## 3 Results and Discussion
### Cutting-Path Planning in Five-Axis CAM of Stents and Actual Stent Machining
#### 3.3.3 Stent Arc Homogeneity  
The homogeneity of stent arcs was analyzed using the round corner depth of cut and errors with and without compensation, as shown in Table 2. A target round corner depth of cut of 0.1 mm was set as the baseline to observe and measure the depths of cuts on the arcs of the cut stent structures. The results revealed that the mean depth of cut of the arc without compensation was 0.074 mm, and the error variation at the nine positions was 0.044 mm (maximum = 0.046 mm and minimum = 0.002 mm). It was considered that the variation of the arc depth of cut was caused by center-of-rotation errors. To validate the cause, the errors obtained in the experiment were used. The actual arc depths of cut with compensation were compared with the target arc height values. The variation in depth of cut at the nine positions was 6 \(\upmu\)m (maximum = 0.027 mm, minimum = 0.021 mm), which was then compared with the variation in arc depth of cut without compensation (0.044 mm). The comparison results revealed that the homogeneity improved by approximately 86% with compensation. This suggested that, during machining without compensation, the distance of cutting track deviation was the center-of-rotation error, and the round corner arc homogeneity is highly correlated with center-of-rotation errors. However, the experimental results with compensation revealed that the mean actual arc depth of cut was approximately 0.075 mm, shorter than the theoretical value 0.1 mm.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Position** & **Width** & **Section Width** & **Section Width Errors** & **Section Width** & **Section Width Errors** \\ (No.) & **(Theoretical Value)** & **without Compensation** & **without Compensation** & **with Compensation** & **with Compensation** \\ \hline
1 & 0.3 & 0.301 & 0.001 & 0.301 & 0.001 \\
2 & 0.3 & 0.301 & 0.001 & 0.306 & 0.006 \\
3 & 0.3 & 0.305 & 0.005 & 0.301 & 0.001 \\
4 & 0.3 & 0.305 & 0.005 & 0.304 & 0.004 \\
5 & 0.3 & 0.312 & 0.012 & 0.308 & 0.008 \\
6 & 0.3 & 0.313 & 0.013 & 0.309 & 0.009 \\
7 & 0.3 & 0.303 & 0.003 & 0.298 & 0.002 \\
8 & 0.3 & 0.307 & 0.007 & 0.301 & 0.001 \\
9 & 0.3 & 0.303 & 0.003 & 0.302 & 0.002 \\ \hline \hline \end{tabular}  
Unit: mm.  
\end{table}
Table 1: Cross-section width errors of the stent with and without compensation.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Position** & **Arc Depth** & **Arc Depth without** & **Arc Depth Errors** & **Arc Depth with** & **Arc Depth Errors** \\ (No.) & **(Theoretical Value) A** & **Compensation B** & **A–B** & **Compensation D** & **A–D** \\ \hline
1 & 0.1 & 0.106 & 0.006 & 0.077 & 0.023 \\
2 & 0.1 & 0.063 & 0.037 & 0.074 & 0.026 \\
3 & 0.1 & 0.055 & 0.045 & 0.076 & 0.024 \\
4 & 0.1 & 0.098 & 0.002 & 0.075 & 0.025 \\
5 & 0.1 & 0.059 & 0.041 & 0.073 & 0.027 \\
6 & 0.1 & 0.064 & 0.036 & 0.076 & 0.024 \\
7 & 0.1 & 0.104 & 0.004 & 0.079 & 0.021 \\
8 & 0.1 & 0.063 & 0.037 & 0.074 & 0.026 \\
9 & 0.1 & 0.054 & 0.046 & 0.074 & 0.026 \\ \hline \hline \end{tabular}  
Unit: mm.  
\end{table}
Table 2: Round corner depth of cut and errors with and without compensation.