Okuma GP-47N
Key Specifications
X Travel
Z Travel
max grinding diameter
distance between centers
grinding wheel size
wheel speed max
Overview
The Okuma GP-47N is a CNC universal cylindrical grinder from Okuma's N series, featuring a swivel wheelhead that enables both OD cylindrical grinding and angular approach grinding in a single machine. The 47 designation indicates a 400 mm (15.7 in) maximum grinding diameter with 500 mm (19.7 in) between centers, matching the GA-44FII's capacity but adding the angular wheelhead capability that makes it a universal grinder rather than a plain cylindrical grinder.
The swivel wheelhead rotates to position the grinding wheel at angles for shoulder grinding, taper grinding, and angular plunge operations. This eliminates the need for table swivel in many angular grinding applications and provides more precise angle control for compound grinding profiles. The grinding wheel is 455 x 50 mm (17.9 x 2.0 in) with a maximum peripheral speed of 45 m/s (8,858 sfm). The wheel spindle uses hydrodynamic bearings for vibration-free operation.
The X-axis (infeed) travel is 275 mm (10.83 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 400 RPM with an MT5 center.
The N series OSP-P300G control includes automatic angular positioning of the wheelhead, allowing programmed angle changes between grinding operations on multi-feature workpieces. This automation reduces setup time on complex parts that require both cylindrical and angular grinding. Gap elimination and in-process gauging are standard features. The machine can be equipped with an ID grinding spindle attachment for combined OD/ID/face grinding on components like bearing rings.
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 $250,000-$350,000. The GP-47N competes with Studer S31/S33 universal models, Kellenberger Vita, and Junker Jumat for universal cylindrical grinding applications.
Full Specifications
| Parameter | Value |
|---|---|
| Max Grinding Diameter | 400 mm (15.7 in) |
| Distance Between Centers | 2,150, 2,650, or 3,150 |
| Grinding Wheel Size | 455 x 50 mm (17.9 x 2.0 in) |
| Wheel Speed Max | 45 m/s (8,858 sfm) |
| Wheelhead Swivel | Programmable angular positioning |
| X-Axis Travel | 275 mm (10.83 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 - 400 RPM |
| Workhead Center | MT5 |
| Id Grinding Spindle | Optional attachment |
| 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 | Ø760 × Ø304.8 |
| Max Grinding Wheel Width | 130 |
| Rapid Traversex | 12 |
| Rapid Traversez | 10 |
| Wheel Spindle Motor | 15 |
| Okuma Global Repair Center | Charlotte, North Carolina |
| Inches | Metric |
Specifications sourced from okuma.com — verified 2026-03-28
Strengths & Limitations
Strengths
- Swivel wheelhead with programmable angular positioning enables OD, shoulder, and angular plunge grinding in a single setup without table swivel
- Universal capability combines cylindrical, angular, and optional ID grinding on one machine, reducing the number of grinders needed in the department
- Automatic wheelhead angle changes between operations reduce setup time on multi-feature parts requiring both cylindrical and shoulder grinding
- 400 mm grinding diameter handles medium to large components with the same capacity as the dedicated GA-44FII cylindrical grinder
- 0.0001 mm infeed resolution maintains precision grinding capability across all angular positions of the wheelhead
- Optional ID grinding spindle attachment converts the machine to a full OD/ID/face grinding platform for bearing ring and similar applications
Limitations
- 455 x 50 mm wheel is narrower than the GA-F series' 75 mm wheel, reducing material removal rate per pass for pure OD plunge grinding
- Swivel wheelhead adds mechanical complexity and potential for angular positioning drift compared to fixed-head cylindrical grinders
- 500 mm between centers limits workpiece length; shops needing universal grinding on longer shafts should consider the GP-57N
- Price premium of $20,000-$30,000 over equivalent GA-F models reflects the swivel wheelhead mechanism
- ID grinding attachment adds cost and requires additional spindle maintenance; dedicated ID grinders like the GI series are more capable for production ID work
Best For
Frequently Asked Questions
01
New pricing ranges from $250,000-$350,000 depending on the wheelhead configuration, ID grinding attachment, in-process gauging, and automation options. The universal capability commands a premium over the equivalent GA-44FII plain cylindrical grinder.
02
A swivel wheelhead positions the grinding wheel at the desired angle while the table stays straight, allowing the workpiece to remain fixed between centers. Table swivel moves the entire workpiece, which can cause alignment issues on long parts. The wheelhead swivel is also faster to reposition and can be programmed for automatic angle changes between operations.
03
The GP-47N is ideal for shops grinding lower volumes of parts that need multiple grinding operations. For high-volume production where OD and ID grinding each need dedicated machines running continuously, separate optimized grinders provide faster cycle times. The GP-47N shines in job shop and mixed-production environments.
04
Both are universal cylindrical grinders with swivel wheelheads. The Studer S33 offers a wider range of wheelhead configurations and turret options. The Okuma provides competitive pricing and OSP control integration. The Studer has a stronger dedicated grinding heritage, while the Okuma benefits from the broader Okuma service network and machine tool ecosystem.
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