Studer S121
Key Specifications
axes
min bore diameter
max bore diameter
max workpiece length
max workpiece diameter at chuck
max workpiece weight
Overview
The Studer S121 is a universal internal cylindrical grinding machine from United Grinding's Studer division, engineered for high-precision grinding of bores, internal profiles, faces, and tapers in precision components including dies, gauges, bearing housings, hydraulic cylinders, and complex workpiece bores.
The S121 is a dedicated internal grinding machine, configured with a stationary workhead and a high-speed internal grinding spindle that traverses into bore features. The machine handles bores from 1 mm (0.04 in) minimum to 250 mm (9.84 in) maximum diameter, and workpieces up to 350 mm (13.8 in) length. Maximum workpiece diameter at the chuck is 400 mm (15.7 in), and maximum workpiece weight is 150 kg (330 lb).
The grinding spindle is available in multiple speed configurations, with maximum spindle speeds from 60,000 rpm for micro-bore applications down to 10,000 rpm for larger bore diameters. The C-axis workhead provides continuous rotation with speed range suitable for both low-speed facing operations and higher-speed internal grinding. A B-axis wheelhead swivel of ±30 degrees enables taper and angular bore grinding without workpiece repositioning.
All linear axes use Studer's StuderGuide hydrostatic guideway technology. Control runs on the Studer StuderWIN interface with StuderGRIND software, which includes dedicated programming modules for internal grinding cycles including plunge, traverse, taper, and complex profile operations.
The S121 supports integration with loading automation including portal loaders and robot cells for production environments. A full measuring probe system is available for in-process bore measurement and automatic size compensation.
New Studer S121 machines are typically priced in the $380,000-$580,000 range. Used units appear in the $170,000-$310,000 range.
Full Specifications
| Parameter | Value |
|---|---|
| Axes | 4 (X, Z linear + C workhead rotation, B wheelhead swivel) |
| Min Bore Diameter | 1 mm (0.04 in) |
| Max Bore Diameter | 250 mm (9.84 in) |
| Max Workpiece Length | 350 mm (13.8 in) |
| Max Workpiece Diameter At Chuck | 400 mm (15.7 in) |
| Max Workpiece Weight | 150 kg (330 lb) |
| Wheelhead Swivel | ±30 degrees |
| Internal Spindle Max Speed | 60,000 rpm (micro), 10,000 rpm (large bore) |
| Guideway System | StuderGuide hydrostatic/aerostatic |
| Machine Dimensions | 3,400 x 1,900 x 1,950 mm (133.9 x 74.8 x 76.8 in) |
| CNC Control | StuderWIN with StuderGRIND on Fanuc CNC |
| From | To |
| Newark New York | Las Vegas (LAS) |
| San Francisco | Newark/New York (EWR) |
| Los Angeles | Newark/New York (EWR) |
Strengths & Limitations
Strengths
- 1 mm minimum bore diameter capability extends internal grinding range down to near-micro dimensions, covering a wider bore spectrum than most dedicated internal grinders
- 150 kg maximum workpiece weight accommodates large bearing housings, hydraulic manifolds, and die sets that exceed lighter machines' capacity
- ±30-degree wheelhead swivel enables taper, angular, and face grinding without unclamping the workpiece, reducing setup time significantly
- Multiple spindle speed configurations from 10,000 to 60,000 rpm ensure optimal surface speed for bore diameters from micro to 250 mm
- StuderGuide hydrostatic guideways eliminate stick-slip and vibration for the exceptional bore roundness and surface finish Studer internal grinders are known for
- StuderGRIND software includes dedicated internal grinding programming modules with parametric cycle definition and automatic multi-pass planning
Limitations
- Dedicated internal grinding configuration means external OD grinding requires a separate machine — not a universal machine for mixed OD/ID work
- High price of $380,000-$580,000 new places it above general-purpose CNC lathes with grinding attachments that handle lower-precision bore grinding
- Large machine footprint of 3,400 x 1,900 mm and 150 kg capacity requires solid floor mounting and adequate crane or lifting equipment for workpiece loading
- Hydrostatic guideway maintenance requires consistent coolant quality and temperature control — a controlled environment is strongly recommended
- Specialization as an internal grinder means lower utilization in shops where external grinding volumes are higher than internal
Best For
Frequently Asked Questions
01
The S121 and S131 are both dedicated internal cylindrical grinders from Studer, with the S131 being larger in workpiece capacity. The S131 handles larger bore diameters, longer workpieces, and heavier parts. The S121 covers bore diameters up to 250 mm and workpieces up to 150 kg, while the S131 steps up to larger workpiece envelopes. The S121 is the mid-range internal grinder; the S131 targets large component grinding.
02
Yes. With high-speed spindle configurations reaching 60,000 rpm, the S121 can grind bores from 1 mm diameter with appropriate small-diameter internal grinding pins. This makes it capable of precision bore grinding in miniature hydraulic components, precision instruments, and medical device components alongside its standard bore diameter range.
03
In-process gauging is available as an option on the S121. Studer integrates measuring probe systems that measure bore diameter during the grinding cycle and feed corrections automatically to the CNC for size compensation. This capability is critical in production environments where consistent bore tolerances across high part volumes are required.
04
New Studer S121 machines typically price between $380,000 and $580,000 depending on spindle configuration, automation integration, and measuring system options. Used units from 2014-2022 appear in the $170,000-$310,000 range on the secondary market.
Videos
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