In high-speed, high-precision automation systems, the stability and longevity of the linear rail system depend heavily on the quality of its components. Shafts and bearing housing, as the key interfaces between the rail and the load, their precision and coordination will directly affect the efficiency and reliability of the overall system. In this article, we will discuss in depth the key characteristics of the shaft and their influence on the performance of the rail and briefly introduce the selection of the seat considerations bearing.
1. Shafts
The rolling balls in a linear rail directly contact the shaft’s surface, making the shaft's dimensions, tolerances, surface roughness, and hardness critical to rail performance. When manufacturing shafts, special attention should be paid to the following points:
- Surface roughness
The shaft surface should be finely finished to prevent vibration or skipping of the rolling steel balls during operation. A surface roughness of Ra 0.4 μm or better is recommended for smoother contact and longer service life. - Hardness
The optimum hardness range is HRC 60 to 64. Hardnesses below HRC 60 significantly reduce service life and increase the amount of permissible deformation, which in turn reduces load carrying capacity. On the other hand, the hardnesses above HRC 64 accelerate wear of the steel balls. Therefore, keeping the hardness of the shaft within this range helps to maintain long and stable operation. - Dimensions and tolerances
For adjustable and open-end linear bearings, the diameter of the shaft should be as close as possible to the lower tolerance limit of the inner cut circle in the sample. This helps to maintain a sufficient margin of adjustment during mounting and adjustment. - Clearance control
Zero or negative clearance may slightly increase friction, but excessive negative clearance can deform the outer cylinder, shortening bearing life.
In conclusion, shafts for linear slides must be subjected to strict quality control in terms of dimensional tolerances, surface roughness and hardness. For detailed information on shaft specifications, please refer to the technical data sheet of each rail product.
2. Bearing Housing
The selection of suitable bearings is essential to ensure the stable installation and precise operation of the linear rail system. To meet different application requirements, the structure and dimensions are suitable for most installation conditions and can be adjusted according to the operating environment and loading conditions.
- Suggested fit:
To avoid wear and vibration caused by eccentricity and interference, it is recommended to maintain a fit grade of H7/g6 between the bearing housing ID and shaft or adjust it according to the actual application. - Structural consideration:
For heavy load or long stroke applications, it is recommended to use integral bearing housing to enhance the overall rigidity and resistance to deformation.
Conclusion
High-quality shafts and precisely designed bearing housing are essential for ensuring precision, longevity, and stable operation of linear rail systems. Controlling quality from the source and selecting the right specifications for specific applications guarantees reliability and long-term performance.
When designing and selecting a linear rail system, the characteristics of the shaft and bearing housing must be carefully considered to ensure that the entire system achieves the desired performance.
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