Studer S31
Key Specifications
Grinding Length (between centers)
Max Workpiece Height (center height)
Max Workpiece Weight (between centers)
External Grinding Wheel Diameter
Internal Grinding Spindle Speed
External Grinding Spindle Power
Overview
The Studer S31 is a universal cylindrical grinding machine from United Grinding Group's Studer division, designed for external and internal cylindrical grinding of medium-sized workpieces in both single-part and batch production. Introduced as a successor to the highly regarded S30 series, the S31 represents Studer's benchmark platform for versatile precision cylindrical grinding in manufacturing and tool room environments.
The S31 is built on Studer's signature Granitan S103 mineral casting base, which provides excellent vibration damping and thermal stability — critical factors in achieving the sub-micron roundness and surface finish values the machine is rated for. The machine's patented StuderGuide hydrostatic guideway system on the cross and longitudinal axes eliminates mechanical stick-slip and delivers smooth, highly accurate table movement throughout the full travel range.
The standard configuration includes a universal swiveling wheelhead that can carry two grinding spindles — one for external grinding (typically a large-diameter wheel) and one for internal grinding — allowing both OD and ID operations without workpiece rechucking. The workhead swivels for taper grinding, and the optional C-axis enables non-circular and cam grinding. Studer's StuderWIN control system provides conversational and DIN 66025 programming.
The S31 is widely used in automotive driveline component manufacturing, hydraulic and pneumatic component production, aerospace shaft grinding, and precision tool room applications. It competes directly with Schaudt, Kellenberger, and Okamoto universal cylindrical grinders in the mid-range segment.
Full Specifications
| Parameter | Value |
|---|---|
| Grinding Length (Between Centers) | 650 mm / 1,000 mm (two versions) |
| Max Workpiece Height (Center Height) | 175 mm |
| Max Workpiece Weight (Between Centers) | 80 kg |
| External Grinding Wheel Diameter | 500 mm × 63 mm |
| Internal Grinding Spindle Speed | Up to 60,000 RPM (with ISM spindle) |
| External Grinding Spindle Power | 7.5 kW |
| Wheelhead Swivel Range | 0° to 360° (manual or CNC optional) |
| Workhead Swivel Range | ±10° (manual) |
| Achievable Roundness | < 0.3 µm |
| Achievable Surface Roughness | Ra < 0.06 µm |
| Longitudinal (Z) Axis Travel | 650 mm or 1,000 mm |
| Cross (X) Axis Travel | 370 mm |
| Control System | Studer StuderWIN (Fanuc-based) |
| Machine Base | Granitan S103 mineral casting |
| Machine Weight | Approx. 5,500 kg |
| From | To |
| Newark New York | Las Vegas (LAS) |
| San Francisco | Newark/New York (EWR) |
| Los Angeles | Newark/New York (EWR) |
Specifications sourced from static.machinetools.com — verified 2026-03-28
Strengths & Limitations
Strengths
- Granitan mineral casting base provides superior vibration damping versus cast iron competitors
- StuderGuide hydrostatic guideways eliminate stick-slip for sub-micron axis precision
- Universal wheelhead with dual spindles allows OD and ID grinding in one setup
- Achieves roundness below 0.3 µm and Ra below 0.06 µm — among the best in class
- Long-standing global service network through United Grinding Group
Limitations
- High capital cost relative to conventional cylindrical grinders
- Swiveling wheelhead configuration adds setup time compared to fixed-wheel machines
- Granitan base increases machine weight and transport complexity
Best For
Frequently Asked Questions
01
Granitan S103 is a proprietary polymer concrete (mineral casting) material developed by Studer. It has approximately six times better vibration damping than cast iron and excellent thermal stability, which translates directly into lower surface roughness values and better dimensional consistency over a production shift. Studer has used Granitan as the machine base material across its product range for decades.
02
Yes. The standard S31 wheelhead configuration includes an internal grinding spindle (ISM) in addition to the external OD spindle. Speeds up to 60,000 RPM are available for the internal spindle, enabling precision ID grinding of bores down to a few millimeters in diameter without rechucking the workpiece.
03
StuderGuide is Studer's patented hydrostatic guideway system used on the cross and longitudinal table axes. By using a film of pressurized oil rather than contact bearing surfaces, it eliminates the stick-slip phenomenon common in rolling or sliding guides. This results in smoother, more precise table movement — especially important for the fine infeed increments used in finishing passes.
04
The S33 is Studer's smaller universal cylindrical grinder with a shorter maximum grinding length (175 mm between centers vs 650/1,000 mm on the S31) and lighter workpiece capacity. The S31 is designed for medium-sized industrial workpieces, while the S33 targets smaller components typical in medical devices, watch making, and precision instrument production.
05
Yes. The S31 is compatible with Studer's StuderLoader and third-party gantry or robot loading systems. Automated loading is commonly used in automotive production applications where the machine runs in a dedicated cell grinding a family of shaft parts across multiple shifts.
Videos
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