What are important tests for chains?


In order to ensure chains high quality, MAXTOP chains will go through several inspections and tests to assure that the produced chain meets the specifications. We are going to introduce you some representatively important tests according to their purpose by the test.

1. Push-Out Force

The purpose is for testing the tightness between outer plate and pininner plate and bush.
If the push-out force is not good, it might cause the separation for pins from outer plates or bushes from inner plates.

2. Length Measurement

When the length of chains is too long or too short, it would cause the chain can’t be matched with the sprocket or make noise during operation.
Therefore, it is necessary to measure whether the pitch of the chain after assembly is correct.
For example, the pitch of ANSI 80 is 25.4 mm but it is impossible for each plate pitch after production to be exactly 25.4 mm due to manufacturing tolerance.
For that reason, it could make the chain after assembly too long or too short due to the accumulation of production tolerance on each plate.
Length measurement is to ensure that the pitch of the chain after assembly is within the standard tolerance.

3. Pre-Stretching (Pre-Loading)

After chain assembled, applying an initial load to the chain, is called pre-stretching.
The initial load is the 1/3 of breaking load.
After pre-stretching, it could make each components more tightly matched, reduce the chain initial wear when using on the machine and improve chain’s fatigue.

4 Salt Spray Test

According to ASME B117, spray on the tested sample with 5% salt water and by unit time/rust situation to measure its anti-rust ability.
It is commonly used to test the anti-rust ability for surface coating chains, stainless steel chains, anti-rust lubricant, etc.

Extended Reading:

Anti-Corrosion Chain Testing Standard - Salt Spray Test

ComparingAnti-rust Chains - Find Out the Most Suitable Application

5. Wearing Test

It is used to test the wear resistance of a chain, which is also the durability of a chain.
Currently, there is no international standard for chain wearing test. Only JCAS (Japan Chain Association) has stipulated the wear test conditions for motorcycle chains.
MAXTOP wear testing machine was designed by referring to the standard.
Since the testing methods from different manufacturers may not be the same, the test results cannot be compared.

Extended Reading:

WearingTest Method for Roller Chains

6. Ultimate Strength (Breaking Load or Tensile Strength) Test

The purpose is to test whether the ultimate strength of the chain is beyond the minimum set up by the International Standard.
If it is lower than what International Standard set up, it could mean that there were problems during the production.
Poor heat treatment on components or missing parts in the chain may cause its ultimate strength to be too low. When it is too low, the chain may break during use.

Extended Reading:

TensileTest Method for Roller Chains

7. Fatigue Test

The purpose for the testing is to find out under what tensile load the chain will never break.
For general chains (excluding stainless steel chains), the fatigue strength is equivalent to the maximum allowable load.

Extended Reading:

Fatigue Test Method for Roller Chains

The differences between Ultimate Strength and Fatigue

The ultimate strength is a destructive test by forcing the chain to fail under stress factors.
It is one of the reference index for chains quality but not the most important one.
Fatigue test is much closer to the chain actual use and also the most important reference index for chains quality.

The ultimate strength is somewhat correlated with fatigue strength, but not absolutely.
Under the same specifications, if the fatigue is high, it could mean that their tensile strength is not bad but may not be very high. High ultimate strength does not mean high fatigue (sometimes maybe lower). However, low ultimate strength could mean the chain also has low fatigue.

Because the fatigue test equipment is expensive and the test is also time-consuming.
It is generally to divide the ultimate strength value by 6-10 as the fatigue strength for the factories without fatigue testing equipment.

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