Okuma GP-GA15W

$150,000 - $220,000 Updated 2026-03-13

Key Specifications

X Travel

215 mm (8.46 in)

Z Travel

525 mm (20.67 in)

Rapid Traverse

max grinding diameter

150 mm (5.9 in)

distance between centers

250

grinding wheel size

405 x 50 mm (15.9 x 2.0 in)

Overview

The Okuma GP-GA15W is a compact CNC cylindrical grinder from Okuma's GA-W series, designed for precision OD and face grinding of small to medium workpieces. The W suffix indicates the wider wheelhead variant within the GA series. With a maximum grinding diameter of 150 mm (5.9 in) and a distance between centers of 500 mm (19.7 in), this machine targets small-shaft, pin, and precision component grinding applications common in automotive, medical, and general precision manufacturing.

The grinding wheel is 405 x 50 mm (15.9 x 2.0 in) with a maximum peripheral speed of 45 m/s (8,858 sfm) for conventional abrasives, and the machine can accommodate CBN and superabrasive wheels for higher-speed applications. The wheel spindle runs in high-precision hydrodynamic bearings for vibration-free grinding, which directly translates to surface finish quality. The table traverse is driven by a precision ball screw with linear glass scales for closed-loop positioning.

The X-axis (infeed) travel is 215 mm (8.46 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 500 RPM with a standard MT4 center.

The machine runs on Okuma's OSP-P300G grinding control, which provides automatic wheel dressing cycles, in-process gauging integration, and multi-step grinding sequences. Gap elimination sensing reduces air grinding time by detecting when the wheel first contacts the workpiece and automatically switching from rapid to grinding feed. Automatic wheel balancing is available as an option.

Machine weight is approximately 4,500 kg (9,921 lb). Floor space runs approximately 3,200 x 2,200 mm (126 x 87 in). New pricing typically ranges from $150,000-$220,000 depending on options. The GP-GA15W competes with grinders from Studer, Kellenberger, and Toyoda in the small-diameter precision cylindrical grinding segment.

Full Specifications

Parameter	Value
Max Grinding Diameter	150 mm (5.9 in)
Distance Between Centers	250
Grinding Wheel Size	405 x 50 mm (15.9 x 2.0 in)
Wheel Speed Max	45 m/s (8,858 sfm)
X-Axis Travel	215 mm (8.46 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 - 500 RPM
Workhead Center	MT4
Swivel Angle	+/- 6°
Machine Weight	4,500 kg (9,921 lb)
Floor Space	3,200 x 2,200 mm (126 x 87 in)
CNC Control	Okuma OSP-P300G
Max Grinding Dia	Ø150
Grinding Wheel Odxid	Ø510 × Ø203.2
Max Grinding Wheel Width	75
Rapid Traverse Rate	30
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

0.0001 mm minimum feed increment enables the ultra-fine infeed control needed for precision grinding to sub-micron tolerances on small-diameter workpieces
Hydrodynamic wheel spindle bearings provide vibration-free operation, directly contributing to surface finishes of Ra 0.1 or better on ground surfaces
Gap elimination sensing reduces air grinding time by automatically detecting wheel-to-workpiece contact, improving cycle times on repetitive production work
OSP-P300G control provides automatic multi-step grinding sequences including rough, semi-finish, finish, and spark-out passes without operator intervention
Compact footprint of 3,200 x 2,200 mm fits precision grinding capability into smaller shop spaces
Linear glass scales on both axes provide closed-loop positioning accuracy independent of ball screw thermal expansion

Limitations

150 mm maximum grinding diameter limits the machine to small-diameter workpieces; shops grinding larger shafts need the GA25W or larger
500 mm between centers restricts maximum workpiece length; longer shafts and spindles require larger-capacity grinders
OSP-P300G is Okuma-proprietary, so operators trained on Fanuc or Siemens grinding controls will need retraining
45 m/s maximum wheel speed is standard for conventional abrasives but may limit productivity with newer high-speed CBN wheel technology
Single wheelhead configuration means angular plunge and face grinding require table swivel rather than a dedicated angle head

Best For

Automotive manufacturers grinding small precision shafts, pins, valve stems, and bearing journals to tight OD tolerances Medical device manufacturers precision grinding surgical instrument components, implant pins, and orthopedic device shafts Precision job shops producing small batches of ground components where the OSP control's automatic cycle programming reduces setup time Bearing manufacturers grinding inner and outer race ODs on small to medium bearings Hydraulic component manufacturers grinding spool valves, piston rods, and precision cylindrical parts

Frequently Asked Questions

01 What does an Okuma GP-GA15W cost?

New pricing ranges from $150,000-$220,000 depending on options like in-process gauging, automatic wheel balancing, and workpiece loading automation. This positions it competitively against European grinders from Studer and Kellenberger, which typically cost more for equivalent capability.

02 What surface finish can the GP-GA15W achieve?

With proper wheel selection, dressing, and grinding parameters, the GP-GA15W can achieve surface finishes of Ra 0.1 micrometers or better. The hydrodynamic wheel spindle bearings and 0.0001 mm feed resolution are the key enablers. CBN wheels can produce even finer finishes with appropriate process development.

03 How does this compare to a Studer S33?

Both are precision CNC cylindrical grinders in a similar size class. The Studer S33 offers a broader range of wheelhead configurations and typically achieves slightly better roundness specifications. The Okuma counters with competitive pricing and the integrated OSP control ecosystem for shops already running Okuma equipment. Studer has a stronger reputation specifically in grinding, while Okuma brings broader machine tool experience.

04 Can the GP-GA15W use CBN wheels?

Yes. The machine can accommodate CBN and superabrasive wheels within the wheel size and speed specifications. CBN grinding typically requires through-coolant and may benefit from the optional high-speed wheel spindle. CBN provides significantly longer wheel life and better surface finish on hardened steels, making it cost-effective for production grinding despite the higher wheel cost.