Jiangyin Suofei Electronic Technology Co.,Ltd. , https://www.suofeiscales.com
How to improve the qualification rate of short cylindrical roller bearings
**How to Improve the Qualification Rate of Short Cylindrical Roller Bearings**
Home > Bearing Knowledge > How to Improve the Qualification Rate of Short Cylindrical Roller Bearings
Source: China Bearing Network | Time: February 5, 2014
---
Short cylindrical roller bearings are known for their high rotational precision, accurate fit, and ability to handle primary radial loads. They are commonly used in large precision machine tools and finishing equipment. Recently, this type of bearing has become a key product within Luo Axis Group’s large-scale bearing business unit, accounting for about one-third of the unit’s production value. However, due to outdated production methods and processes, the qualification rate remains low—only around 60%. This inefficiency leads to excessive data processing, increased working hours, and ultimately affects the overall economic performance of the business unit.
The process optimization focused on the "32672" model, which has the highest annual output. By optimizing its layout and production techniques, the goal was to achieve better economic returns and improve efficiency across other similar bearing types.
### Current Production Challenges
1. The inner and outer rings of the "32672" bearing are made from Gcr15simn steel, which has a large size series. Controlling deformation during heat treatment and quenching is difficult, often resulting in elliptical shapes that cannot be ground properly after quenching, leading to over-scaling of the raceways.
2. Due to uneven quenching, the material composition is inconsistent, causing non-uniform residual stress. This makes it hard to maintain stable raceway scaling during grinding, making it difficult to meet process standards.
3. The initial grinding process suffers from aging machinery, which reduces the spindle precision of the grinding head. This leads to rough grinding with significant surface irregularities, affecting final grinding quality and causing scale differences.
4. Inadequate skills and poor coordination also contribute to over-grinding of the raceways, which impacts the installation clearance of the entire bearing. This results in unclear or improper clearance, leading to instability during operation.
These issues have kept the pass rate at only 60%, while increasing unnecessary labor, processing time, and material waste.
### Improvement Plan and Methods
To address these challenges, several improvements were implemented:
1. **Heat Treatment Optimization**: Collaborating closely with the heat treatment plant to control deformation and reduce residual stress. Adjustments were made based on the shortening data provided by the plant to ensure sufficient grinding allowance after quenching.
2. **Additional Tempering Process**: A tempering step was added to eliminate internal stresses and stabilize the raceway scale after final grinding.
3. **Machine Tool Overhaul**: Upgrading the machine tools to improve spindle rotation accuracy and control feed rates, thereby enhancing the surface finish of the raceways and reducing over-grinding.
4. **Process Layout Adjustment**: Reorganizing the process flow to focus on the inner ring, especially when dealing with over-grinding. A method was developed to undercut the jacket and adjust the middle diameter of the cage hole to ensure better matching.
5. **Standardized Raceway Finishing**: Ensuring uniformity in raceway dimensions by controlling the scale within a small range, reducing variations between batches and improving the matching qualification rate significantly.
After implementing these changes, the matching rate of the "32672" bearing improved from 60% to over 96%. This not only reduced the repair rate but also saved labor hours, data processing, and production costs.
---
**Related Bearing Knowledge**
Understanding how to distinguish genuine NSK bearings through smooth timing protection. Learn about the common smooth methods used in high-speed bearings and the detailed structure of large motor bearing housings.
**FAG Bearing Information**
---
This article links to [http://](http://)
Please cite the China Bearing Network: [http://](http://)
Previous: The Difference Between Ball Bearings and Roller Bearings
Next: The Characteristics of Sliding Bearings