Monitoring offers AM traceability

Written by: Paul Fanning | Published:

The use of in-process monitoring (IPM) in a new additive manufacturing system promises greatly improved traceability.

One of the challenges that has continued to frustrate users of metal additive manufacturing (AM) systems for production applications (in terms of quality AND traceability) is capable and useful in-process monitoring (IPM).

From the outset, this issue has been a key focus for Wayland Additive during the development of its innovative and ground-breaking Calibur3 platform featuring its proprietary NeuBeam technology. That is to say that as the Wayland team started to build its new system from the ground up, in-process monitoring was included as a key function — it is not an add-on or an afterthought.

NeuBeam technology has been developed in-house from the ground up by a team of physicists that have worked for many decades with electron beam technology and industrial systems in the semi-conductor industry. NeuBeam is a truly ground-breaking metal AM process that effectively neutralises the electron beam (eBeam) powder bed fusion (PBF) process to offer greater flexibility than laser-based AM processes while overcoming the stability issues many users of traditional eBeam AM systems experience. In addition, the NeuBeam® process enables metallurgical requirements to be tailored to application requirements rather than the previous limitations of the process — to produce optimum results.

NeuBeam also offers significant advantages over other technologies with built-in real-time in-process monitoring (IPM), allowing for rapid material development or tuning of microstructures by adapting the solidification during manufacture. With NeuBeam the process temperature is not constrained by sintering the powder bed, allowing the process temperature to be optimised to the material microstructure and/or the application.

The original plans to launch and showcase the full capabilities of the Calibur3 machine in January have had to be delayed due to the Covid-19 lockdown restrictions. As such, the global virtual launch for Calibur3 is now scheduled for March 16th 2021. The physical launch, which will see Wayland welcoming visitors to the now complete Development Suite for production partnerships in Huddersfield, has been postponed until May 19th sensitive to the latest travel regulations and guidelines.

Ahead of these new dates, Wayland Additive is keen to share some of the innovative capabilities that really sets the Calibur3 apart within the AM industry.

The Wayland approach to IPM incorporates three independent but complementary IPM processes, which in and of itself, demonstrates that there is currently no single process that can provide all of the in-process data that full traceability requires. This three-fold approach is unprecedented and the collective benefits of infrared cameras, structured light scanning, and electron imaging provide extensive and detailed data on every part that comes off a Calbur3 system.

Every Calibur3 incorporates an advanced and well-established high speed CMOS camera working in the NIR range and operating at four Megapixels at 100 FPS, up to a maximum of 25,000 FPS at small resolution. The IR camera is calibrated to measure temperatures in the range of 600 to 1500°C in order to provide absolute temperature measurements and cooling rates as well as being able to identify phase changes. In this way the IR Camera can provide real time temperature mapping — temperatures calculated in real time via GPU processing. Moreover, measured temperatures can be presented in 3D for improved visualisation and the resulting plot can be interactively panned, zoomed and rotated — also in real-time.

This type of thermal mapping can be used to monitor part dimensional accuracy, powder spreading during the build, energy absorption and any out-of-plane defects, that are not visible to the naked eye. This capability is particularly advantageous for rapid material development.

The structured light scanning system featured in the Calibur3 is based on the synchronization of a second CMOS camera and a light projector system. This system permits multiple fringe patterns to be projected onto the build area and captured by the camera. As a result, the system can calculate the z-axis (height) of every point on the build and thus produce an accurate height surface map of the powder bed. Any out of plane defects, on any layer in the build, caused by powder spreading or part swelling for instance, can then be easily detected and quantified.

This system allows post-build defect and quality analysis to assist with process development, but Wayland’s technology roadmap will see this integrated into closed loop machine control algorithms over the next couple of years.

The backscattered electron detector — or electron imaging — process is able to detect the primary electrons (i.e those emitted directly from the electron gun) that have been scattered back from the nuclei of atoms in the target material. Different element compositions and phases will interact differently with the electrons and thus appear distinct within the build chamber. The BED process can also detect localized ionization in the vicinity of the meltpool. This capability is unique to Wayland Additive’s NeuBeam process and the active charge neutralisation system.

This monitoring process provides useful data about the element composition and the grain structure within the parts that can be analysed and used to support traceability and demonstrate internal quality of the parts.

In short, Wayland Additive has prioritised the production requirements of quality and traceability for complex metal parts, which has been achieved with a dedicated and intelligent approach to IPM. Not only does this comprehensive monitoring approach greatly improve the quality of the parts off the machine, but it also specifically supports and improves operator experience. For the first time, operators can monitor the full process including the cooling cycle, which can be altered to change the microstructure of parts to suit their needs.

NeuBeam is the most transparent metal additive manufacturing process to date, offering full traceability and eliminating the black box approach to AM that has dominated the industry for so long.


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