Variasi Sudut Potong Utama (Kr) Untuk Mendapatkan Nilai Kekasaran Permukaan Pada Pemotongan Paduan Aluminium 6061 Menggunakan Pahat High Speed Steel Pada Pembubutan Kering

This study aims to analyze the effect of the tool cutting-edge angle (Kr) variation on surface roughness, cutting temperature, and tool wear in dry turning of Aluminum 6061 alloy using High Speed Steel (HSS) tools. The experiment was conducted on a conventional lathe with three cutting-edge angle variations 80°, 70°, and 60° while other cutting parameters (feed rate, depth of cut, spindle speed) were held constant. Each variation was repeated 19 times, totaling 57 trials. Surface roughness was measured using a surface roughness tester, temperature with an infrared thermometer, and tool wear was observed using a digital microscope. The results show that surface roughness (Ra) decreased as the cutting-edge angle decreased: Kr 60° produced the lowest Ra of 1.855 µm (class N7), Kr 70° yielded 3.212 µm (class N8), and Kr 80° gave the highest value of 4.032 µm (class N8-N9). A One-Way ANOVA confirmed the difference was statistically significant (F = 52.454 > F table = 3.168; p = 2.21×10⁻¹³). The cutting-edge angle also influenced the type and severity of tool wear, while its effect on cutting temperature was not significant. A cutting-edge angle of 60° proved optimal for surface quality and tool life.