TS ISO 4378-2

TS ISO 4378-2 is the friction-and-wear section of the terminology series for plain bearings. It brings together the most commonly used terms for the frictional behaviour and wear mechanisms associated with sliding bearings, and organises them with definitions and classification.

Plain bearings are machine elements that support relative motion between a shaft and a bearing surface without rolling elements. In this field, friction and wear strongly influence efficiency, heat generation, service life and maintenance needs, so a shared vocabulary is important for design, testing, manufacture and technical communication. This standard also provides short forms for some terms and word combinations, but only where they are unambiguous.

How the terminology is presented

The document gives definitions for many terms, while leaving self-explanatory expressions undefined. That structure is typical for a terminology standard: it helps different disciplines use the same concept consistently and reduces ambiguity in translation, documentation and specification writing.

In general technical context, friction is the resistance to relative motion between contacting surfaces, and wear is the progressive material loss caused by that contact over time. In plain-bearing applications, these phenomena are closely linked to material pairing, lubrication regime, surface roughness and operating conditions. The role of this publication is to standardise the vocabulary, not to set design requirements or performance limits.

• Common technical terms related to friction and wear
• Short forms available for some terms
• Abbreviated expressions allowed where unambiguous
• Self-explanatory terms presented without definitions
• A definition-based classification approach