Wearing Test Method for Roller Chains

Good wear resistance is one of the elements for high-quality chains. Through test, we can find out the quality of chain production and where to improve to maintain MAX TOP quality.  

Why is the chain wear so important?

Under the conditions of good and proper maintenance, we can measure the chain elongation to check working life.

Poor quality chain may have premature elongation and needs to be adjusted the tension between sprockets or replaced frequently, which lead to production interruption and higher maintenance cost.

Therefore, wear resistance is one of the important characteristics of high-quality chains.

| Chain wear resistance is related to following factors

1.Raw material of the each chain parts: 

The wearing is caused by the rubbing between the pin, bush, and roller.

During operation, pin, bushing and roller rub each other and cause wearing.

The quality of the steel materials directly affect the wear resistance of the chain. In terms of wear ability, alloy steel is better than carbon steel,

and case hardened steel (carburized steel) is better than through hardened steel.

2. Heat treatment: 

The hardness of metal is proportional to wear resistance.

However, higher the hardness is, the more brittle the chain and components would be it would decrease the chain’s tensile strength and fatigue strength.

Good and proper heat treatment should be able to improve the hardness and wear resistance while maintaining good performance of tensile and fatigue strength.

3. High-quality parts and precise assembly:

High-quality parts and precise assembly of roller chains ensure consistent chain pitch allowing the chain contact the sprocket smoothly.

The smooth contact between chain and sprocket can also reduce the noise and vibration when the chain is running, which is beneficial to reduce chain wearing. 

4. Pre-stretched:

Pre-stretched align each chain components such as link plate, roller, bushing and pin.

It minimizes initial stretch of roller chains.

5. Chain and sprocket installation: 

Place sprocket in approximate alignment. Do not twist the chain during installation, and keep the chain properly tension to avoid abnormal wearing.

6. Maintenance:

Proper maintenance and lubrication are always the best way to extend chain service life.

| How the chain elongation tested and measured

1. At present, there is no international standard for chain wear test.

Roller chain manufacturers usually conduct the wear test by simulating the actual operation of the chain.

The most common test method is to drive roller chain by two sprockets.

Driving sprocket provides power and control the speed while the driven sprocket powered by pneumatic cylinder or oil hydraulic cylinder control the load applied to the chain.

The picture shows the structure of our wear-resistant testing machine. Driving sprockets is on the left hand side, and driven sprockets powered by pneumatic cylinder imposes tension on the right hand side.

2. Example of Testing Condition

Since there is no international standard for chain wear test, the conditions of chain wear testing are set by each manufacturer. The following example is the testing condition for our 428H O-Ring chain.

Chain Length: 130 Pitch

Chain Load: 70 kgf.

Drive Sprocket: Driving sprocket 15T; driven sprocket 41T.

Chain Speed: 457.2M / min (driving sprocket 15T*2400rpm, equivalent to motorcycle speed 80km / hr)

3. Chain Elongation Measurement

Since the chain length will be elongated and worn out after testing, the original length should be measured before testing.

Measure the change of chain length every time period or mile (e.g. every 20hrs or every 1000km) until the chain worn out more than 1.5%.

Note: If the chain keep running after the reach to elongation of 1.5%, the chain and the sprocket tooth engagement may have some problems, which might break the chain or damage the sprocket

How to calculate Chain Elongation:

Example:

Original length before testing: 1017.47mm / 80 Pitch

Measured length after testing 5000km: 1017.83mm / 80 Pitch

Chain elongation (%): [(1017.83-1017.47)/1017.47]*100%=0.035%

Measured length after testing 10000km: 1019.14mm / 80 Pitch

Chain elongation (%): [(1019.14-1017.47)/1017.47]*100%=0.164%

4. Chain Wear Test Curve

Example 1: 428H O-Ring wear resistant testing curve

Example 2: 40 chain wear resistant test curve

| Conclusion: Wear Test Purpose and Benefits

1. Continuous improvement of chain quality: by testing, we can verify whether improvement of heat treatment, new materials, and surface treatment technology can increase chain working life.
2. New product development: To test whether the wear resistance of the new chain meets the requirement and expectation.
3. New oil / lubrication performance and development: To test whether the wear resistance of the new oil meets the requirement.