Workpiece surface integrity when milling Udimet 720 superalloy

The paper details a comprehensive investigation into the surface integrity of Udimet 720 following end milling under different environment conditions (dry, flood, higher pressure and MQL) and cutting speed (25 and 50m/min). Surface roughness (Ra) was < 0.25 mu m regardlss of tool condition with no white layers detected on any of the samples analysed. Residual stress measurements indicated surface compressive stress of 120 MPa on workpieces milled using new cutters under MQL environment. In contrast, worn tools produced surface tensile stresses of similar to 80 MPa, with subsurface compressive residual stress of up to similar to 400 MPa at a depth of 80 mu m. (C) 2016 The Authors. Published by Elsevier B.V.