## 4 Conclusions  
VPP techniques are pivotal in advancing additive manufacturing (AM), with their research crucial for enhancing products across various sectors, particularly in medical and  
Figure 13: Pyramidal specimens.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**Manufacturing Technology**} \\ \cline{2-5}  & \multicolumn{2}{c}{**LCD**} & \multicolumn{2}{c}{**DLP**} \\ \hline \multirow{2}{*}{**Geometry**} & \multirow{2}{*}{**Average (\(\upmu\)m)**} & **Standard** & \multirow{2}{*}{**Average (\(\upmu\)m)**} & **Standard** \\  & & **Deviation (\(\upmu\)m)** & & **Deviation (\(\upmu\)m)** \\ \hline Cylinder & 180 & 7 & 176 & 10 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Experimental results for the height of pyramidal specimens.  
industrial fields. This study presents a geometrical analysis to examine the behaviour of LCD and DLP technologies. By analysing the geometrical aspects of both DLP and LCD methods, the impact of manufacturing parameters on the resulting features has been identified. Moreover, notable differences between these two technologies have been observed. The study also establishes optimal exposure times for each technology, based on the outcomes of various experiments. For LCD technology, the ideal exposure time is 8 s, which aligns with the default lamination program's recommendation. In contrast, DLP technology requires an optimal exposure time of 2.5 s, which is slightly longer than the manufacturer's suggestion of 2 s.  
The precision of each technology along the XY axis has been assessed as well. Regarding the minimum feature size that can be fabricated, DLP technology consistently outperforms LCD technology, achieving feature sizes as small as 200 \(\upmu\)m compared to LCD's 500 \(\upmu\)m. Additionally, DLP technology tends to produce features that are closer to the intended design values, especially in regards to smaller features, whereas LCD technology shows marginally better results in manufacturing larger parts. This enhanced precision in micro-feature fabrication using DLP may stem from the more intense light source used in DLP projectors compared to that used in LCD displays. However, LCD technology generally yields better visual quality in parts due to superior anti-aliasing systems that mitigate the staircase effect, which can distort the dimensions of features away from the design values. Geometrical analysis supports that features made with DLP are closer to design specifications compared to those made with LCD in micro-feature production. The study also explores the significance of the STL file resolution. It finds that for features smaller than 2 mm, the resolution of the STL file becomes less critical, whereas for larger features, the resolution of geometry discretization can significantly impact surface quality. A high-resolution STL file, when used for manufacturing larger parts, may significantly increase both processing time and file size. Finally, the accuracy of both technologies in the vertical axis was evaluated by measuring the heights of various pyramids, demonstrating that both technologies achieve similar accuracy in the Z-axis.  
Conceptualization, J.M.-J., J.M.V.-M. and M.B.; project administration, J.S. and J.M.V.-M.; experimental methodology, J.M.-J.; investigation, J.M.-J. and M.B.; data processing, J.M.-J. and M.B.; formal analysis, J.M.-J., J.M.V.-M. and M.B.; project review, J.S. and J.M.V.-M.; writing--original draft preparation, J.M.-J. and M.B.; writing--review and editing, J.S. and J.M.V.-M. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding authors.  
This work has been developed under the support of the Mechanical Engineering and Industrial Design Department and the Vice-Rector's Office for Scientific Policy of the University of Cadiz.  
The authors declare no conflicts of interest.