Okuma GP-GA-44FII

$230,000 - $320,000 Updated 2026-03-13

Key Specifications

X Travel

305 mm (12.01 in)

Z Travel

525 mm (20.67 in)

Rapid Traverse

max grinding diameter

400 mm (15.7 in)

distance between centers

350 / 650 / 1,000 / 1,500

grinding wheel size

510 x 75 mm (20.1 x 3.0 in)

Overview

The Okuma GP-GA-44FII is a large-capacity CNC cylindrical grinder from Okuma's GA-F series, stepping up to a 400 mm (15.7 in) maximum grinding diameter with 500 mm (19.7 in) between centers. This positions the GA-44FII for heavy-duty precision grinding of large-diameter components including pump shafts, large bearing housings, gear blanks, and heavy industrial parts that exceed the 340 mm capacity of the GA-34/36 models.

The grinding wheel is 510 x 75 mm (20.1 x 3.0 in) with a maximum peripheral speed of 45 m/s (8,858 sfm). The larger workpiece diameter capacity requires a more powerful wheel spindle motor to maintain material removal rates, and the GA-44FII delivers increased grinding power compared to the smaller GA-34FII. The wheel spindle uses hydrodynamic bearings for vibration-free operation critical to achieving fine surface finishes on large-diameter surfaces.

The X-axis (infeed) travel is 305 mm (12.01 in) with a minimum feed increment of 0.0001 mm (0.000004 in). The Z-axis (traverse) travel is 525 mm (20.67 in). Rapid traverse rates are 10 m/min (394 ipm) on X and 15 m/min (591 ipm) on Z. The headstock provides workpiece rotation from 10 to 350 RPM with an MT5 center and optional workpiece driving options for heavier components.

The FII generation OSP-P300G control provides automatic multi-step grinding cycles, gap elimination, in-process gauging integration, and programmable dressing sequences. The table swivels +/- 6 degrees for taper grinding. The larger X-axis travel accommodates the increased grinding diameter while maintaining the approach and clearance distances needed for safe operation.

Machine weight is approximately 7,000 kg (15,432 lb). Floor space runs approximately 4,000 x 2,600 mm (157 x 102 in). New pricing typically ranges from $230,000-$320,000. The GP-GA-44FII competes with Studer S41, Toyoda GL4Pi, and Danobat LG series for large-diameter precision cylindrical grinding.

Full Specifications

Parameter	Value
Max Grinding Diameter	400 mm (15.7 in)
Distance Between Centers	350 / 650 / 1,000 / 1,500
Grinding Wheel Size	510 x 75 mm (20.1 x 3.0 in)
Wheel Speed Max	45 m/s (8,858 sfm)
X-Axis Travel	305 mm (12.01 in)
Z-Axis Travel	525 mm (20.67 in)
Min Feed Increment	0.0001 mm (0.000004 in)
Rapid Traverse X	10 m/min (394 ipm)
Rapid Traverse Z	15 m/min (591 ipm)
Workhead Speed	10 - 350 RPM
Workhead Center	MT5
Swivel Angle	+/- 6°
Machine Weight	7,000 kg (15,432 lb)
Floor Space	4,000 x 2,600 mm (157 x 102 in)
CNC Control	Okuma OSP-P300G
Max Grinding Dia	Ø400
Grinding Wheel Odxid	Ø455x127
Max Grinding Wheel Width	75
Rapid Traverse Rate	16
Wheel Spindle Motor	7.5
Okuma Global Repair Center	Charlotte, North Carolina
Inches	Metric

Specifications sourced from okuma.com — verified 2026-03-28

Strengths & Limitations

Strengths

400 mm maximum grinding diameter handles large-diameter components like pump housings, gear blanks, and large bearing races that smaller grinders cannot accommodate
305 mm X-axis travel provides the extended infeed stroke needed for positioning on larger workpiece diameters while maintaining grinding clearance
0.0001 mm feed resolution ensures precision finishing capability is maintained even on the larger workpiece diameters where tolerance percentages are tighter
Hydrodynamic wheel spindle bearings maintain vibration-free operation critical for surface finish quality on large-diameter ground surfaces
FII generation control improvements reduce cycle time through faster gap elimination and more efficient multi-step grinding sequence execution
Increased wheel spindle power maintains material removal rates on larger-diameter workpieces where contact arc length increases

Limitations

500 mm between centers limits workpiece length; large-diameter long shafts require the GA-47FII with its 1,000 mm center distance
10-350 RPM headstock range is lower than the smaller GA models, reflecting the need for lower speeds on heavy, large-diameter workpieces
Single wheelhead configuration requires multiple plunge positions for multi-diameter grinding on complex parts
7,000 kg machine weight and 4,000 x 2,600 mm footprint require dedicated grinding area with appropriate foundation
No integrated angular or ID grinding heads; complex parts requiring multiple grinding operations need separate machines or setups

Best For

Heavy equipment manufacturers grinding large pump shafts, hydraulic cylinder components, and gear blanks exceeding 300 mm diameter Bearing manufacturers grinding large-diameter bearing races, housings, and roller components in the 300-400 mm range Aerospace manufacturers grinding large-diameter turbine disk ODs, spacer rings, and seal runner surfaces requiring precision cylindricity Power generation shops grinding large generator shafts, rotor components, and turbine bearing journals Mining and construction equipment manufacturers grinding large pin components, pivot shafts, and wear surfaces

Frequently Asked Questions

01 What does an Okuma GP-GA-44FII cost?

New pricing ranges from $230,000-$320,000 depending on options. The price reflects the larger-capacity X-axis, more powerful wheel spindle, and heavier construction compared to the GA-34FII. In-process gauging and workpiece driving systems are common options for large-diameter production grinding.

02 What's the practical difference between 340 mm and 400 mm grinding capacity?

The jump from 340 mm to 400 mm opens up a significant range of industrial components. Large pump shafts, heavy bearing housings, and gear blanks commonly fall in the 340-400 mm range. If your workpieces occasionally exceed 340 mm, the GA-44FII prevents having to outsource or use alternative methods. If they never exceed 340 mm, the GA-34FII saves money.

03 Can the GA-44FII handle heavy workpieces?

Yes. The MT5 headstock center and optional workpiece driving systems accommodate heavy parts. The machine's 7,000 kg mass provides stable grinding on heavy workpieces. For very heavy components, additional workpiece support may be needed. Consult Okuma for maximum workpiece weight specifications based on your specific configuration.

04 How does this compare to the GA-47FII?

Same 400 mm grinding diameter, but the GA-47FII offers 1,000 mm between centers vs the GA-44FII's 500 mm. Choose the GA-44FII for compact large-diameter parts and the GA-47FII for long shafts with large diameters. The GA-47FII costs more and requires more floor space.