# Characterization of Deburring by Abrasive Flow Machining for AL6061
## 3 Preliminary Testing
### 200 km Flow Length Test and Results  
For investigating the effects of flow speed and flow length on deburring, the flow length (L) was fixed at 200 km and the 43.8 poise medium was used. The progress of deburring was recorded at every 50 km of flow length. Figure 6 shows the deburred edges at the flow speed of 7.8 m/s. The dotted lines represent the burr-free boundaries \({}^{\text{O}}\)\(\mathrm{s}\) of the specimen before deburring. It is evident that the flow length has a significant effect on edge erosion. Moreover, the erosion exceeded far beyond deburring at the flow length of 50 km.  
Figure 7 depicts the burr edge erosion at various flow speeds for 200 km of flow length. The effect of flow speed on edge erosion was significant.  
The extent of deburring can be represented by the volume of material removed from the burr edge. Along this line, the reduction in the cross-sectional area of the burr edge can be identified as the deburred area. In Table 2, the observed deburred areas have been listed for different combinations of flow length and flow speed. Figure 8 indicates the graphical representation of Table 2.  
Figure 6: Progress of burr edge erosion for the flow speed of V = 7.8 m/s at every 50 km of flow length: (**a**) 0 km; (**b**) 50 km; (**c**) 100 km; (**d**) 150 km; (**e**) 200 km.  
Figure 7: Progress of burr edge erosion for the flow length of 200 km at various flow speeds, V = (**a**) 3.3 m/s; (**b**) 4.5 m/s; (**c**) 5.6 m/s; (**d**) 6.7 m/s; (**e**) 7.8 m/s.  
To observe the progress of deburring, the predicted flow lengths for C0.2 were uniformly divided into three steps, and the remaining flow lengths for C0.3 were again divided into three additional steps. For example, for the flow speed of 3.3 m/s, the predicted flow length for C0.2 was 83 km. The predicted six steps of flow lengths for the C0.2 and C0.3 chamfer conditions are listed in Table 4 at each flow speed.  
Figure 10 shows the progress of burr edge erosion in six steps at the flow speed of 7.8 m/s. The chamfered and smoothed edges corresponding to C0.2 and C0.3 are shown in Figure 11.  
Figure 12 shows the deburred edge profiles at the final step for each flow speed. An approximate of C0.3 condition was achieved for all the speeds.  
The deburred areas measured for each step at different flow speeds are listed in Table 5. Figure 13 shows a graphical representation of the data in Table 5.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Step** & **3.3 m/s** & **4.5 m/s** & **5.6 m/s** & **6.7 m/s** & **7.8 m/s** \\ \hline
1 & 28 km & 8 km & 5 km & 2 km & 1 km \\
2 & 56 km & 16 km & 10 km & 4 km & 2 km \\
3 & 83 km & 23 km & 16 km & 6 km & 3 km \\
4 & 120 km & 32 km & 22 km & 8 km & 4 km \\
5 & 157 km & 41 km & 28 km & 10 km & 5 km \\
6 & 194 km & 50 km & 34 km & 13 km & 7 km \\ \hline \end{tabular}
\end{table}
Table 4: Six steps of flow lengths leading to C0.2 and C0.3 chamfers at various flow speeds.  
Figure 10: Progress of burr edge erosion in six steps (Table 4) at the flow speed of 7.8 m/s: (**a**) 1 st step; (**b**) 2 nd step; (**c**) 3 rd step corresponding to C0.2; (**d**) 4 th step; (**e**) 5 th step; (**f**) 6 th step corresponding to C0.3.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Speed** & **Chamfer** & **C0.2** & **C0.3** \\ \hline
3.3 m/s & 83 km & 194 km \\
4.5 m/s & 23 km & 50 km \\
5.6 m/s & 16 km & 34 km \\
6.7 m/s & 6 km & 13 km \\
7.8 m/s & 3 km & 7 km \\ \hline \end{tabular}
\end{table}
Table 3: Predicted flow lengths for C0.2 and C0.3 chamfers at different speeds.