Establishing Core Hardness by Induction Hardening Process for Crankshaft

The main purpose of this paper is to identify the need for Surface Hardening in Crankshafts and establishing Induction Hardening as the most practically viable process for the same. Crankshaft is one of the largest components in the internal combustion engine that has a complex geometry consisting of cylinders as bearings and plates as the crank webs. Geometry section changes in the crankshaft cause stress concentration at fillet areas where bearings are connected to the crank webs. In addition, this component experiences both torsional and bending load during its service life. The crankshaft must be capable of withstanding the intermittent variable loads impressed on it. The principal purpose of Surface Hardening is to increase the hardness, wear resistance and endurance limit of the surfaces of metal components. The core remains tough and can withstand impact loads. Prior to the advent of Induction Hardening methods such as furnace hardening, flame hardening and liquid nitriding were used. However each of these processes presented problems such as inadequate or non-uniform hardening and distortion. Induction Hardening overcomes many of these problems through rotation of the part during heat-treating and selection of frequency and power to obtain adequate case depth and uniform hardness.