The selection of bearing materials has an impact on bearings

Load-bearing capacity and fatigue resistance

Impact: The purity, hardness and contact fatigue strength of the material determine how much load the bearing can withstand.

Explanation: If the material contains excessive impurities or has insufficient hardness, the bearing raceway or the surface of the rolling elements are prone to fatigue spalling (metal shedding in sheet form) under heavy loads, resulting in premature failure of the bearing. High-quality bearing steel (such as high-carbon chromium steel) can provide extremely high compressive strength and fatigue life.

Wear resistance and friction coefficient

Impact: Determines the wear rate and heat generation of the bearing during operation.

Explanation: Materials with higher hardness (such as ceramics) tend to be more wear-resistant. If the friction coefficient of the material is high, it will cause severe heating, which not only consumes energy but also may lead to lubrication failure due to overheating.

Limiting rotational speed and anti-sticking property

Impact: The high-temperature performance and anti-adhesion properties of the material determine whether the bearing can operate at high speeds.

Explanation: At high speeds, centrifugal force and frictional heat are extremely high. Ordinary steel will soften at high temperatures. If the material has poor anti-adhesion properties (such as when it comes to friction with the same type of metal), once the lubrication is suddenly interrupted, the rolling elements and the raceway will easily "bond" together instantaneously (gummed up), causing the bearing to become stuck.

Corrosion resistance

Impact: Determines in what kind of medium the bearing can operate.

Explanation: Ordinary bearing steel (GCr15) is highly prone to rusting. Once it comes into contact with water, moisture, or corrosive chemicals, its surface will rapidly corrode, causing the bearing to fail. At this point, stainless steel, ceramics, or high-molecular materials must be selected.

Dimensional stability and thermal expansion

Impact: Affects bearing clearance and installation accuracy.

Explanation:When the temperature changes significantly, if the thermal expansion coefficient of the material does not match the shaft or bearing housing, the clearance may become too large (causing vibration) or too small (resulting in jamming). For example, all-Ceramic Bearings have an extremely small thermal expansion coefficient and are suitable for applications with large temperature fluctuations.

High-carbon chromium bearing steel

Representative materials: GCr15 (SUJ2, 52100)

Advantages: Extremely high hardness, good contact fatigue strength, moderate cost, mature manufacturing process.

Disadvantages: Prone to rust, not resistant to high temperatures (maximum usage temperature is approximately 120°C to 180°C), non-magnetic.

Typical applications: General machinery, motors, automotive gearboxes, precision machine spindle (the largest usage volume).

Stainless steel

Representative materials: 9Cr18, 440C

Advantages: Corrosion-resistant, capable of operating in water vapor and weak acids and bases, can be partially used in low-temperature and vacuum environments.

Disadvantages: Slightly lower hardness than GCr15, more expensive, slightly poorer heat conductivity.

Typical applications: Food machinery, medical equipment, chemical pumps, marine engineering, diving motors.

Ceramic materials

Representative material: Silicon nitride (Si₃N₄)

Advantages: Low density (about 40% of steel), excellent high-speed performance; Insulation (anti-electrochemical corrosion); High temperature resistance (up to over 800°C); Good self-lubrication.

Disadvantages: High brittleness (sensitive to severe impact), difficult to process, expensive (usually a composite ceramic Ball bearing, where the raceway is steel and the balls are ceramic).

Typical applications: Electric spindle (anti-electrochemical corrosion), high-speed machine tools, wind power speed increasers, aerospace, vacuum pumps.

Polymer materials

Representative materials: PEEK, PTFE, phenolic resin

Advantages: Self-lubricating (can operate without oil), resistant to strong acids and alkalis, lightweight, shock absorption and noise reduction

Disadvantages: Low strength, extremely poor heat conductivity (easily expands due to heat), poor dimensional stability, prone to aging.

Typical applications: Beverage filling lines, textile machinery, food conveyor belts (need to avoid oil contamination), underwater bearings.

Copper alloy / Anti-friction material

Representative materials: Brass, Bronze

Advantages: Low friction coefficient, good embedment (able to absorb minor impurities), fast heat conduction.

Disadvantages: Strength is much lower than that of bearing steel.

Typical applications: Mainly used as bearing bush materials or cage materials for sliding bearings.

When choosing the material for bearings, a trade-off is usually made based on the following priorities:

Load type and size: For heavy loads and impact loads, steel with good fatigue resistance must be selected (such as GCr15 carburized steel or high-carbon chromium steel).

Environmental factors: Select stainless steel if there is water or corrosive medium; choose ceramics if there is an electrochemical corrosion risk; select ceramics or special high-temperature steel for high-temperature environments.

Speed factor: At extremely high rotational speeds, ceramic rolling elements (with their light weight and low centrifugal force) are the ideal choice.

Lubrication conditions: In cases of boundary lubrication or when there is no supply of oil, self-lubricating materials (such as PTFE composite materials or porous oil-containing metals) should be considered.

Economy: When conditions permit, the most economical GCr15 series bearing steel should be selected.