# Conformal 3D Material Extrusion Additive Manufacturing for Large Moulds
## 2 Materials and Method
### Large-Scale Hybrid Manufacturing Machine  
The proposed methodology can be reproduced in large-scale hybrid manufacturing machines, as demonstrated in the following paragraph. Indeed, the composite lamination  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Unit** & **PLA** & **PVA** \\ \hline Layer Height & mm & 0.2 & 0.3 \\ Initial Layer Height & mm & 0.22 & 0.35 \\ Line Width & mm & 0.5 & 0.5 \\ Wall Line Count & - & 2 & 2 \\ Infill Density & \% & 100 & 100 \\ Printing Temperature & \({}^{\circ}\)C & 202 & 160 \\ Build Plate Temperature & \({}^{\circ}\)C & - & - \\ Flow & \% & 100 & 100 \\ Print Speed & mm/s & 50 & 50 \\ Initial Layer Print Speed & mm/s & 25 & 25 \\ Travel Speed & mm/s & 80 & 80 \\ Retraction Distance & mm & 2 & 2 \\ Fan Speed & \% & 100 & 100 \\ Regular Fan Speed at Height & mm & 0.2 & 0.3 \\ Support Structure & - & None & None \\ \hline \hline \end{tabular}
\end{table}
Table 1: Slicing printing settings used for both PLA and PVA filaments.  
on moulds manufactured following a conformal approach gives advantages in terms of stiffness and strength of the mould itself. This is particularly true in the case of moulds with remarkable dimensions, typical of marine, aerospace, or automotive applications.  
Consequently, the software developed for the material deposition AM machine has been tested on a large-scale AM-CNC machine capable of producing moulds up to 5 m. This final test has been carried out to verify the possibility of using the proposed approach on industrial machines. Indeed, the approach was applied to a large-scale CNC own-built gantry machine with a 5 \(\times\) 3 \(\times\) 2 m working area to prove the practical implication of the discussed methodology. A T-Max 657 extrusion machine from Graco company [34] has been selected for this specific research. A large-size nozzle extrudes the Raku-Tool Cp 6070 modelling clay, and the outlet diameter is tuned depending on the material used in the moulds' manufacturing [35]. To provide the reader with some data, the range of nozzle dimensions used to manufacture the large-scale sample test goes from 0.8 to 1.2 mm in diameter for the tested materials. The machine is built around an IndraMotion MTX Micro actuation system and is managed through the Bosch Rexroth human-machine interface without any change in the hardware. The axes are moved by three brushless motors Indra Dyn S QSK061; a customised PLC board manages the extruder.  
The requirements for milling in terms of axis speed and stiffness are more significant than those required in additive manufacturing mode. From the software point of view, a re-compilation of the Bosch Rexroth control environment was necessary to read the new hybrid G-code developed for the sake of this research: the human-machine interface was not modified, but only the lines of the code in which the CNC machine control software acquires the G-code.  
An overall recap of the tests performed on the desktop and the large-scale machines is shown in Figure 7, along with the materials used for each layer of the final mould.  
As the results will demonstrate, the methodology herein developed is feasible and can be extended to sizeable 3D printing machines where the impact of the cost of the moulds on the final products can be high, similar to what is described in [36]. Compared to traditional mould manufacturing, the proposed approach uses AM and CNC tools to produce moulds with a more efficient workflow; indeed, the integration of a conformal 3D spatial deposition boosts the efficient coating deposition over the moulds.  
Figure 7: Schematic representation of the tests used to validate the proposed methodology for desktop and large-scale hybrid manufacturing machines.