Experimental Investigation of surface roughness in dry turning of AISI 4340 alloy steel using PVD- and CVD- coated carbide inserts

The performance of coated inserts was described using Response Surface Methodology (RSM) when turning AISI 4340 alloy steel using single layer PVD and triple layer CVD coated inserts. Cutting tests were performed under dry cutting conditions so as to reduce the effects of cooling agents on the environment. Surface roughness (Ra) was the main response variable investigated. The experimental plan was based on the face centered, central composite design (CCD). The experimental results indicated that the proposed mathematical model suggested could adequately describe the performance indicators. Feed is the most significant factor affecting the surface roughness one followed by cutting speed. RAMP function plots and 3-D graphs shows the comparative effects of both the coatings of inserts on the work-piece surface roughness