## 2 Method and Materials
### Experimental Details  
The experiments have been planned with eight combinations of optimal control factors obtained from DE optimization of AISI grade steels, owing to the industry's cost constraints and practical feasibility. The experimental data for forming responses have been gathered with a minimum of five replicates in each combination for AISI 1010 steel, and the same have been represented in Table 5. The punches are manufactured accurately to a tolerance of 0.02 mm with high-speed steel material (S600 BOHLER grade) and heat-treated to 61-63 Rc. The billets were also machined with AISI 1010 steel material, annealed to 108 Hv, and coated with molybdenum disulfide. The punches and billets have been machined on a CNC turning center, and inspected with a micrometer and FARO ARM coordinate measuring machine to substantiate tolerances on GD&T parameters such as concentricity, perpendicularity, and cylindricity. Figure 5 shows the machining operations and inspection performed for the manufacture of punches and billets. The experiments were conducted on a close-frame 600 Ton hydraulic press (Chimaho automation systems).  
The billets, after annealing, have been lubricated with MoS\({}_{2}\) powder of 3 \(\upmu\)m particle size before placing them in the die cavity to facilitate better deformation. The punches are mounted onto the ram sequentially according to the experimentation order. A master pressure/force gauge of 400 kg/cm\({}^{2}\) capacity has been specifically designed and manufactured. The 250 mm dial size of the master gauge has been exclusively planned to capture the forces at higher resolution and to measure the force with a least count of 0.25% of a  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**SI. No.**} & **Reduction** & **Billet Size** & **Punch** & **Billet Size** & **Punch** & **Land** \\  & **Ratio (\(r\))** & **Ratio (\(z\))** & **Diameter** & **(mm)** & **Angle** & **Height** \\  & & & & **(d-mm)** & **(a-deg)** & **(h-mm)** \\ \hline
1 & 0.3 & 0.5 & 25 & \(\mathcal{O}30\times 15\) & 170 & 2.0 \\
2 & 0.3 & 0.7 & 25 & \(\mathcal{O}30\times 21\) & 170 & 2.0 \\
3 & 0.4 & 0.5 & 23 & \(\mathcal{O}30\times 15\) & 170 & 4.0 \\
4 & 0.4 & 0.8 & 23 & \(\mathcal{O}30\times 24\) & 170 & 2.6 \\full-scale division. The gauge had been connected and integrated with the press during experiments. A high-resolution imaging technique was employed to capture the needle deflection and the readings of the master gauge with a digital single-lens reflex camera (Nikon D5600 DSLR). The experimental process and gauge readings have been recorded, as shown in Figure 6a,b.  
The forged part has been sectioned in the transverse direction to obtain the metallographic examination possible in this section. The slit forged specimen surface is ground with SiC papers and polished with 1 \(\upmu\)m diamond paste. Figure 7 depicts the initial state of the raw material (billet), forged, and mid-sectioned parts. Micro-hardness values at cup thickness of the transverse sections of polished specimens have been obtained using a computerized micro Vickers hardness tester.  
Figure 5: Punches and billets preparation (Courtesy: KLE Technological University, Hubballi, India).  
Figure 6: (**a**) Close frame 600 Ton hydraulic press; (**b**) the master gauge and experimental set-up (Courtesy: S. S. Industries, Bangalore, India).