A Study of Minimum Quantity Lubrication (MQL) by Nanofluids in Orbital Drilling and Tribological Testing

Mohsen Mosleh,Gary Lipczynski,Sonya Smith,John Belk,Khosro Shirvani

doi:10.3390/jmmp3010005

Abstract

In minimum quantity lubrication (MQL), an aerosol containing a minimum amount of the cutting fluid is delivered to the tool/workpiece interface during the metal cutting operation. The fluid lubrication by the fluid and the cooling by the compressed air in the aerosol improves the cutting process, while the low consumption rate in MQL provides less cleanup and reduces the associated cost. In this paper, molybdenum disulfide (MoS2) and hexagonal boron nitride (hBN) nanoparticles were added to the aerosol for providing a third functionality to the MQL, which is solid lubrication at the interface. Both orbital drilling and tribological testing using a four-ball tester were studied to examine the effectiveness of solid lubrication in MQL. In orbital drilling of titanium with tungsten carbide tools, MQL with nanofluids containing MoS2 nanoparticles resulted in less transfer film buildup on the tool. In four-ball testing, MQL with nanofluids with MoS2 and hBN nanoparticles yielded lower surface temperatures and less variation of frictional torques in titanium.

Highlights

In the context of cooling and lubrication by cutting fluids, the notion of “the more, the better” is giving way to stricter environmental regulations and research findings in recent years in the effectiveness of minimum quantity lubrication (MQL) in lieu of flood lubrication
This paper presents the results of an investigation on the three functionalities of MQL by nanofluids, i.e., fluid lubrication, cooling, and solid lubrication, in orbital drilling and tribological testing at a flow rate of 2 mL/h, which is less than the flow rate in MQL with conventional fluids
Molybdenum disulfide (MoS2) nanoparticles dispersed in Boelube exhibited the ability to reduce the buildup of the Titanium 6Al4V (Ti) transfer film on WC tools in orbital drilling

Summary

Introduction

In the context of cooling and lubrication by cutting fluids, the notion of “the more, the better” is giving way to stricter environmental regulations and research findings in recent years in the effectiveness of minimum quantity lubrication (MQL) in lieu of flood lubrication. In MQL, a minute amount of the cutting fluid with an approximate flow rate range of 5–50 mL/h is mixed with compressed air and delivered as aerosol to the tool/workpiece interface [1]. In addition to economic efficiency and environmental compatibility, the MQL has been reported to meet or exceed flood lubrication performance in terms of tool life and surface quality of the workpiece [10]. In milling of high strength steel with cemented carbide tools and end milling of stainless steel using TiAlN coated nitride tools, MQL reduced the tool wear and surface roughness compared with dry and flood-lubricated cutting [11,12]

Methods

Results

Conclusion