## 4 Conclusions  
Additive manufacturing of CCFRP parts with the LS machine developed aims to combine the process-specific advantages of the LS process with the advantages of continuous fibre reinforcement. With this LS machine, in the future, complex shapes and near-net-shape functional parts with promising basic properties (matrix) will be able to be reinforced in a load-path-oriented manner with the help of continuous fibres. Thus, CCFRP parts can be produced economically without support structures and cost, as well as time-consuming post-processing steps. The starting point of this study was an initial starting point from previous research work, which enables roving integration but is particularly unfavourable with regard to the processing time and the achievable FVC. High process times are required to integrate rovings, which results in inefficient production. In addition, the HAZ at the initial starting point is too large, which means that rovings can only be placed at a considerable distance from the part edges. The FVC and the associated mechanical properties of the CCFRP parts can thus only be increased slightly. To systematically increase the FVC and the mechanical properties in future research work, a comprehensive understanding of the process was derived in this paper. Based on this, the LS process with continuous fibre integration was optimised in terms of process time, process reliability and the shape of the HAZ. The essential core conclusions of this study are summarised in the following points:  
* In the first study of this paper, both the law of heat conduction, as well as the law of heat radiation, as in Equations (2) and (3), can explain the findings on the effects of the influencing variables on the target variables in a first approximation;
* To obtain the narrowest but deepest possible HAZ, a small nozzle diameter and a small nozzle distance should be selected. The nozzle curvature should be convex for a large diameter. For a small diameter, a planar nozzle can be used instead. Nozzle temperature has a balanced effect on the width-to-depth ratio of the HAZ. A low feed rate is beneficial to the shape of the HAZ. However, since a high process speed is also required, there is a trade-off;
* In the second study, the target variables were analysed in more detail with the help of a CCD. The coefficient of determinations for the width with R\({}^{2}\) = 0.8051 and the \begin{table}
\begin{tabular}{c c} \hline \hline  & **Operating Points** \\ \hline \(\kappa\) & Planar \\ \(\mathrm{d_{D,o}}\) (mm) & 2 \\ \(\mathrm{h_{D}}\) (mm) & 0.6 \\ \(\mathrm{T_{D}}\) (\({}^{\circ}\)C) & 340 \\ \(\mathrm{v_{D}}\) (mm/min) & 140 \\ \(\mathrm{T_{HMG}}\) (\({}^{\circ}\)C) & 190 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Identified operating points evaluated as optimal for reproducible and process-reliable roving integration. depth with R\({}^{2}\) = 0.7178 were close to 1. The developed regression models, therefore, describe the target variables quite well. Possible reasons for the lower coefficients of determination are thermal expansion of the fibre integration unit, deviations in temperature setting via the PLC, play between the roving and the inner diameter of the fibre nozzle, as well as scattering effects, due to the laser-sintering process (material, the position of specimens in the powder bed, etc. );
* With the help of this study, an increase in the nozzle feed rate of 233% up to 140 mm/min was demonstrated for the integration of rovings. Thus, more economical production of CCFRP parts in the developed LS machine is now possible. The width and depth of the HAZ were reduced to b\({}_{\text{HAZ}}\) = 2638.72 \(\upmu\)m (\(-\)56%) and t\({}_{\text{HAZ}}\) = 523.36 \(\upmu\)m (\(-\)44%), respectively, so that rovings can now be integrated closer to the part edges and, thus, the FVC can be set higher. This study, therefore, provides optimised operating points for future research;
* Limitations, nevertheless, arise in the processing time.