Additive Manufacturing (AM) is an uprising manufacturing process for parts with complex geometries and low production quantities. Within the layer-wise building process, less additional processes are needed, to produce the parts. This allows a building of parts within a reasonable time- and costs-range. Especially industries, such as aerospace industry, can profit from AM. Electron beam – Powder bed fusion (EB-PBF) is a common technique, within AM, to produce metallic parts out of special alloys such as Alloy 718. This superalloy is a Nickle-Iron based alloy that has high mechanical properties, even in elevated temperatures (up to 650ºC). The combination of such material properties with high geometrical freedom creates new opportunities for the industry. However, it must be noted that a significant drawback of AM-techniques is the need for post-processing because of surface roughness- and microstructural characteristics. Commonly, the produced parts utilize mechanical post process such as milling to provide good surface roughness and dimensional accuracy. To reduce the surface roughness in the contour region, and therefore reduce the amount of mechanical post-processing, the present survey elaborates the effect of relevant parameters on contours such as the number of contours, scanning speed, focus offset and beam current. By using Design of Experiments (DOE), two batches were carried out: one screening batch and a two-level-full factorial design. In those batches, 15×15×15 mm cubes were printed with various parameters and, after that, analysed by using White light interferometry (WLI), Optical microscopy (OM) and Scanning electron microscopy (SEM). Furthermore, the program ImageJ was used to perform porosity and melt pool measurements. It had been observed that the number of contours had quite a considerable impact on the final surface roughness and the number of defects. Samples with two contours, instead of only one, tend to have a lower surface roughness. Nevertheless, the parameters and their interaction were found to have fundamental effects on the resulting surface roughness and microstructure.

This thesis presents an experimental research study aimed at identifying the optimal mechano-chemical surface treatment for powder metallurgy gears utilized in electric vehicles (EVs). The primary objective of the study is to determine the most effective surface treatment method in terms of enhancing gear transmission efficiency. The experiments utilise a specialized FZG test rig, which allows for comprehensive testing under realistic operating conditions. In addition, a surface roughness measurement device is used to evaluate the impact of the surface treatments on the gear's surface characteristics. The results obtained from the experiments reveal a particular type of surface treatment as the most effective among the test samples considered within the scope of the thesis, as it significantly improves gear transmission efficiency. These findings contribute to the advancement of surface treatment techniques for powder metallurgy gears used in EVs, aiding in the development of more efficient and high-performing gear systems for electric mobility. / Denna avhandling presenterar en experimentell forskningsstudie som syftar till att identifiera den optimala mekano-kemiska ytbehandlingen för pulvermetallurgiväxlar som används i elfordon (EV). Det primära syftet med studien är att fastställa den mest effektiva ytbehandlingsmetoden när det gäller att förbättra effektiviteten i växelöverföringen. Experimenten utförs med hjälp av en specialiserad FZG-testrigg, som möjliggör omfattande tester under realistiska driftsförhållanden. Dessutom används en ytråhetsmätningsanordning för att utvärdera effekten av ytbehandlingarna på kugghjulets ytegenskaper. Resultaten från experimenten avslöjar en viss typ av ytbehandling som den mest effektiva bland de testprover som betraktas inom ramen för avhandlingen, eftersom den avsevärt förbättrar växeltransmissionens effektivitet. Dessa fynd bidrar till utvecklingen av ytbehandlingstekniker för pulvermetallurgiska redskap som används i elbilar, vilket hjälper till att utveckla mer effektiva och högpresterande växelsystem för elektrisk mobilitet.