Okuma GP-47N
Image: d30jruhmdicmo0.cloudfront.net, Okuma
Key Specifications
max grinding diameter
distance between centers
grinding wheel size
rapid traverse x
rapid traverse z
workhead speed
How much does the Okuma GP-47N cost?
Estimated price range
Our best estimate for a cnc grinding machine in this class — not a quote from Okuma. Configuration moves it a long way.
Overview
The Okuma GP-47N is a CNC cylindrical grinder for long shafts: a maximum grinding diameter of 400 mm (15.75 in) on a bed offered with 2,150, 2,650, or 3,150 mm (84.65, 104.33, or 124.02 in) between centers. It is the smallest-swing member of a three-size family that shares one bed range, one wheel and one wheel motor.
That shared hardware is a wheel listed at 760 × 304.8 mm (30 × 12 in) with a 130 mm (5.12 in) wheel width, driven by a 15 kW (20 hp) wheel spindle motor. On the GP-47N the motor has the least work diameter to deal with, so of the three sizes this is the one where wheel and motor are most generously matched to the part. A 130 mm wheel face also means journals narrower than that can be plunge ground in one infeed instead of traversed.
The workhead runs at 10 - 400 RPM and its center is MT5. The low end of that range is what matters on a machine this long. A heavy shaft near 400 mm in diameter needs slow rotation to keep its surface speed in check, while the top end suits the slimmer sections of the same part. Rapid traverse is 12 m/min (472 ipm) in X and 10 m/min (394 ipm) in Z.
Choosing within the family is mostly a question of swing. The GP-57N takes 550 mm (21.65 in) and the GP-67N 650 mm (25.59 in) over the same three center distances. If the parts are 400 mm or under but short, the GP-GA-47FII carries the same 760 × 304.8 mm wheel size on center distances from 350 to 1,500 mm (13.78 to 59.05 in), which leaves the GP-47N for work that will not fit in 1,500 mm.
Full Specifications
| Parameter | Value |
|---|---|
| Max Grinding Diameter | 400 mm (15.75 in) |
| Distance Between Centers | 2,150, 2,650, or 3,150 mm (84.65, 104.33, or 124.02 in) |
| Grinding Wheel Size | 760 × 304.8 mm (30 × 12 in) |
| Rapid Traverse X | 12 m/min (472 ipm) |
| Rapid Traverse Z | 10 m/min (394 ipm) |
| Workhead Speed | 10 - 400 RPM |
| Workhead Center | MT5 |
| Rapid Traversex | 12 |
| Rapid Traversez | 10 |
| Wheel Spindle Motor | 15 kW (20 hp) |
| Grinding Wheel Width | 130 mm (5.12 in) |
Specifications sourced from okuma.com — verified 2026-10-03
Strengths & Limitations
Strengths
- Three bed lengths, 2,150, 2,650, or 3,150 mm (84.65, 104.33, or 124.02 in) between centers, on a 400 mm (15.75 in) grinding diameter
- 760 × 304.8 mm (30 × 12 in) wheel with a 130 mm (5.12 in) width, so journals up to that width can be plunge ground without traversing
- Workhead speed range of 10 - 400 RPM, with a slow end suited to heavy, large-diameter shafts
- 15 kW (20 hp) wheel spindle motor, the same rating the GP-57N and GP-67N apply to larger work
- Rapid traverse of 12 m/min (472 ipm) in X and 10 m/min (394 ipm) in Z
Limitations
- The shortest bed is 2,150 mm (84.65 in) between centers, so short work is better placed on the GP-GA-47FII, which stops at 1,500 mm (59.05 in)
- Grinding diameter stops at 400 mm (15.75 in); the GP-57N at 550 mm (21.65 in) and the GP-67N at 650 mm (25.59 in) exist for larger work
- The wheel motor is listed at 15 kW (20 hp) with no higher rating shown, where the GP-GA-47FII offers 22 kW (30 hp) as an option
- Okuma's headline table gives no machine weight, floor space or work weight between centers; get the full specification sheet before planning a foundation
Best For
Frequently Asked Questions
01
Okuma lists three: 2,150, 2,650, or 3,150 mm (84.65, 104.33, or 124.02 in). The maximum grinding diameter is 400 mm (15.75 in) on all three, so the choice is purely about part length. Allow for the length taken up by the drive arrangement and workholding when matching a shaft to a bed.
02
Only in swing, as far as Okuma's headline figures show. The GP-47N grinds up to 400 mm (15.75 in), the GP-57N up to 550 mm (21.65 in) and the GP-67N up to 650 mm (25.59 in). All three share the 2,150 to 3,150 mm center distances, the 760 × 304.8 mm wheel size, the 130 mm wheel width and the 15 kW (20 hp) wheel motor.
03
The wheel size is listed as 760 × 304.8 mm (30 × 12 in) and the wheel width as 130 mm (5.12 in). It is driven by a 15 kW (20 hp) wheel spindle motor. A 130 mm face lets journals narrower than that be plunge ground in a single infeed; longer surfaces are traverse ground along the Z axis.
04
Part length decides it. Both list a 400 mm (15.75 in) maximum grinding diameter and a 760 × 304.8 mm (30 × 12 in) wheel size. The GP-GA-47FII is the short-bed machine, with center distances of 350 / 650 / 1,000 / 1,500 mm, a 150 mm (6 in) wheel width and a 22 kW (30 hp) motor option. The GP-47N starts at 2,150 mm (84.65 in) between centers and runs to 3,150 mm (124.02 in).
05
The workhead speed range is 10 - 400 RPM and the workhead center is MT5. The 10 RPM floor is useful on shafts close to the 400 mm (15.75 in) capacity, where work surface speed climbs quickly with rotation.
