GROB G520
Key Specifications
X Travel
Y Travel
Z Travel
Max Spindle
Spindle Taper
Tool Capacity
Overview
The GROB G520 is the mid-range workhorse in Grob's universal 5-axis machining center lineup, slotting between the G350 and the large-format G550. Like all Grob universal machines, the G520 features a horizontal spindle orientation and Grob's distinctive tunnel design, but with significantly larger travels and workpiece capacity than the G350. X/Y/Z travels of 800 x 1,020 x 975 mm (31.5 x 40.2 x 38.4 in) provide the work envelope to handle medium-to-large aerospace structural parts, die/mold components, and automotive production parts that exceed the G350's capacity.
The standard spindle runs at 16,000 RPM with an HSK-A63 taper, delivering 39 kW (52 hp) of power — identical to the G350 spindle but housed in a larger, more rigid machine structure. High-speed spindle options up to 21,000 RPM are available for aluminum-intensive applications. The A-axis provides 230 degrees of swivel while the B-axis rotates 360 degrees continuously, matching the G350's rotary axis capability but with a 750 mm (29.5 in) diameter table that accepts workpieces up to 700 kg (1,543 lb).
Rapid traverse rates of 60/45/75 m/min (X/Y/Z) are slightly slower than the G350's rates due to the larger moving masses, but still among the fastest in this size class. The G520's column construction is wider and deeper than the G350, providing increased static and dynamic rigidity for heavier cutting operations. This is particularly noticeable during aggressive roughing in titanium and steel where the G520's added mass dampens vibration more effectively.
The G520 is available with pallet changer options, linear pallet storage, and Grob's automation concepts for flexible manufacturing cells. The machine runs on Siemens SINUMERIK 840D sl control. New G520 machines price between $550,000 and $750,000 depending on configuration. Used units from 2016-2022 trade in the $250,000-$450,000 range. The G520 competes directly with the Hermle C 42, DMG Mori DMU 80 P duoBLOCK, and Mazak Variaxis i-700.
Full Specifications
| Parameter | Value |
|---|---|
| X-Axis Travel | 800 mm (31.5 in) |
| Y-Axis Travel | 1,020 mm (40.2 in) |
| Z-Axis Travel | 975 mm (38.4 in) |
| Max Spindle Speed | 16,000 RPM standard (up to 21,000 RPM optional) |
| Spindle Taper | HSK-A63 |
| Spindle Motor Power | 39 kW (52 hp) |
| A Axis Range | 230° swivel |
| B Axis Range | 360° continuous |
| Rapid Traverse X | 60 m/min (2,362 ipm) |
| Rapid Traverse Y | 45 m/min (1,772 ipm) |
| Rapid Traverse Z | 75 m/min (2,953 ipm) |
| Table Diameter | 750 mm (29.5 in) |
| Max Workpiece Weight | 700 kg (1,543 lb) |
| Tool Capacity | 60 tools standard (up to 365 optional) |
| Machine Weight | 19,500 kg (42,990 lb) |
| CNC Control | Siemens SINUMERIK 840D sl |
| Positioning Accuracy | 0.006 mm (0.00024 in) |
Specifications sourced from grobgroup.com — verified 2026-03-28
Strengths & Limitations
Strengths
- 800 x 1,020 x 975 mm travels provide 35-40% more work envelope than the G350 while maintaining the same horizontal spindle and tunnel design advantages
- 700 kg workpiece capacity handles medium-weight steel and titanium components that exceed the G350's 400 kg limit, broadening the range of parts that fit the machine
- Horizontal spindle orientation with gravity-assisted chip evacuation eliminates chip re-cutting, critical for high-volume aluminum and steel production with heavy chip loads
- Up to 365-tool magazine option supports complex multi-operation parts and extended unattended production runs without operator intervention for tool management
- Tunnel design minimizes the guide-to-TCP distance for exceptional dynamic stiffness, and the G520's wider column provides even better rigidity than the G350 for heavy cuts
- Grob's automotive production heritage ensures the G520 is engineered for continuous 24/7 duty cycles with thermal stability features built into the base platform
Limitations
- At 19,500 kg the G520 requires significant foundation preparation and rigging capacity, increasing installation costs compared to lighter vertical 5-axis platforms
- Siemens-only control limits shops standardized on Fanuc or Heidenhain, requiring different post-processors and potentially operator retraining
- $550,000-$750,000 new price is 30-40% higher than many competing 5-axis machines in this travel range, though the production-grade build quality justifies the premium
- Grob's dealer and service network in North America is smaller than Mazak, DMG Mori, or Okuma, which may impact service response times in some regions
Best For
Frequently Asked Questions
01
New GROB G520 machines start around $550,000 for a base configuration. Adding pallet changers, expanded tool magazines (up to 365 tools), high-speed spindle options, through-spindle coolant, probing, and pallet automation can push the price to $700,000-$750,000 or higher. Used G520 units from 2016-2022 trade between $250,000 and $450,000 depending on configuration, hours, and condition.
02
The G520 sits between the G350 (600 x 855 x 750 mm travels, 400 kg workpiece) and G550 (1,000 x 1,300 x 1,175 mm travels, 1,000 kg workpiece) in Grob's lineup. All three share the horizontal spindle tunnel design, same spindle platform, and Siemens control. The G520 is the optimal choice when G350 capacity is insufficient but G550 size and cost are excessive. The G520's 700 kg workpiece capacity covers most medium-format aerospace and automotive applications.
03
The horizontal spindle lets gravity pull chips away from the cutting zone naturally, preventing chip re-cutting that damages surfaces and tools. This is especially important during heavy roughing where large chip volumes must exit the cut efficiently. The horizontal orientation also provides a wider collision-free working envelope within the tunnel structure, allowing larger workpieces to be rotated through the A and B axes without interference.
04
Grob offers several automation levels for the G520: a standard 2-pallet changer for operator-side loading while the machine cuts, linear pallet storage systems for multi-pallet unattended production, and integration with robotic loading cells. The 365-tool magazine option is critical for automated production, as it eliminates tool-change interruptions across multiple part numbers. Grob also offers their own automation systems designed specifically for integration with the G-series machines.
05
Yes, the G520 is well-suited for titanium machining. The 39 kW spindle provides adequate power for the moderate speeds and feeds required by titanium, while the machine's mass and tunnel design deliver the dynamic stiffness needed to suppress vibration during interrupted cuts. The horizontal spindle ensures titanium chips clear the cutting zone reliably. Many aerospace users run Ti-6Al-4V on the G520 for structural brackets, fittings, and engine components.
06
Yes, Grob offers the G520T mill-turn variant that adds workpiece turning capability to the standard 5-axis milling platform. The mill-turn option enables OD and ID turning, facing, and threading operations, eliminating secondary operations on a lathe for parts requiring both milling and turning features. The G520T adds approximately $60,000-$90,000 to the base price and is popular in aerospace applications where complex parts benefit from done-in-one machining.
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