Productivity Enhancement of Twist Drill Bit by Molybdenum Trioxide (MoO3) Nano-Coatings and Cryo-Treatment

Abstract

Molybdenum trioxide nano-coatings are deposited on HSS twist drill bits under
constant flow of argon gas at a flow rate of 48 SCCM in the oxygen atmosphere at a working
pressure of 4.9x10-5
torr by a reactive dc magnetron sputtering technique to improve the
performance and lifetime of high-speed steel (HSS) drill bits. The X-ray reflectivity
measurements estimated thickness of the nano-coatings on the drill bits as around 100nm. A
significant improvement in productivity of the drill bits with MoO3 nano-coatings and
cryogenically treated nano-coated tools is found over uncoated drill bits. The tool life has been
enhanced by about 125% when MoO3 nano-coatings were made on HSS drill bits. Further an
increase of 10% in lifetime was observed when the nano-coated drill bit is cryo-treated with liquid
nitrogen immersion. SEM studies were also reported. The minimum surface roughness measured
as 6.83 µm for MoO3 coated HSS tools.