# Non-Cutting Moving Toolpath Optimization with Elitist Non-Dominated Sorting Genetic Algorithm-II
## 4 Simulation Results and Experimental Validations
### Analysis of the Impact of PP on the Machining Cycle Time in CNC Processes
#### 4.2.2 Experimental Results  
The pictures of workpieces during the manufacturing on the CNC machine are illustrated in Figure 10. Their machining cycle times during the manufacturing are compared in Table 6. It can be observed that, for Workpiece 1, the cycle time is reduced from 1692 s to 1573 s, saving approximately 119 s. This represents a significant improvement of approximately 7% in the machine cycle time, as provided in Figure 11.  
Additionally, the same procedures were applied to Workpiece 2, resulting in a similar reduction in the machine cycle time. The decrement for the optimized Workpiece 2 is 102 s. This represents a significant improvement of approximately 6.72% in the machine cycle time, as shown in Figure 12.  
As demonstrated in the experimental results of this study, the initial toolpaths contained unnecessary turns and extended distances. To make these paths more efficient, the NSGA-II with an elitist strategy has been examined. The NSGA-II optimizes the trajectory through reducing travel distances and simplifying the path. Consequently, as shown in the second optimized set of figures, a smoother and more direct route is achieved. The optimization process involves defining the path as a sequence of points that should be  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Workpiece Versions** & **Cycle Time** \\ \hline Original Workpiece 1 & 1692 s \\ Optimized Workpiece 1 & 1573 s \\ Original Workpiece 2 & 1518 s \\ Optimized Workpiece 2 & 1416 s \\ \hline \hline \end{tabular}
\end{table}
Table 6: Experimental results of the machining cycle time for Workpiece 1 and Workpiece 2.  
Figure 10: The pictures of workpieces during the manufacturing on the CNC machine: (**a**) Workpiece 1 and (**b**) Workpiece 2.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Items** & **Specifications** & **Value** \\ \hline \multirow{3}{*}{Travel} & x-travel & 600 mm \\  & y-travel & 400 mm \\  & z-travel & 500 mm \\ \cline{1-1}  & Table size & 700 \(\times\) 420 mm \\ \cline{1-1}  & Speed & 8000 rpm \\ \cline{1-1}  & Max. Tapping Speed & 3000 rpm \\ \cline{1-1}  & Rapid Speed (G00) & 48/48/48 m/min \\ \cline{1-1}  & Cutting Feed Rate (G01) & 10,000 mm/min \\ \cline{1-1}  & x-axis & 1.5 kW \\ \cline{1-1} Motor & y-axis & 1.5 kW \\ \cline{1-1}  & z-axis & 3 kW \\ \cline{1-1}  & Spindle & 7.5 kW \\ \hline \hline \end{tabular}
\end{table}
Table 5: Parameters of the CNC machine used in the study.  
connected in the most efficient way possible, aiming to minimize the overall travel distance while complying with the operational constraints. The objective function used for this optimization included factors such as the Euclidean distance between consecutive points and the angular deviation at each point, which facilitated a smoother transition between line segments. The results are quantified through comparing the total path lengths before and after optimization and through observing a significant reduction in angular changes. This ensures that the tool moves efficiently between points by reducing the path complexity.