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Case Study

Laser ultrasonic for AM in-process inspection

Project challenges

Current Additive Manufacturing (AM) in-process inspection relies mainly on surface measurements, potentially missing subsurface defects. These subsurface defects can have a large impact on the usability of components and early detection enables the possibility of remedial action to be taken or early scrappage before additional value added post-processing takes place.

Business challenge

  • Process Innovation

Sector

  • Aerospace

Technology or capability

  • Metrology & NDT

  • Additive Manufacturing

Project Challenges

Fast and accurate online evaluation of defects in additively manufactured parts.

The MTC has developed a noncontact inspection capability in Laser Ultrasonic Testing (LUT) for non-contact detection of voids in Additively Manufactured parts.

Current Additive Manufacturing (AM) in-process inspection relies mainly on surface measurements, potentially missing subsurface defects. These subsurface defects can have a large impact on the usability of components and early detection enables the possibility of remedial action to be taken or early scrappage before additional value added post-processing takes place.

Laser powder bed fusion (L-PBF) and Directed Energy Deposition (DED) AM processes work at elevated temperatures. This prohibits the use of many conventional contact inspection techniques.

MTC's Solution

Laser Ultrasound Testing (LUT), a non-contact method, is capable of working at elevated temperatures. The system at the MTC is capable of inspection on rough samples such as those generated by AM processes.

Inspection proven on Ti64 cuboid calibration samples with Electric Discharge Machining (EDM) through holes representing subsurface defects.

A more complex geometry, realistic aluminium part was inspected from the AMAZE project (design from Thales Alenia Space), which had been validated using X-ray Computed Tomography.

Due to its unique layer-by-layer or bead-by-bead build method, Additive Manufacturing (AM) is ideal to apply in-process inspection, with the potential advantage to reduce or eliminate the need to inspect after the full build or after machining. Furthermore, for very complex and large components post build inspection methods will struggle and in-process inspection may be the only approach.

Ben Dutton, Technical Specialist - Non-Destructive Testing

The Outcome

LUT was proven to be an effective tool for the identification of subsurface voids in both calibration parts and realistic geometries.

The remote, non-contact method offers a solution for in-process inspection of additive processes.

Benefits to the Client

LUT offers a solution for in-process monitoring of novel manufacturing processes, bringing the inspection earlier in the process so that defects can be identified and remedial action taken before additional post-processing value has been added to the component.

LUT shows good potential to be modified for automated inspection.

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