OPTIMIZATION OF CUTTING PARAMETERS FOR SURFACE ROUGHNESS AND MICROSCOPY ANALYSIS IN MACHINING HARDENED HIGH THERMAL CONDUCTIVITY 150 (HTCS-150) STEEL

Mohd Fairuz Mohd Rashid; Mohd Hadzley  Abu Bakar; Mohd Fauzi  Mamat; Lailatul Harina Paijan; Nor Ana Rosli; Norfariza Ab Wahab; Safarudin Gazali Herawan

Mohd Fairuz Mohd Rashid Faculty of Industrial and Manufacturing Technology and Engineering Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya,76100 Durian Tunggal, Melaka, Malaysia.
Mohd Hadzley Abu Bakar Faculty of Industrial and Manufacturing Technology and Engineering Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya,76100 Durian Tunggal, Melaka, Malaysia.
Mohd Fauzi Mamat Faculty of Industrial and Manufacturing Technology and Engineering Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya,76100 Durian Tunggal, Melaka, Malaysia.
Lailatul Harina Paijan Faculty of Industrial and Manufacturing Technology and Engineering Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya,76100 Durian Tunggal, Melaka, Malaysia.
Nor Ana Rosli Faculty of Industrial and Manufacturing Technology and Engineering Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya,76100 Durian Tunggal, Melaka, Malaysia.
Norfariza Ab Wahab Faculty of Industrial and Manufacturing Technology and Engineering Universiti Teknikal Malaysia Melaka (UTeM), Hang Tuah Jaya,76100 Durian Tunggal, Melaka, Malaysia.
Safarudin Gazali Herawan Industrial Engineering Department, Faculty of Engineering, Bina Nusantara University, 11480, Jakarta, Indonesia.

Keywords: HTCS-150, optimization, surface integrity, surface roughness

Abstract

The machining of advanced alloys, such as High Thermal Conductivity Steel 150 (HTCS-150), is essential for manufacturing press hardening dies used in the automotive and metal stamping industries. Achieving the required surface finish on HTCS-150 poses challenges, often leading to surface defects like feed marks, scratches, and micro pits. This study focuses on optimizing machining parameters of HTCS-150 dies, including cutting speed, feed rate, and depth of cut. Controlled milling experiments using a carbide ball-end mill were conducted to optimize surface roughness by developing a Response Surface Methodology (RSM) model with a Box-Behnken design. Microscopy analysis further identified surface defects and provided deeper insights into the effects of machining parameters. The results show that the model developed with quadratic best fit and error percentage less than 10%. Depth of cut had the most significant impact on surface roughness, followed by feed rate and cutting speed. The optimal combinations of 125 m/min cutting speed, 0.30 mm/tooth feed rate, and 0.1 mm axial depth of cut, allow minimum surface roughness up to 0.22 µm. Smaller depths of cut produced finer finishes by minimising peak-valley gaps, while larger depths of cut increased roughness and introduced visible feed marks. Lower feed rates resulted in smoother profiles due to overlapping tool paths, whereas higher feed rates caused surface waviness and higher roughness. Lower cutting speeds created rough surfaces due to weak shearing forces, and higher speeds led to non-uniformity and increased roughness due to material deformation. These results provide a foundation for optimizing machining parameters to enhance surface quality, reduce defects, and improve process efficiency. The developed optimization model offers manufacturers a valuable tool for producing longer-lasting dies and higher-quality products.