## 1 Introduction
The core element of this prototypical LS machine is a fibre integration unit for integrating the rovings into the already manufactured layers of the part. A heated fibre nozzle is used to liquefy the polymer locally, creating a heat affected zone (HAZ) with a characteristic width and depth. The roving is then placed into the liquefied melt by a synchronised sequence of motions between the roving feed rate and the nozzle feed rate. In [20], the extended LS process was analysed regarding temperature management during fibre integration to identify operating points for curl-free integration of rovings. In [19], the influence of the process and material parameters on the shape of the HAZ was investigated using a simplified experimental setup. The results in [19; 20] provide the first starting points for successful fibre integration and form the basis of this paper. However, the identified starting points lead to the inefficient production of CCFRP parts. The production speed is relatively slow, so the rovings can only be embedded into the part at a low feed rate. The low feed rate leads to an uneconomical and time-consuming production of CCFRP parts. In addition, the HAZ's width and depth are too large, so the rovings have to be placed far away from the part edges. The consequence of a too large HAZ is that the FVC and the associated mechanical properties can only be set low. Thus, the potential of this new LS process with continuous fibre integration remains undiscovered. A comprehensive understanding of the rovings' integration process in the developed LS machine is indispensable to achieve an economical production of LS parts with a high FVC and, thus, high mechanical properties. Only with knowledge of the main influencing variables and their interactions on the roving integration process is it possible to optimise the width and depth of the HAZ and the processing time in a targeted manner. Therefore, this paper aimed to experimentally characterise and optimise this novel laser-sintering process with automated continuous fibre integration. Based on the identified and initial operating points in [19; 20; 21], the main influencing variables and interactions on the formation process of the HAZ were systematically investigated using a split-plot design (SPD). In a subsequent study, the target variables were analysed more thoroughly using a central composite design (CCD). Section 2.1 first presents the principle of automated continuous fibre integration. The influencing variables on the fibre integration caused by the fibre integration unit, and the target variables to be optimised are discussed in the same section. The SPD is presented in Section 2.2. For a detailed analysis of the target variables at a predicted operating point, the procedure for the CCD is described in Section 2.3. Section 3 presents the results and their interpretation. Section 4 discusses the results in relation to the initial state. In this study, an increase in the process time of 233% was demonstrated for the integration of the rovings. Thus, a more economical production of CCFRP parts in the developed LS machines is now possible. The width and depth of the HAZ were reduced by 56% and 44%, respectively, so the rovings can now be integrated closer to the part edges, and thus the fibre volume content (FVC) can be set higher. This study, therefore, provides optimised operating points for future research to increase the FVC and the associated mechanical properties systematically.