Influence of helix angle on tool performances of TiAlN- and DLC-coated carbide end mills for dry side milling of stainless steel

This work reports the influences of helix angle on tool performances of titanium aluminum nitride (TiAlN)- and diamond-like carbon (DLC)-coated carbide end mills for dry side milling of 304L stainless steel. The study results revealed that the number of axis contact points and effective cutting length increased with increasing helix angle, leading to less tool wear and thinner milled chips but higher workpiece temperature. In addition, DLC-coated tools exhibited relatively high workpiece temperature, rapid chipping wear due to thermally induced graphitization, and chip-built-up on side edge while TiAlN-coated end mills displayed less severe abrasive wear on cutting and side edges. Moreover, the DLC-coated end mill with a high helix angle of 60A degrees gave the lowest surface roughness of 0.26 mu m within the cutting length of 20 m while the corresponding TiAlN-coated tools offered longer tool cutting length of more than 50 m with comparable surface finish. Consequently, the TiAlN-coated end mill with a high helix angle of 60A degrees offered high-quality surface finish with long tool life time and would be more useful for dry milling of stainless steels.