# Capabilities and Limitations of Using Desktop 3-D Printers in the Laser Sintering Process
## 3 Results and Discussion
### Surface Roughness  
The surface roughness is not only influenced by the orientation of the structure [32], but also by the processing parameters [33] and the batch material. Considering the various machines, with significant differences in their construction, it was expected to find divergence between the produced samples. Table 6 shows the sample's surface roughness is dependent on the used machine and the build orientation of the tested surface.  
The best surface roughness was achieved for PA12 Smooth, on which nonmelted powder, which was attached to the model, was at least visible to the unaided eye. The mentioned samples were produced using Lisa with the laser source mounted on the XY kinematics, which does not allow  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Material** & **Surface** & **Ra [\(\upmu\)m]** & **Rz [\(\upmu\)m]** & **Rt [\(\upmu\)m]** \\ \hline \multirow{4}{*}{PA2200 (Formiga P110)} & top & 18.1 & 205.4 & 235.4 \\ \cline{2-5}  & bottom & 17.06 & 196.6 & 222.5 \\ \cline{2-5}  & side & 17.59 & 187.5 & 226.3 \\ \hline \multirow{4}{*}{PA12 Smooth (Lisa)} & top & 18.44 & 188.2 & 213.2 \\ \cline{2-5}  & bottom & 16.90 & 178.5 & 201.6 \\ \cline{2-5}  & side & 16.27 & 181.2 & 202.0 \\ \hline \multirow{4}{*}{PA12 Black (S1)} & top & 24.97 & 233.0 & 261.3 \\ \cline{2-5}  & bottom & 22.85 & 210.9 & 230.6 \\ \cline{1-1} \cline{2-5}  & side & 26.79 & 222.9 & 247.5 \\ \hline \hline \end{tabular}  
* The underline shows the lowest value on each sample group.  
\end{table}
Table 6: Average Surface Roughness of the Measured Samples.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & & & & & **Prodways \(|\) PAI2-L** \\  & EOS [ PA2200 & 3D Systems ] & **DuraForm ProX PA** & **1600 and Farsoon Technologies ]  FS \\
**Company/Material/System** & & & & **3300 PA** \\ \cline{2-5}  & **Formiga P110 by WUST [\({}^{\text{\tiny{40}}}\)]** & **Unknown Systems by EOS (\({}^{\text{\tiny{20}}}\))** & **ProX500 by WUST** & **Unknown Systems by 3D Systems (\({}^{\text{\tiny{20}}}\))** & **Unknown Systems by Prodways and Farsoon Tech. [\({}^{\text{\tiny{20}}}\)]** \\ \hline
**Tensile Modulus [MPa]** & & & & & \\ \hline X Direction & 1920.0 (32.8) & 1800 & 1834.0 (50.2) & & \\ \hline Y Direction & 1992.3 (22.5) & 1800 & 1781.7 (54.9) & 1770 & 1602 \\ \hline Z Direction & 1957.2 (22.8) & 1750 & 1839.8 (45.4) & & \\ \hline
**Tensile Strength [MPa]** & & & & & \\ \hline X Direction & 50.6 (1.3) & 52 & 47.9 (0.8) & & \\ \hline Y Direction & 52.9 (1.4) & 52 & 47.6 (1.6) & 50 & 46 \\ \hline Z Direction & 52.2 (1.3) & 52 & 45.9 (2.1) & & \\ \hline
**Strain at break [\%]** & & & & & \\ \hline X Direction & 24.6 (1.4) & 20 & 22.7 (2.2) & & \\ \hline Y Direction & 24.6 (1.4) & 20 & 22.2 (2.8) & 22 & 36 \\ \hline Z Direction & 15.2 (1.3) & 7 & 10.2 (4.3) & & \\ \hline \hline \end{tabular}  
* Wroclaw University of Science and Technology; \({}^{\text{\tiny{(1)}}}\) Present work in manuscript; \({}^{\text{\tiny{(2)}}}\) Values according to corresponding manufacturers’ data sheet.  
\end{table}
Table 5: Comparison of Mechanical Properties of PA 12 Manufactured in Different Industrial LS Systems.  
high scanning speeds when compared to systems that use galvanometers. The relatively long laser acquisition time enabled the best melting performance of a model--powder cake border.