NRT 325 B
Axial-radial cylindrical super-precision roller bearingAxial-radial cylindrical super-precision roller bearings can accommodate radial loads, axial loads in both directions and moment loads, whether acting singly, or simultaneously, in any combination. With high running accuracy, high load capacity and rigidity, SKF super-precision axial radial cylindrical roller bearings are ideal for rotary tables, indexing heads, and multi spindle heads. The bearing minimizes noise, vibration and heat generation.
- Accommodate radial and axial loads in both directions
- Designed for low-medium speed performance
- Handle moment loads
- Close tolerances
- Minimizing noise, vibration and heat generation
Description
Dimensions
| d | 325 mm | Bore diameter |
|---|---|---|
| D | 450 mm | Outside diameter |
| H | 60 mm | Height |
| d1 | 415 mm | Shoulder diameter inner ring – large shoulder |
| C | 20 mm | Outer ring (housing washer) width |
| H1 | 40 mm | Distance |
| J | 342 mm | Inner ring (shaft/locating washer) hole pitch circle diameter |
| J1 | 430 mm | Outer ring (housing washer) hole pitch circle diameter |
| N | 9.3 mm | Inner ring (shaft/locating washer) through hole |
| N1 | 15 mm | Inner ring (shaft washer) sinkhole |
| N2 | 9.3 mm | Outer ring (housing washer) through hole |
| a | 8.2 mm | Inner ring (shaft washer) sinkhole depth |
| r1 | min. 0.6 mm | Outer ring (housing washer) chamfer dimension |
| r2 | min. 0.6 mm | Chamfer dimension |
Calculation data
| Basic dynamic load rating – radial direction | C | 134 kN |
|---|---|---|
| Basic static load rating – radial direction | C0 | 450 kN |
| Basic dynamic load rating – axial direction | C | 153 kN |
| Basic static load rating – axial direction | C0 | 1 660 kN |
| Attainable speed for grease lubrication | 110 r/min | |
| Attainable speed for oil-air lubrication | 220 r/min | |
| Axial preload | 12 kN | |
| Axial unloading force | 26 kN | |
| Frictional moment | CRL | 45 N·m |
| Axial stiffness for preload A (sets of two brgs back-to-back or face-to-face) | 28 600 000 kN/µm | |
| Axial stiffness for preload B (sets of two brgs back-to-back or face-to-face) | 8 900 000 kN/µm | |
| Moment stiffness | 427 kN·m/mrad |
Mass
| Mass bearing | 25 kg |
Rotary table
| Guideline rotary table diameter | 700 mm |
Mounting information
| Size | M8 | |
| Number of bolts | 2 | |
| Angle between bolts | 180 ° |
| Size | G | M12 |
|---|---|---|
| Number of threads | 3 | |
| Angle between threads | 120 ° |
| Bolt size | M8 | |
| Pitch | α | 10 ° |
| Number of bolts | 34 | |
| Number of bolts omitted at retaining bolts position | 2, 180° apart | |
| Tightening torque (Bolt grade 10.9) | 34 N·m |
| Bolt size | M8 | |
| Pitch | α | 10 ° |
| Number of bolts | 33 | |
| Number of bolts omitted at removal thread position | 3, 120° apart |
