Additive manufacturing (AM) of metal powder by electron beam fusion offers significant advantages compared with traditionalsubtractive manufacturing techniques as well as certain advantages of production rate and post processing, over laser SLMsystems. EBM AM technologies have continued to develop over recent years in particular for medical implants and aerospaceparts, and new vendors of such AM machines are developing more advanced systems with additional in process metrology. In spiteof the clear advantages, E beam AM suffers from limitations which need to be addressed before wider take up of the technology isachieved.
During the powder delivery process, which occurs many thousands of times during a part build, there is potential for defects in thepowder delivery process. Such defects take the form of score trenches running perpendicular to the powder delivery direction,vibration ripples parallel to the delivery direction, excessive powder delivery due to damage to the powder rake and lack of powderdue to under dosing problems. Like-wise during the layer build process it is important to monitor out of plane defects on parts suchas thermal swelling. In-plane information regarding the boundary of the melted powder and unmelted powder are equally importantto monitor in plane geometry.
This paper describes the development and deployment of a newly patented, in-process metrology system on a recently launchedcommercial EBM AM machine. The inspection system, which is fully integrated into the AM machine control system, is based onsingle camera, phase measurement profilometry. A temporal synchronisation technique is employed for data capture and usingautomatic machine triggering an acquisition time of 2 seconds per measurement is achieved. A novel calibration method based on asurface fitting algorithm is deployed to reduce the influence of phase error and random noise. The paper gives examples of the systembeing deployed on the build of typical parts and shows examples of powder delivery assessment and post build layer measurementand describes the integration of the metrology system with the AM machine control systems.
|Title of host publication||Proceedings of the 20th International Conference of the European Society for Precision Engineering and Nanotechnology, (EUSPEN)|
|Subtitle of host publication||Virtual Conference 2020|
|Editors||R. K. Leach, D. Billington, C. Nisbet, D. Phillips|
|Number of pages||4|
|Publication status||Published - 8 Jun 2020|
|Event||20th International Conference of the European Society for Precision Engineering and Nanotechnology - Virtual Conference , Geneva, Virtual, Austria|
Duration: 8 Jun 2020 → 12 Jun 2020
Conference number: 20
|Conference||20th International Conference of the European Society for Precision Engineering and Nanotechnology|
|Period||8/06/20 → 12/06/20|