Design Principles
To fully leverage the performance of AXRY-NGX bearings, the design of the adjacent construction is critical. The overall shaft system must be considered, including fits, connection part precision, etc., to achieve optimal results.
Key Points
- Geometric errors in adjacent construction cause bearing deformation and higher friction torque
- Asymmetric housings deform when heated, increasing bearing preload
- Assembly errors may cause friction torque increase
Press Fits
When fits are excessively tight, radial bearing preload increases, resulting in:
| Effect | Consequence |
|---|---|
| Increases | Surface pressure in the raceway, bearing friction, bearing warming, and wear |
| Decreases | Maximum speed and bearing life |
Clearance Fits
Warning
If the rotating bearing ring is not supported across the whole surface in clearance fits, the axis of rotation (bearing axis to table axis) is likely to be displaced.
Clearance tolerances can accumulate with bore clearances, potentially adding to radial runout errors.
The page advises against relying on clearance fits for temperature compensation without precise ring knowledge, as risks include vibrations, runout errors, and repeatability failures.
Minimum Wall Thickness
| Bearing Size | Min. Wall Thickness (mm) | Max. Passage (mm) |
|---|---|---|
| AXRY 180-NGX | 19 | 142 |
| AXRY 200-NGX | 22 | 156 |
| AXRY 260-NGX | 26 | 209 |
| AXRY 325-NGX | 27 | 271 |
| AXRY 395-NGX | 27 | 340 |
| AXRY 460-NGX | 30 | 400 |
| AXRY 580-NGX | 36 | 508 |
| AXRY 650-NGX | 45 | 560 |
Shaft Side Requirements
Shaft Shoulder Design
- Shaft shoulder should provide sufficient support area
- Shaft shoulder height should be sufficient to withstand axial loads
- Good perpendicularity between shaft shoulder and bearing inner ring face
Shaft Journal Precision
| Item | Recommended Precision |
|---|---|
| Roundness | IT5 or better |
| Cylindricity | IT5 or better |
| Surface roughness Ra | ≤ 0.8 µm |
| Shoulder perpendicularity | ≤ 3 µm / 100 mm |
Housing Side Requirements
Housing Bore Precision
| Item | Recommended Precision |
|---|---|
| Roundness | IT5 or better |
| Cylindricity | IT5 or better |
| Surface roughness Ra | ≤ 1.6 µm |
| Face perpendicularity | ≤ 3 µm / 100 mm |
Housing Design Points
- Symmetric design - Avoid thermal deformation from asymmetric structures
- Sufficient wall thickness - Ensure housing rigidity
- Lubrication channels - Reserve relubrication channel positions
- Locating pin holes - Correspond with bearing locating holes
Mounting Surface Requirements
Bolt Hole Layout
- Bolt holes should be evenly distributed around the bearing outer diameter
- Bolt specifications should meet bearing fastening requirements
- High-strength bolts (Grade 8.8 or higher) recommended
Mounting Surface Flatness
| Bearing Size | Mounting Surface Flatness [µm] |
|---|---|
| 180 - 260 | ≤ 5 |
| 325 - 460 | ≤ 7 |
| 580 - 650 | ≤ 10 |
Thermal Design Considerations
Thermal Management Recommendations
- Minimize contact surface between motor stator and rotary table housing to reduce heat flow
- If possible, do not connect stator cooling jacket to rotary table housing
- Preferably connect torque motor rotor flange to rotary table plate rather than bearing, to keep heat flow through bearing as low as possible
- Maximize distance between motor and bearing to reduce heat transfer from rotor to bearing
- Make rotary table plate bearing centering sufficiently rigid for high system rigidity
Recommended Assembly Sequence
- Clean - Thoroughly clean all mating surfaces
- Inspect - Verify shaft and housing dimensional accuracy
- Position - Align bearing locating hole with housing locating pin
- Install - Place bearing in housing
- Preload - Preload bolts evenly in diagonal sequence
- Final Tightening - Final tightening to specified torque
- Verify - Measure friction torque to confirm correct installation
Assembly Tip
It is recommended to rotate the bearing and measure friction torque during assembly. This can detect serious errors in adjacent construction geometry, bolt connections, or additional components.