# Case Study: 3D Modelling and Printing of a Plastic Respirator in Laboratory Conditions
## 3 Description of the 3D Printing Procedure of the Selected Object
\begin{table}
\begin{tabular}{c c} \hline
**ZMorph VX** \\ \hline dimensions & \(530\times 555\times 480\) mm \\ \hline weight & 14 kg \\ \hline software & Voxelizer 2.0.0 \\ \hline print area size & \(235\times 250\times 165\) mm \\ \hline possibility of connection & USB, SD, Ethernet \\ \hline printing on material & ABS, PLA, PET, ASA, HIPS, TPU \\ \hline print about layer strength & 1.75–3 mm \\ \hline price & \(5374.82\copy\) \\ \hline \end{tabular}
\end{table} 
Table 2: Basic specifications of the 3D printer ZMorph VX. _Print a Respiratory on a ZMorph Printer_  
The ABS/Acrylonitrile butadiene styrene was chosen to produce the respirator. Visible and unrecognizable from PLA/polylactide strings, ABS plastic has been used in automotive manufacturing for years, as it demonstrates resistance to oils, acids, and moisture. Its thermal stability is satisfactory. It does not have an exact melting point; it is around 180 \({}^{\circ}\)C. The disadvantage is the relatively high temperature for solidification of the material, which is about 100 \({}^{\circ}\)C. There is a high risk of material loss during the cooling process. This can result in a loss of up to 0.8% of the total volume. As a result, significant deformations of the model (e.g., twisting of the first layers) can occur until the model itself cracks. This problem can be solved by choosing a printer. This is ideal if the printer has a heated work platform. The ideal temperature of this pad is between 100 and 130 \({}^{\circ}\)C. You also need to focus on the printing process itself. Caution is required when heating the plastic, releasing acrylonitrile (a toxic compound) fumes, which can result in severe mucosal irritation. Due to the ability of ABS to have good solubility in acetone, it is possible to produce large models and then glue them. After selecting the printer, material, and model design, it is necessary to transfer the STL models to the software and create the appropriate G-codes. After adding G-codes, there were two options for data transfer, either directly to the printer or using an SD card. Specifically, for the Zmorph VX printer, the SD card method was chosen, see Figure 10. This process is no different for any type of model. The first model was a printed respirator using a ZMorph printer. We started by printing the second part of the model and thus the plastic filter. Two pieces of plastic filter software calculated for 1 h and 56 min of printing. This piece lasted 60 min. The ZMorph printer is not characterized by fast printing, but the quality of the prints is at a high level. The whole printing of the two pieces took the expected 1 h and 56 min. The \"propeller\" is sufficiently reworked. No major deficiencies or excess material are detectable. As a second model, the body of the respirator was made. It is not much more difficult to print and was printed only in one piece. Significantly more material was used, as the model does not contain as many holes as a plastic filter. It contains only one large hole in the middle and four smaller holes on the sides. In Figure 11 is the body of the respirator pressed from a red ABS string. The rolls of strings are placed above the printing surface to ensure the supply of material in an uncomplicated form. It took about 85 min to press the body of the respirator. The extruded heat also has no major drawbacks. The dimensions remained  
Figure 9: Respiratory body, two pieces of plastic filter and plastic filter cover in Voxelizer software. inact. Only the sequence of application of the last layers can be seen. However, this does not affect the quality and function of the printout. Subtle imperfections can be observed in the individual parts. A closer look at the respirator shows the stratification of the string with the naked eye. With the touch of a finger, it is possible to feel traces of the string or the transitions from layer to layer. When making holes to hold the respirator around the face, the ZMorph printer hesitated slightly, However, it does not affect the functionality of these holes.