Experimental investigation of different unconventional machined surface on hardox steel

Abstract

Machinability and surface behaviours are playing an essential role in metal forming and manufacturing processes. Hardox 500 steel is machined by ultrasonic machining (USM) and spark erosion machining (SEM) processes. The different input factors are used in both the processes and evaluate the rate of metal removal. Current, voltage and pulse duration are the control factors for spark erosion. Power rating, slurry concentration and grit size are the control factor for USM. Scanning force microscopy (SFM) is used to investigate the surface topography of the hardox steel. The effect of input constrains on rate of metal removal (RMR) is validated by variance analysis. In SEM process, current was the most effective factor on rate of metal removal and it’s provided the maximum contribution (79.75%) than other factors such as pulse duration (16.73%) and voltage (3.43%). In USM process, slurry concentration was the most effective factor on rate of metal removal and it’s provided the maximum contribution (83.78%) than other factors. The contribution effect of grit size and power rating is 13.15% and 2.53% respectively. Based on surface plot analysis, the machined surface of SEM is better than USM surface.