The Invisible Film That Carries the Load

A bearing "rolling" contact is never truly metal-on-metal. A thin elastohydrodynamic (EHL) lubricant film - only a few micrometres or less thick - separates the rolling elements from the raceway and carries the load. Keeping that film intact is the whole job of lubrication.

EHL Film Thickness

Under load the contact zone flattens elastically and the local pressure (measured in GPa) is enormous. The lubricant's viscosity rises sharply under that pressure, letting a stable film form. Film thickness depends mainly on speed, viscosity and load: faster and thicker (higher-viscosity) lubricant builds a thicker film; heavier load squeezes it thinner. The ratio of film thickness to surface roughness (the λ factor) tells you whether you are in full-film, mixed or boundary lubrication.

Grease vs Oil

Grease is the default for sealed, general-duty bearings: a thickener holds oil in place, simplifying sealing and maintenance. Oil (splash, bath, mist or jet) is preferred for very high speeds, high temperatures or when heat must be carried away. Selecting the right base-oil viscosity for the operating speed and temperature is more important than the brand.

Failure Modes Tied to Lubrication

Starvation or wrong grade leads to metal-to-metal contact, scoring and early fatigue. Over-greasing can cause churning, heat and seal damage. Contaminated lubricant introduces abrasive particles that dent raceways. Correct type, amount and re-lubrication interval are therefore part of any reliability program.

How KMK Bearing Applies This

At KMK Bearing (SINO BEARINGS, KMK brand) these principles guide every order we manufacture in Chengdu, China. Our in-house process chain - forging, heat treatment, precision grinding, superfinishing and cleanroom assembly - is built to the standards described above, whether the part is a standard catalog bearing or a custom-engineered solution.

• 20+ years of precision bearing manufacturing
• Materials from chrome steel to 17-4PH stainless steel and full ceramic (ZrO2, Si3N4)
• In-house heat treatment and metrology to P4/P2 (ABEC 7/9) precision
• Custom designs and low-MOQ prototyping from drawings or samples

Discuss your application with kevin@sinoti.com or browse our bearing catalog.

SINO BEARINGS (KMK) - Perfect Quality -- Great Service -- Customized.

Source: SINO BEARINGS