Thermographic in-situ process monitoring of the electron-beam melting technology used in additive manufacturing

Metallic materials for 3D printing

“…Additional steps can include in situ monitoring of each and every layer using optical and thermal imaging. 112 These in situ thermal and optical data are then spliced together with process parameter log fi les and provided as boundary conditions to computational process and materials modeling. 35 These models will be able to predict any tendency for defect formation as well as microstructural heterogeneity.…”

Sensors on 3D Printers for Cloud Printing Service

“…Similar work is described by Craeghs et al [10] on Selective Laser Melting (SLM) for the purpose of process monitoring. For EBM manufacturing, Dinwiddie et al [11] propose an optical system for layer-wise process monitoring with the aim of process control. Most of the recent research is in the state of working prototypes without actively controlled processes and specific for a class of AM machinery.…”

A review on measurement science needs for real-time control of additive manufacturing metal powder bed fusion processes

“…It was reported that a minimum defect size around 400 μm is detectable with this system. Dinwiddie et al developed a high speed IR thermographic imaging system with an integration time of 1.0 ms, retrofitted to a commercial electron beam machine, to monitor beam-powder interaction, quantify beam focus size, and detect porosity [60]. To overcome the contamination of the optics due to free metal ions released during the process, they designed a shutterless viewing system allowing continuous IR imaging of the beam-powder interaction.…”

“…This requires that only radiation sensor systems with narrow bandwidth near that designed for the f-theta lens may be used accurately [8], [45], [57]. Finally, metallic debris from the HAZ can coat a window or viewport used in an AM imaging system, and disturb temperature measurements by changing the radiation transmission through the window [49], [51], [58]. This is particularly troublesome in electron-beam melting (EBM) systems, and prompted Dinwiddie et al to create a system to continuously roll new kapton film over the viewport in order to provide new, unsullied transmission [49].…”

“…In these systems, the field of view follows the melt-pool throughout its scan trajectory. Alternatively, the imager may be set externally to the build chamber to view the build through a window [49]- [53]. An improvised method was developed by Craeghs et al [8].…”