The Study to Optimum Parameters for Surface Roughness (Ra) Using Ballnose Cutting Tools in SKT4 Steel Forging

The objective of this research is to determine the appropriate parameters for achieving the desired surface roughness (Ra), cutting tools is used a hard series carbide ball-nose end mills (model 5R × 10 × 60L), equipment consists of a Chevalier automatic milling machine (model QP 2026-L) for the machining process and a calibrated Mitutoyo surface roughness tester (model SJ-310) for measuring the surface roughness. The surface roughness tester was calibrated using a 2.94 µm Mitutoyo calibration plate. The SKT4 steel sample is prepared with a size of 100 × 100 × 50 mm, hardness range of HRC 40-48. The research are focused on investigating the influence of the feed rate and depth of cut on surface roughness. The spindle speed was maintained at 1,500 RPM, and air cooling was utilized during the milling process. Surface roughness was evaluated using the Ra parameter, representing the average roughness of the surface. The measured Ra values were compared to a standard range of 12.5–3.2 µm. The results indicated that variations in the feed rate and depth of cut had a significant impact on surface roughness. Optimal surface roughness was observed at feed rates of 300, 500, 600, and 800 mm/min. Furthermore, a difference in the depth of cut of 4 conditions had a notable effect on surface roughness.