Investigating tool performance and wear when simulating bandsawing of nickel-based superalloy under interrupted orthogonal turning condition

The manufacturing industries still face the most challenging job at hand to machine nickel-based superalloy, Inconel 718, efficiently and economically. In contrast to the extensive research efforts in secondary machining processes such as turning, milling and drilling, very little or no attention is paid on bandsawing of Inconel 718. This article presents an experimental investigation of machining Inconel 718 using carbide-tipped bandsaw teeth in a custom-made experimental facility. Cutting forces were measured during the bandsawing operation using a dynamometer, and the wear modes and mechanisms in the bandsaw teeth were investigated in a scanning electron microscope. Three different feeds or depths of cut (10, 20 and 30 mu m) were employed with a cutting speed of 30 m/min during the machining tests. At smaller feed or depth of cut (10 mu m), abrasive wear, adhesive wear and some degree of plastic deformation were identified as the governing mechanisms of tool wear. The higher depth of cut (30 mu m) could cause cracking, chipping or premature failure of the carbide tip in bandsaw tooth. Strong welding of workpiece material to the cutting edge formed a built-up edge, which would impair the bandsawability due to the modification of the cutting edge. The higher depth of cut significantly improved the machining performance due to the reduction in specific cutting energy. However, it was not recommended to apply higher depth of cut as there were obvious possibilities of premature tooth failure. Machining force and specific cutting energy results along with chip characteristics were correlated with the tool performance and tool wear. The results of this investigation would be helpful for bandsaw manufacturers and end users to get a fundamental understanding of the bandsawability of Inconel 718 with the carbide-tipped bandsaw.