Surface Integrity In Thread Cutting On Titanium Alloys Ti6AL-4V under dry condition

Abstract

In this study, machining effect of variable parameters on surface integrity of titanium alloys (Ti6AL-4V) thread was analyzed. The cutting was performed in dry machining with PVD Aluminum Titanium Nitride (AlTiN) coated cutting insert. They were two condition of tool have been deployed in this study which were new and worn tool. Depth of cut and cutting speed were manipulated on both worn and new tool to obtained result variation that later will be used as comparison between new and worn tool effect to the surface integrity. Depth of cut variables was 0.2mm and 0.25 mm while, machining speed was 35 m/min and 55 m/min. They are 8 pieces of specimen all together. The 4 pieces were cut by new tool and the remaining pieces were cut by worn tool. The manipulation of depth of cut and cutting speed on new tool produced damage know as feed mark on surface texture. Worn tool produced worse damages compare to new tool. The damages such as cavity, metal debris and cracking boundary can be clearly seen via microscope. The analysis through scanning electron reveals the microstructure alteration produced by variable cutting parameter. The alteration of microstructure either in compression or tension cutting force shows the present of residual stress. Residual stress encourages the formation of intergranular crack that usually the cause of thread failure. Higher stress produced by worn tool affect the metallurgical state of material that allowed the formation of compact microstructure zone beneath machined surface.