CORRELATION BETWEEN PYROMETER MONITORING AND ACTIVE ILLUMINATON IMAGING OF LASER ASSISTED ADDITIVE MANUFACTURING OF STAINLESS STEEL

摘要

Laser assisted additive manufacturing which can e.g. bernused for manufacturing of 3-D parts from stainless steelrnpowder layer-by-layer by assist of laser beam. Stainlessrnsteel is molten selectively with laser beam and solidifiedrnlayers of material, attached to each other, form desired 3-rnD structure.rnNowadays range of materials that can be used for laserrnassisted additive manufacturing is widened and highrnautomation level of equipments has made this methodrnmore interesting process for manufacturing. This is whyrnalso methods to control the process have started to gainrnan essential role in laser assisted additive manufacturingrnprocesses. Control of process parameters is also essentialrnto get good appearance, good quality and good strengthrnproperties of work piece still maintaining the optimumrnprocessing speed. Control of temperature in of process isrnmost important of all numerous process factors.rnThe objective of this study was to monitor selective laserrnmelting process simultaneously with pyrometer andrnvideo camera system with active illumination. Aim ofrnthis study was also to find out correlation betweenrnphenomena captured with imaging system and pyrometerrnmeasurement data.rnAll tests in this study were carried out at LappeenrantarnUniversity of Technology with trial set-up of IPG 200 WrnSM CW fiber laser and a layer of metal powder. An inertrnatmosphere was simulated by nitrogen gas flow duringrnprocess. Material used in this study was EOSrnStainlessSteel PH1.rnResults indicate that several phenomena observed fromrnvideo imaging system had correlation to pyrometerrnmeasurements. This makes pyrometer monitoringrnsuitable method for controlling laser sintering process.