Abstract:
Various machining conditions are utilized to improve the machinability of metals. However,
some materials, such as EN C60 carbon steel, are challenging to process conventionally due to
their inherent properties. EN C60 is valued for its corrosion resistance and durability under
high pressures and temperatures, but its hardness makes it difficult to machine. This study
employed a hot machining process to enhance machinability.
EN C60 carbon steel and a CNMG120408-BM coated carbide were used as the workpiece and
cutting tool. The workpiece was heated in an MR 260E muffle furnace. Experimental
parameters included cutting speeds (70, 90, and 110 m/min), feed rates (0.04, 0.08, and 0.12
mm/rev), and temperatures (200°C, 300°C, and 400°C), with a constant depth of cut of 0.50
mm. Taguchi L9 and L27 orthogonal array designs were employed.
Responses measured were surface roughness (Ra), material removal rate (MRR), and tool wear
using a digital surface roughness tester (VOGEL), a scanning electron microscope (SEM), a
digital weight balance, and an analog caliper. Analysis was conducted using Minitab 19
software. Results indicated a high cutting speed of 110 m/min, a low feed rate of 0.04 mm/rev,
and a cutting temperature of 200°C produced a better surface finish.
Tool wear was higher at cutting speeds of 110 and 70 m/min and a feed rate of 0.12 mm/rev
during dry machining compared to hot machining. The highest MRR was achieved at 110 m/min
and 0.12 mm/rev, while surface roughness was minimized at low cutting speeds. The chip
morphology studied also revealed that at 110.00 m/min cutting speed, 0.04 mm/rev feed rate,
and 200°C temperature, the chip thickness was reduced by 16.00% compared to 110.00 m/min
cutting speed, 0.04 mm/rev feed rate, and 400°C temperature. A regression-based surface
roughness model was developed and found to be adequate, with an R² value of 99.11%
