Machinability Improvement for Stainless Steel AISI 304 in Turning by Applying Magnetically Damped Cutting

Abstract

Stainless steels resistance to corrosion and staining, low maintenance and familiar luster make it an ideal material for many applications. The alloy is used in cookware, cutlery, household hardware, surgical instruments, major appliances, industrial equipment (for example, in sugar refineries) and as an automotive and aerospace structural alloy and construction material in large buildings. However, machining of this material is difficult due to high cutting force, lower tool life and high intensity of chatter related to its serrated chip formation behavior. An attempt to reduce chatter and thereby increase the tool life and surface finish by employing magnetic field during turning of the material has been made. A special fixture was designed and used to mount the permanent magnet with high power of 4500 Gauss at the bottom of the cutting tool. An accelerometer was attached at the bottom of the tool holder of 120 mm overhang and connected to the vibration data acquisition system. The vibration amplitude data were recorded at in the frequency range of 0 to 5 kHz. The recorded vibration signals were analyzed using DasyLab software (version 6). Response surface methodology (RSM) was employed in developing the chatter acceleration amplitude models in relation to primary cutting parameters: cutting speed, feed, and depth of cut. Design-expert software was applied to develop the second-order models for the two peak amplitudes observed at approximately at 1 kHz and 5 kHz and to develop the contours. The adequacy of the predictive models was verified using analysis of variance (ANOVA) at 95% confidence level.