The adhesive-cohesive property of a grease, i.e., how well a grease adheres to the surface that it lubricates. In the adhesive industry, tackiness was defined as the force applied to separate two solid surfaces joined by an adhesive layer in its liquid state. In the grease industry, tackiness is qualitatively considered as the ability of a grease to form threads as it is being pulled apart, e.g., when a small amount of grease is held between the thumb and forefinger of an operator, and the operator increases the gap between their thumb and forefinger. Research is underway to develop a formal definition and quantitative test method to measure tackiness and adhesion of grease.
Properties of lubricating greases that are observed visually when handling grease. Texture is described in the following terms:
Brittle – Has a tendency to rupture or crumble when compressed
Buttery – Separates in short peaks with no visible fibers.
Long Fibers – Shows tendency to stretch or string out into a single bundle of fibers.
Resilient- Capable of withstanding moderate compression without permanent deformation or rupture.
Short Fibers – Shows short break-off with evidence of fibers.
Stringy – Stretching into long fine threads, but with no visible evidence of fiber structure.
Tacky – Having adhesiveness, especially to metal surfaces. Greases containing polymers tend to be tacky.
Other terms, such as Smooth, Rough, Grainy, etc., are defined under Bulk Appearance.
The solid particles that are relatively uniformly dispersed in a liquid lubricant to form the structure of lubricating grease. The solid particles may be fibers, platelets, amorphous particles, or polymers.
Decrease in grease consistency (softening) as a result of shearing, followed by an increase in consistency (hardening) after shearing is stopped. (Thixotropic age hardening is a relatively prolonged process proportional to aging time and is seldom, if ever, complete. In contrast, the apparent viscosity increase in non-Newtonian systems with decreasing shear rate is instantaneous and fully reversible. Lubricating grease is both thixotropic and non-Newtonian.)
See OK Load
A synonym for translation or linear motion in DIN (Deutsches Institut für Normung e. V.) and other European specifications and standards.