Through-tool minimum quantity lubrication and effect on machinability

This paper simulated through-tool minimum quantity lubrication (MQL) to characterize micromist droplet size and distribution. The effect of nozzle surface roughness and air pressure was experimentally performed to study the lubricant droplet and its effectiveness in micromilling of Inconel alloy. The external MQL simulated internal flow in commercially available drill with internal cooling channels. Droplets were collected on a glass plate from which the average airborne diameters and standard deviation were calculated. The droplet diameter and distribution were most sensitive when using nozzle with rough internal surface. MQL at different conditions was used in micromilling of Inconel 718 blocks that were additively printed by selective laser melting technique. Micromist generated from a rough nozzle at 550 kPa effectively improved tool life and produced micromilled slots with surface finish Sa of 1.5 μm.