Schmierkreis

Schmierkreis is a term found in some German-language technical texts, but it does not correspond to a single, universally defined concept in established science. The name literally means “grease circle,” and its precise meaning is highly context-dependent, varying with the author and field of use. In many references it is used informally to describe a circular region related to lubrication, coating, or smear phenomena, rather than a formal mathematical object.

In lubrication engineering and tribology, Schmierkreis is sometimes described as the circular zone around a lubrication point where a lubricant film or trail is expected to extend under operating conditions. The interpretation can depend on factors such as viscosity, rotation speed, load, surface geometry, and clearance, and no standardized radius or boundary is universally adopted.

In materials science or microscopy contexts, the term has occasionally appeared to denote a circular smear or deposit produced during sample handling, staining, or coating processes. Again, its definition is not fixed and relies on the specific procedure and reporting standards of the source.

Etymology and usage notes: Schmierkreis derives from Schmier (grease) and Kreis (circle). Because it is not a formal term in most disciplines, readers should look to the particular source for a precise definition or measurement method when encountering the expression.

See also: Circle, Lubrication, Film thickness, Smear test. References are limited to niche or historical texts where the term appears.