TAGUCHI-BASED OPTIMIZATION OF PLASMA CUTTING PARAMETERS OF LOW-CARBON STEEL FOR SURFACE ROUGHNESS AND HEAT-AFFECTED ZONE CHARACTERISTICS

Abstract

Plasma arc cutting is a non-conventional manufacturing process widely used in the mechanical industry. In this process, material removal is achieved through localized melting under the action of the high-temperature plasma jet. The cut quality is primarily influenced by the operating parameters of the cutting process, which necessitates their accurate adjustment. Furthermore, the mechanical and metallurgical properties of the Heat-Affected Zone (HAZ) can also have an effect on the quality of this surface. However, previous research often neglects to study the link between technological parameters, cut quality, and the properties of the Heat-Affected Zone (HAZ). To fill this gap, this study aims to optimize the process parameters of plasma cutting, such as the cutting speed, current intensity, and standoff distance, of a 4 mm thick mild steel sheet in order to minimize the cut surface roughness. We also seek to establish the link between the optimal conditions and the phase transformations generated in the Heat-Affected Zone (HAZ). This provides a global overview of the relationship between the process parameters, the cut quality (particularly surface roughness), and the HAZ characteristics. To achieve this objective, the Taguchi method was employed using the Signal-to-Noise Ratio (S/N). This approach allowed for the determination of the optimal configuration for a minimal surface roughness. Analysis of Variance (ANOVA) revealed that cutting speed is the most influential factor on roughness, contributing to 43.7% of the response variation, followed by current intensity (20%) and the standoff distance (3.3%).