Characterization and Performance of Minimum Quantity Lubricants in Through-Tool Drilling

Amla Patil,Tim Bangma,Obeidat Suleiman,David Stephenseon,Immanuel Edinbarough,Jay Raval,Wayne Np Hung,Bruce Tai

doi:10.26776/ijemm.05.04.2020.01

Abstract

This study characterized airborne microdroplet diameters and size distribution from two commercially available lubricants A and B for internal minimum quantity lubrication (MQL). The effects of air pressure, oil channel size, physical properties of lubricants on the resultant microdroplets and through-tool MQL drilling performance were studied. Airborne microdroplet diameters were highly sensitive to the coolant channel sizes and air pressure. Cluster method was used to divide microdroplets into smaller clusters for comparison. Experimental data show that the average airborne microdroplet of lubricant B was larger than that of lubricant A at different air pressures and channel sizes. The contact angle of lubricant A was at least 10° less than that of lubricant B when depositing on glass or aluminium. High-speed imaging showed the tendency of more viscous lubricant B sticking to the drill tip, and higher pressure and longer time was required to atomize this viscous oil. Built-up-edges were less significant when drilling A380 aluminium with lubricant A. Due to high machinability of A380 aluminium, variation of hole diameter and hole cylindricity were minimal when drilling with different lubricants. Insignificant improvement in hole quality was observed when drilling with excessive amount of MQL lubricants or high concentration of lubricant C in flood coolant.

Highlights

Minimum quantity lubrication (MQL) is an effective and environmentally friendly substitute to traditional flood cooling method, especially in high-aspect-ratio operation --such as gun drilling-- where cutting fluid delivery to the cutting edges is challenging
The topic of MQL has been investigated by many researchers, most of the published literature are for external MQL and very limited research papers were dedicated to internal or throughtool MQL
5 CONCLUSIONS AND RECOMMENDATIONS This study characterized two commercially available lubricants A and B for internal minimum quantity lubrication (MQL), and performed through-tool MQL drilling on A380 cast aluminium at fast production rate

Summary

Introduction

Minimum quantity lubrication (MQL) is an effective and environmentally friendly substitute to traditional flood cooling method, especially in high-aspect-ratio operation --such as gun drilling-- where cutting fluid delivery to the cutting edges is challenging. The topic of MQL has been investigated by many researchers, most of the published literature are for external MQL and very limited research papers were dedicated to internal or throughtool MQL. To understand how lubricant properties would affect performance of internal MQL, and possible benefits of high lubricant concentration in an aerosol mixture, this research study aimed to:. (i) Characterize and compare through-tool MQL microdroplets of two commercially available lubricants (ii) Study microdroplet formation and flow exiting from through-tool coolant holes of a twist drill (iii) Verify the internal MQL effectiveness with drilling experiments

Objectives

Methods

Results

Conclusion