Abstract
Accelerated tool wear and tool breakage are significant problems in micro-machining processes such as micro-milling. Traditional flood cooling processes are unsuitable for micromilling due to the excessive collision force between the fluid stream and the tool being large enough to affect the accuracy of the cutting process. In this research an atomization-based cooling and lubrication system is presented that delivers atomized cutting fluids to a micro-milling tool through the use of an original nozzle design based on two orthogonally-directed streams. The system and nozzle is used to investigate the relative importance of cooling and lubrication on micro-milling of 6061 T6 cold-rolled aluminum with a 0.508 mm diameter two-fluted end mill. Six cutting conditions are experimentally evaluated based on cutting forces and tool life. Lubrication is investigated through two concentrations (10% and 25%) of a semi-synthetic cutting fluid. Cooling is investigated through the use of atomized deionized water as well as dry cutting with cooling provided by a Ranque-Hilsch voitex tube. Dry cutting was used as a control. Statistical testing revealed the importance of lubrication relative to cooling when machining on the micro-scale as deionized water performed the worst of all tests conducted. Based on the experimental results, recommendations are made for the design of future micromachining cooling and lubrication systems.