Examining the effects of cooling/lubricating conditions on tool wear in milling Hastelloy X

High tool wear rates serve as a leading factor that limits the machinability of nickel-based alloys. The high strength and corrosion/creep-resistant properties that make these materials attractive to the designer also make them challenging to machine by causing increased cutting edge temperatures and decreased tool life. This paper details the wear mechanisms and tool life when milling Hastelloy X using both cryogenic C02 and minimum quantity lubrication (MQL) as cooling/lubricating solutions. Experiments were conducted using a physical vapor deposition (PVD) TiAIN coated carbide bull nose cutter. Cutting forces were used in conjunction with microscope and thermal images to compare the performance of the two approaches. Results showed that MQL methods produced a predictable mode of tool failure, while cryogenic cooling significantly reduced the tool life and resulted in catastrophic failure modes.