Performance of carbide end mills coated with new generation nano-composite TiAlSiN in machining of austenitic stainless steel under near-dry (MQL) and flood cooling conditions

Abstract

In the present study, a new generation nano-composite TiAlSiN coating has been deposited on 2-fluted carbide end mills using High Power Impulse Magnetron Sputtering (HiPIMS) in quadra-cathode target configuration. A highly smooth coating of about 3 μm thickness was realized and coated tools were subject to high-speed milling of austenitic stainless steel, which is otherwise known to cause severe diffusive wear on uncoated carbide tools. The effectiveness of TiAlSiN coating has been investigated on austenitic stainless steel under dry, wet (flood, 25 l/h), and near-dry (MQL, 250 ml/h) conditions. TiAlSiN coated tools experienced severe diffusive adhesion of work material on its cutting edge during dry machining. The near-dry approach with a cutting fluid consumption rate of only 250 ml/h was found to be a more effective, and greener approach. There was no sign of delamination of the coating under dry, flood, and near-dry environments. A maximum of 20 % reduction in cutting force and 45 % reduction in roughness (Ra) have been recorded in a near-dry environment compared to a flood environment. Performance of the HiPIMS deposited TiAlSiN coated tools have also been compared with that of commercial TiAlN and commercial TiAlSiN tools (deposited by DC Magnetron Sputtering) and found to be potentially more effective in milling of SS304 steel.