## 3 Results and Discussion  
### Effects of Infill Patterns on SR  
Weight measurement was conducted by Cura(r) software to examine differences between all samples. As shown in Table 5, the weight differences for patterns with the same density were \(\pm 1\) g accordingly. Designing the patterns to have better adhesion and avoid gaps was the vital section of this research. Thus, patterns were modeled to be close to patterns generated by the FDM 3D printer. Surface measurement was accomplished for all samples whereas before that the issues of surface and layer binding were examined to determine the effects of these two methods. All specimens' quality represented purity and clearness, however, defects were visible in the bottom layer in concentric samples generated by CAD. Figure 6 shows the issue in these two samples. The binding between layers was good but the initial layer (bottom layer) which was attached to the printing bed was not perfect, and the printed line was not attached properly. This issue was caused due to the poor temperature at the beginning of the process that led to weak bonding between some parts of the bottom layers. Table 6 illustrates the average SR for each sample. Surprisingly, the quality of patterns generated by CAD was slightly better than those generated by the FDM machine. However, for zigzag pattern samples, the value of average R\({}_{\text{a}}\) for generated FDM (2.94 \(\upmu\)m for 30% infill density and 3.45 \(\upmu\)m for 50%) was lower than CAD samples. This might cause the non-optimum design in pattern layers. In contrast, CAD samples showed better average R\({}_{\text{a}}\), and the surface texture was slightly superior compared to FDM parts. These results showed infill pattern and infill density affected texture and surface integrity. Meanwhile, the differences between CAD specimens are visible in Figures 7 and 8. The graphs were created in MATLAB(r) to clearly show the range of average waviness values (from 2 \(\upmu\)m to 7 \(\upmu\)m). As shown in Figure 8, the zigzag samples have the worst surface quality among samples while grid and concentric samples have the best surface texture in the CAD procedure. This poor quality in the triangle sample was due to the design and classified layers. On the other hand, Figure 7 shows the quality of each point for patterns generated \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Process \&** & **Concentric 20\%** & **Grid 30\%** & **Triangle 10\%** & **Zigzag 30\%** \\
**Pattern** & **Concentric 30\%** & **Grid 60\%** & **Triangle 40\%** & **Zigzag 50\%** \\ \hline CAD weight (gr) & 12 & 15 & 10 & 12 \\  & 15 & 18 & 15 & 17 \\ FDM weight (gr) & 12 & 14 & 12 & 14 \\  & 14 & 18 & 16 & 17 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Weight differences for CAD and FDM samples. Figure 6: Issues in concentric CAD specimens in bottom layer. by FDM machine. As can be seen, triangle patterns resulted in poor surface texture among other samples. This means that the value of \(\text{R}_{\text{a}}\) for each point was higher. The grid sample showed the best quality and the lowest average value among FDM printed samples, with 2.85 \(\upmu\)m and 2.67 \(\upmu\)m for 30% and 60%, respectively. The differences in SR were examined and results showed patterns generated by CAD parts were slightly better compared to the FDM machine. Also, grid samples had the best surface integrity compared to other specimens. The surface texture was almost the same and the value of average waviness in all specimens fluctuated in the same range.