NTN imported bearings show the reason for inserting spiral traces

**NTN Imported Bearings: The Reason Behind Spiral Marks** Home > Bearing Knowledge > The Cause of Spiral Traces in NTN Imported Bearings This article explores the reasons behind spiral traces that can appear on the surface of NTN imported bearings during fine grinding. These marks, often visible to the naked eye, are not only unsightly but can also affect the performance and lifespan of the bearings. Spiral traces typically occur due to poor flatness of the grinding wheel. When the grinding wheel is uneven—showing concave or convex areas—it only makes contact with certain parts of the workpiece during grinding. As the workpiece or grinding wheel reciprocates multiple times, these irregularities create a spiral pattern that becomes noticeable. The pitch of these spirals depends on the speed of the worktable and the rotation speed of the workpiece, as well as the alignment between the grinding wheel axis and the worktable guide rails. ### Common Causes of Spiral Traces: 1. **Poor Rigidity of V-Guideways**: If the V-shaped guide rails are not rigid enough, the grinding wheel may shift during operation, causing only the edge of the wheel to touch the workpiece surface. 2. **Unstable Workbench Speed**: During repair or maintenance, an unstable workbench speed can lead to inconsistent grinding, resulting in spiral marks. 3. **Low-Rigidity Workpieces**: If the workpiece itself is not rigid, it can vibrate or move slightly during grinding, contributing to the formation of spiral patterns. 4. **Contamination on the Grinding Wheel**: Accumulation of debris, such as broken abrasive grains or metal shavings from the workpiece, can interfere with the grinding process. It's important to clean the grinding wheel regularly using cooling water to prevent this. 5. **Poor Dressing of the Grinding Wheel**: Inadequate dressing can leave bumps or irregularities on the wheel’s surface, leading to uneven grinding and spiral marks. 6. **Excessive Lubricating Oil on Guide Rails**: Too much oil on the workbench guides can cause the table to float, affecting the stability of the grinding process. 7. **Machine Tool Inaccuracy**: If the machine tool lacks precision, it can contribute to the formation of spiral traces. 8. **High Grinding Pressure**: Excessive pressure applied during grinding can cause uneven wear and result in spiral marks on the bearing surface. ### Additional Issues Identified Through Ferrography: 1. **Bearing Burned Tile**: Iron spectrum analysis shows large alloy abrasive grains and black metal oxides, indicating overheating or excessive friction. 2. **Fretting Wear on the Bearing Back**: Abnormal iron concentration and sub-micron iron particles suggest micro-motion wear, often caused by improper lubrication. 3. **Corrosion on the Bearing Journal**: High moisture or acid value in the lubricating oil can lead to corrosion on the bearing surface, visible through spectral analysis. 4. **Surface Flaking on the Bearing Tile**: Fatigue-induced wear particles and layered abrasive grains are commonly found in ferrography, indicating potential material failure. 5. **External Strain on the Bearing Surface**: Non-ferrous metal abrasive grains in the iron spectrum may indicate foreign contamination or improper machining. 6. **Surface Corrosion on the Bearing Tile**: Abnormal non-ferrous metal elements and sub-micron wear particles in the iron spectrum suggest chemical degradation, often due to moisture or acidic lubricants. 7. **Strain on the Bearing Journal Neck**: Presence of iron-based cutting abrasive particles and tempering color on the metal surface indicates heat stress or mechanical overload. --- **Related Bearing Knowledge:** - The effect of bearing smoothness - Common faults in bearing operation - How to identify and address bearing issues - Layout and use of imported linear motion ball bearings - Characteristics of acid-resistant plastic needle bearings - Understanding the features of imported bearings For more information, visit China Bearing Network. Link: http:// Source: China Bearing Network | Date: April 8, 2014 Previous: The Use of Bearings in Different Applications Next: What Is the Working Principle of Gear Pumps?

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