Drop-on-Demand Printing as Novel Method of Oil Supply in Elastohydrodynamic Lubrication

W M Van Der Kruk,X M Li,T J Segers,C H Venner,S A Smit

doi:10.1007/s11249-019-1208-1

W M Van Der Kruk, X M Li + Show 3 more

Open Access

https://doi.org/10.1007/s11249-019-1208-1

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Abstract

The feasibility of drop-on-demand printing as a novel method for oil supply in elastohydrodynamic lubrication was tested for a single ball-on-disk contact to allow precise lubrication control at a minimal level of lubricant. It is shown that it is feasible to jet droplets of 3.3 pL for an oil of 46 mPa s viscosity at a controlled frequency which, for the conditions considered, results in droplets on the surface with a radius significantly smaller than the Hertzian contact radius. Experimental results of the film thickness evolution over time are presented from dry contact to fully flooded contact with different supply frequencies and a total oil usage of approximately 40 nL. By means of numerical simulation, the details of droplet ingestion into the contact are illustrated. It is shown that the central film thickness over time can accurately be predicted. The theoretical and experimental results provide a very strong incentive for further investigation of drop-on-demand printing as method to achieve optimal (re)lubrication at minimum level in the realistic setting of a rolling bearing.

Highlights

To mitigate the possible consequences of climate change, an unprecedented effort is required to change energy generation, energy usage, and all related technological processes toward a long-term sustainable development
Higher temperatures and higher loads lead to thinner lubricant films with increasing sensitivity to effects of surface roughness, dynamic loading and pressure disturbances resulting from subsurface material heterogeneity
The successful single contact results presented in this paper demonstrate that drop-on-demand printing is a very interesting technique to further investigate, e.g., in an experimental setup with an actual rolling bearing

Summary

Introduction

To mitigate the possible consequences of climate change, an unprecedented effort is required to change energy generation, energy usage, and all related technological processes toward a long-term sustainable development. This awareness has already led to restrictive bounds set on product development, and is affecting all areas of technology. Improved control of friction at a lower level by optimizing lubrication in machine components such as bearings and gears is a potential energy saver. This is a major challenge since the conditions at which lubricated contacts have to operate reliably are becoming more severe. In fully flooded EHL contacts, over 90% of the lubricant

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