Surface Integrity in MQL Drilling Nickel-Based Superalloy
Nickel-based superalloys remain the most widely used of all materials in aerospace industry, contributed over 50 % of the weight of a jet engine. In machining of any jet engine components, it is necessary to satisfy the surface quality or surface integrity requirements to facilitate high reliability components. In the present study, surface integrity of Inconel 718 was studied when drilling under different lubricants. The holes were drilled individually using indexable AlTiN coated carbide drill under minimum quantity of lubricant (MQL) conditions. The results demonstrated that the machining conditions and lubricants strongly influence the surface integrity. The surface roughness decreases with the increase in cutting speed and increases with the increase in feed rate. Microhardness profiles indicated that the subsurface deformation extends up to a 100 and 150 μm for palm oil and synthetic ester, respectively underneath the machined surface. Pit holes, cavities, grooves, microcracks and surface smearing were the dominant surface damages criteria for all cases.
Jianhong Zhao, Masanori Kunieda, Guilin Yang and Xue-Ming Yuan
E. A. Rahim and H. Sasahara, "Surface Integrity in MQL Drilling Nickel-Based Superalloy", Key Engineering Materials, Vols. 447-448, pp. 811-815, 2010