Okuma GP-N
- Grinding
- |Large CNC cylindrical grinder

The cylindrical grinding machines of the GP/N Series are one of the most successful achievements for the production of large components for cars, motorcycles and hydraulic components, the fruit of the consolidated experience of OKUMA, a world-leading manufacturer, in these sectors.
Their particular ease of use allows the machine to reach high levels of productivity even without skilled operators.
The machine structure, with a single body for bed and table, provides high rigidity, and careful design has made it possible to achieve perfect machine balance.
Newly designed spindle built with high-pressure hydrodynamic bearings that guarantee a maximum rotational error of 0.02 µm and a rigidity of 100 Kg/µm; these features allow high stock removal capacity. The hydrodynamic bearings involve no contact with the shaft, which is therefore not subject to deterioration.
The grinding wheel head slides on 'V' and flat guideways coated with anti-friction material to ensure accurate positioning and linear movement with a low friction coefficient.
OKUMA OSP-P300GA control system for fully automatic machining cycles; the 0.0001 mm feed resolution on both controlled axes allows extremely high sensitivity in operations requiring high precision.
Okuma's GP-N series answers the need for OD grinding of large components: shafts, pins and hydraulic parts up to 3,150 mm between centres and up to 1,800 kg. Three machine sizes – GP-47N, GP-57N and GP-67N – cover grinding diameters of 400, 550 and 650 mm, each in three lengths. A hydrodynamic wheel spindle and a one-piece bed-and-table structure support heavy stock removal without giving up accuracy, while the Okuma OSP-P300GA control works in 0.0001 mm increments.
| Parameter | GP-47N (215) | GP-47N (265) | GP-47N (315) | GP-57N (215) | GP-57N (265) | GP-57N (315) | GP-67N (215) | GP-67N (265) | GP-67N (315) |
|---|---|---|---|---|---|---|---|---|---|
| Axis travel (X×Z) | 475 × 2430 mm | 475 × 2930 mm | 475 × 3430 mm | 475 × 2430 mm | 475 × 2930 mm | 475 × 3430 mm | 475 × 2430 mm | 475 × 2930 mm | 475 × 3430 mm |
| Swing diameter | 430 mm | 430 mm | 430 mm | 580 mm | 580 mm | 580 mm | 680 mm | 680 mm | 680 mm |
| Max grinding diameter | 400 mm | 400 mm | 400 mm | 550 mm | 550 mm | 550 mm | 650 mm | 650 mm | 650 mm |
| Max workpiece weight | 1500 kg | 1500 kg | 1500 kg | 1500 kg | 1500 kg | 1500 kg | 1800 kg | 1800 kg | 1800 kg |
| Grinding wheel – diameter | 760 mm | 760 mm | 760 mm | 760 mm | 760 mm | 760 mm | 760 mm | 760 mm | 760 mm |
| Workhead rotation speed | 5–150 rpm | 5–150 rpm | 5–150 rpm | 5–150 rpm | 5–150 rpm | 5–150 rpm | 5–150 rpm | 5–150 rpm | 5–150 rpm |
| Grinding wheel – spindle power | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) | 15 kW (22 kW optional) |
| Spindle – taper / mount | CM 6 | CM 6 | CM 6 | CM 6 | CM 6 | CM 6 | CM 6 | CM 6 | CM 6 |
| Distance between centers | 2150 mm | 2650 mm | 3150 mm | 2150 mm | 2650 mm | 3150 mm | 2150 mm | 2650 mm | 3150 mm |
| Wheel peripheral speed | 45 m/s | 45 m/s | 45 m/s | 45 m/s | 45 m/s | 45 m/s | 45 m/s | 45 m/s | 45 m/s |
| Grinding wheel – width | 130 mm | 130 mm | 130 mm | 130 mm | 130 mm | 130 mm | 130 mm | 130 mm | 130 mm |
| Grinding wheel – bore | 304.8 mm | 304.8 mm | 304.8 mm | 304.8 mm | 304.8 mm | 304.8 mm | 304.8 mm | 304.8 mm | 304.8 mm |
| Machine dimensions (X×Y) | 8350 × 3360 mm | 9350 × 3360 mm | 10350 × 3360 mm | 8350 × 3360 mm | 9350 × 3360 mm | 10350 × 3360 mm | 8350 × 3360 mm | 9350 × 3360 mm | 10350 × 3360 mm |
| Machine weight | 13000 kg | 14000 kg | 15000 kg | — | — | — | — | — | — |
| CNC – model | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA | Okuma OSP-P300GA |
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