Detect Bearing Faults In Rolling Mills With Lubricant Testing

Rolling mill bearings play a fundamental role in ensuring performance and reliability within industrial settings. When rolling mill bearings fail, it results in costly machine downtime, reduced product quality, and high repair costs. Testing lubricants is one of the most effective methods of detecting early signs of bearing failure. It is a form of preventative maintenance that is useful in identifying abnormal wear or fault conditions that will cause catastrophic equipment failures.

The Role of Rolling Mill Bearings and Their Failure
What Are Rolling Mill Bearings?
Rolling Bearings are utilized in Heavy Industrial Machines to support the Rotating Shafts, While Supporting Radial Loads and Axial Loads. Proper Operation of the Rolling Mill Bearings Allows for Accurate Continuous Processing of Metal Products (Bars, Sheets, Rods). The Rolling Mill Bearings use a Thin Layer of Lubricant Film Between the Moving Surfaces to Reduce Friction and Wear, which allows for Smooth Operation of the Machinery.

Causes for Bearing Failure
Several factors can cause bearings to fail. The common types of bearing failure include

Lack of Lubrication: If an oil or grease cannot adequately lubricate the bearing surface, it will come in contact with each other, leading to excessive wear and stress on the bearing.

Lubricant Contamination: Dirt, moisture, and/or abrasive particles in the lubricant will increase the rate of degradation.

High Temperatures and Overloading: Excessive heat will degrade the lubricant and create fatigue due to the increased temperature.

What is lubricant testing?

Used Lubricants are tested to check the condition of the lubricant and the health of the equipment. This testing process can identify an issue before it impacts the individual.

CME Testing provides you with the ability to determine:

• Wear Metals — Metals that have been worn from bearings (iron, copper, lead).

• Contamination, such as minerals and other substances that would cause failure of the component (i.e., chemicals, lubricants).

• Additive Depletion - The loss of the protective quality of a product over time.

• Viscosity -which indicates aging or overheating

Key Lubricant Tests for Bearing Failure Detection
1. Wear Metals Analysis (Elemental, spectral)
The spectral wear metal analysis test measures the concentration of trace amounts of metallic wear particles found in lubricants. High concentrations of iron or other metallic wear are an indicator of internal wear in bearings.

Significance: The increasing concentration of metal wear will provide evidence of the deterioration of bearing surfaces, no matter how minor the external symptoms may be.

2. Particle Count analysis
The count and size of particles present in a lubricant reflect how much contamination has occurred due to dust, metal, and debris that will lead to the abrasion of bearings and cause damage to them.

Significance:
The higher the particle count, the more likely that there is an increased risk of wear by abrasive means. The unusual shape of a particle could indicate specific types of failure.

3. Viscosity Testing
A lubricant's viscosity indicates its ability to provide film protection. Any change from being either too heavy or too thin will negatively impact lubricant efficiency. This may lead to lubrication starvation or thermal degradation.

4. Ferrography Analysis
Ferrography analysis determines and examines the metallic particles using magnetic separation, which allows the identification of the amount of wear to the components and determines the type and severity of the wear.

5. Moisture analysis
It detects water contamination that accelerates corrosion, reduces lubricant film strength, and promotes premature bearing fatigue.

6. Total Acid Number (TAN)
Measures oil oxidation and acidity caused by heat, aging, and contamination. Rising moisture and TAN values indicate lubricant degradation and loss of protective properties.

Detecting rolling mill bearing failures through oil testing enables maintenance to shift from reactive to predictive and proactive. By regularly analyzing the lubricant properties, wear metals, contaminants, and advanced particle signatures, engineers and maintenance professionals can uncover hidden faults, optimize maintenance scheduling, and maximize rolling mill uptime and reliability.

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