Quantification of Tackiness of a Grease: The Road to a Method

Abstract

In this work, we report on the most recent progress in studying temperature influence on tackiness of greases, as well as the reproducibility of the method. Tackiness and adhesion of greases have been identified as key intrinsic properties that can influence their functionality and performance. During the last eight years, a reliable method to quantify the tackiness and adhesion of greases has evolved from an experimental lab-scale set-up towards a standardised approach, including an ASTM method and a dedicated test tool. The performance of lubricating greases—extensively used in diverse industrial applications—is strongly dependent on their adherence to the substrate, cohesion and thread formation or tackiness of the greases. This issue attracts more and more industrial interest as the complexity in grease formulation evolves and it is harder to differentiate between available greases. With this method, grease formulators will have an efficient measurement tool to support their work.

Assessment of the Lubricity of Grease‐Sealing Rotary Shaft Seals Based on Grease Properties

“…Achanta et al [21] define tackiness as ability to form strings or threads before separation. Georgiou et al [22] agree with that and differ between tackiness as ability to pull strings (according to the referenced ''finger test'') and adhesion as pull-off force to separate an indenter from grease. Achanta et al [21] measured the pull-off force using an approach-retraction test method with a ball on which a grease substrate is pressed.…”

“…When a specific load is reached, the substrate is removed from the ball, while the required normal force is measured. The approach of Georgiou et al [22] used a Falex tackiness adhesion analyser (TAA) to indent a 3-mm ball into a napkin filled with grease and subsequently retract it evaluating both, the pull-off force (as adhesion) and the thread formation (as tackiness). They found no correlation between adhesion and tackiness.…”

A review of advances in tribology in 2020–2021

“…On the other hand, the friction performance of greases is closely related to temperature. Georgiou et al [52] measured the adhesion and tackiness of greases with the indentation retraction approach and found that the ability of a grease to adhere to a surface (pull-off force) and to form threads when it is being pulled apart (tackiness) strongly depended on the temperature. Joysula et al [53] improved antiseizure and friction performance of grease without modifying the grease chemistry.…”

“…It is found that the distributions of the fluid pressure can be changed by Fig. 52 Traction curve comparison between simplified traction calculation and twin-disc measurements [854]. Reproduced with permission from Ref.…”

Influence of Rheological Properties of Lithium Greases on Operating Behavior in Oscillating Rolling Bearings at a Small Swivel Angle

“…It describes the ability of substances to form a bond with measurable strength between the contact partners at low contact pressure and short contact time [27]. In particular, the resistance of an adhesive substance to the separation of the bonded surfaces was examined [28].…”