## 1 Introduction  
The laser sintering (LS) of polymer powders is a primary shaping process by definition. A solid body is created out of an unstructured and formless powder bed by the energy input (laser radiation). This means that besides the shape, the properties of the part will also be created during the build process to a great extent. The characteristic of the used powder has an especially large influence on the part properties, as was recently summarized by [PERSON] et al. [1]. Furthermore, almost all of the material and production parameters influence the final properties of the LS parts. The interference of different build-parameters, but also their difficult and precise control, has far-reaching consequences for the fabricated parts. For LS parts, an exact prediction of the properties is thus difficult [2]. Moreover, the highly complex LS parts are influenced by their three-dimensional orientation in the building chamber of the LS-equipment. In the scientific literature, numerous investigations are described regarding correlations of single build parameters and their combinations on part properties. The following list assembles some important works in this area:  
* Influence of the energy density (Andrew number (\(A_{\mathrm{n}}\))) [3,4];
* Influence of molecular properties of the polymer on the micro-structure of the parts [5];* Energy density (\(A_{\rm n}\)) and part orientation in a build envelope [6];
* Incomplete coalescence of polymer melt and resulting process problems [7];
* Influence of powder refreshment and build temperature at a constant energy density (\(A_{\rm n}\)) [8];
* Influence of Energy density (\(A_{\rm n}\)) in combination with powder layer thickness [9];
* Influence of Energy density (\(A_{\rm n}\)) in combination with powder shape [10];
* Variations of temperature in a build envelope and part cylinder [11].  
It can be recognized from this shortened list with selected non-linear correlations how critical the control of the LS-process can be regarding predictable LS-part properties. In a larger screening work by [PERSON] et al. [12], the laser power, laser speed, scan spacing, powder bed temperature, layer thickness, and orientation of the parts in the build chamber were investigated, and it could be revealed that scan spacing, in combination with layer thickness, are the most significant in terms of the part density and mechanical properties, if the other parameters are constant.  
What is noticeable is that in almost all of the studies mentioned above, the examination is dedicated to only one LS-material. A comparison of the processing behavior and the part properties on at least two materials, as in this study, is rarely done [10; 13]. This is surprising, as from a commercial point of view, LS materials have been available for a long time from different sources. Both the company Evonik (Marl, Germany) and the company Arkema (Colombes, France) supply the polyamide 12 (PA12) polymer powders processed in LS. Evonik powders are distributed through the machine suppliers EOS (Krailling, Germany) and 3D-Systems (Rock Hill, SC, USA) under the trade names PA 2200 (EOS) and Duraform(r) PA (3D-Systems), and are therefore widely dispersed and dominate the LS market. Arkema directly supplies the LS-powder under the trade name Orgasol(r) Invent Smooth to the market, independently of the major machine manufacturers.  
Due to the fact that all three materials are identical regarding their primary chemical structure, as they are all polyamide 12, the comparison of these materials and the resulting parts can be concentrated on secondary factors, like powder shape, particle size distribution, thermal behavior, and microstructural and morphological differences. It is well known in the community of LS-users (service bureaus) that the powders from the different sources behave differently in the LS-process and create different part characteristics. A refined investigation on the influence of powder origin on the laser sintering process and laser-sintered parts is hence obvious.