with the G550, 65/50/80 m/min in X/Y/Z, and differs from it in three places a buyer should weigh: table load, spindle choice and tool interface.

Table load is 750 kg without a pallet and 600 kg with one. The G550 is rated 800 kg without a pallet and 700 kg with one, so the turning table gives up capacity in both builds and more of it once a pallet is involved. Interference diameter is 900 mm over a 770 mm table. For turned parts, add the chuck or fixture to the part weight and compare the total with the load for the build being ordered.

Three spindle versions are listed, and all are on the torque side: HSK-A/T63 with 206 Nm at 16,000 rpm, HSK-A/T100 with 340 Nm at 10,000 rpm, and HSK-A/T100 with 261 Nm at 14,500 rpm. The lowest torque on offer is 206 Nm. Holders must suit the HSK-A/T63 or HSK-A/T100 interface chosen.

Chip-to-chip time is 3.0 s (t1, according to VDI 2852) and positioning accuracy 0.006 mm in X, Y and Z. The A axis swivels 230 degrees. Tools can be 465 mm long in the single disk-type magazine (HSK-A/T63); the double disk-type magazine takes 465/280/700 mm (bottom/top/over both disks). The machine weighs 24,800 kg and runs SIEMENS 840D sl or HEIDENHAIN TNC 640 with GROB4Pilot.