Experimental investigation of hot machining process of high manganese steel using SNMG carbide inserts by design of experiments using taguchi method

Abstract

In the modern world, there is a need of materials with very high hardness and shear strength in order to satisfy industrial requirements. So many materials which satisfy the properties are manufactured. Machining of such materials with conventional method of machining was proved to be very costly as these materials greatly affect the tool life. So to decrease tool wear, power consumed and increase surface finish Hot Machining can be used. Here the temperature of the work piece is raised to several hundred or even thousand degree Celsius above ambient, so as to reduce the shear strength of the material. Various heating method has been attempted, for example, bulk heating using furnace, area heating using torch flame, plasma arc heating, induction heating and electric current resistance heating at tool-work interface. From the past experiments it was found the power consumed during turning operations is primarily due to shearing of the material and plastic deformation of the metal removed. Since both the shear strength and hardness values of engineering materials decrease with temperature, it was thus postulated that an increase in work piece temperature would reduce the amount of power consumed for machining and eventually increase tool life. The experiment is conducted in an auto feed lathe. The temperature is controlled by a thermocouple and automated flame heating system. The statistical analysis is done by Taguchi method. Taguchi designs provide a powerful and efficient method for designing products that operate consistently and optimally over a variety of conditions. The primary goal is to find factor settings that minimize response variation, while adjusting (or keeping) the process on target. A process designed with this goal will produce more consistent output. A product designed with this goal will deliver more consistent performance regardless of the environment in which it is used. Taguchi method advocates the use of orthogonal array designs to assign the factors chosen for the experiment. The most commonly used orthogonal array designs are L8, L16, L9 (i.e. eight experimental trials), L16 and L18. The power of the Taguchi method is that it integrates statistical methods into the engineering process. The significance of the control factors are found in the following order. Cutting speed - 150 rev/min, Depth of Cut - 0.5 mm, Temperature - 600 degree, Feed - 0.05 mm/rev From statistical design of experiments by Taguchi method (MINITAB software) and Hot Machining we find that the power required is decreased and the tool life is increased by 14.8 %.