Monitoring of Single-Track Degradation in the Process of Selective Laser Melting

Selective laser melting machines provide the optimal working parameters for manufacturing during the process. However, the laser interaction with metal powder is an unstable. The gasdynamic flows make powder particles move and escape from the melt pool. This phenomenon leads to an irregular distribution of the material volume being remelted. Since the energy is constant during the process, single-tracks with different geometry are appeared and their superposition forms the 3D-object. To detect the process abnormality of stable track formation there was developed a control system based on morphological analysis of thermal image obtained by IR-camera. The temperature field distribution along the image matrix’s row with the maximum temperature was used as influencing factor on stable track formation. Roughness was reduced from 39.9 to 6.6 µm by using control system with the same process parameters. The obtained results can be applied in industrial SLM machines with the integrated active control system.Mechanical Engineerin

Study of oxygen effect on the melting pool temperature during selective laser melting

The on-line optical diagnostics studies of selective laser melting are difficult to accomplish due to the need of closed chamber of inert gas protective atmosphere. In this term, this study was initiated to make evidence of oxygen influence on the signal from the melt pool. The results make clear the temperature growth with presence of oxygen and its effect on the metallurgical contact of the single-track to the substrate. It was shown that for both used materials, the oxidation leads to an overheating but the metallographic quality differs. The experiments highlighted that the optical diagnostic means such as IR thermography camera is suitable but not sufficient solution for process control and it needs adequate evaluation. Using the track width as an approximation of the melt pool width at melting point, it was possible with some assumptions to restore the true temperature of the studied zone

Study of layers’ structure defects of 3D objects obtained by selective laser melting

Current work was aimed to study of layers’ structure defects of 3D-objects obtained by selective laser melting with the modulated laser beam mode. Traditionally Gaussian laser beam mode uses for the processing in selective laser melting. On the developed experimental setup, the alternative laser beam modes as Flat-top and Inverse Gaussian were obtained. With the carried out experiments 3D-objects contained 10 layers were produced from CoCrMo powder with the diameter of granules less than 20 μm. The layers’ structure defects as penetration of the substrate material into the body of produced objects were studied by optical and scanning electronic microscopy

Modeling of 3D technological fields and research of principal perspectives and limits in productivity improvement of selective laser melting

Nowadays the technological perspectives of selective laser melting are limited by available equipment on the market. Most of the manufactures produce SLM-machine with the maximum power of laser system 200 W, this makes processing very slow and it significantly reduces the field of potential applications for the technology. Meanwhile the limits of laser power are linked to a problem of its effective use. In the current work, the future perspectives of technology are investigated by modeling of 3D technological fields