Acoustic signals associated with laser-substrate interaction in powder bed fusion additive manufacturing process

During the Powder Bed Fusion Additive Manufacturing Process, flaws are sometimes produced in the component. It is desirable to detect these flaws during the deposition process, so that they might be remediated before they become captured within the part. A pilot study was conducted to see if acoustic data might show some signature or variation when such flaws are produced. This paper will provide some observations on acoustic data recorded during such an additive manufacturing deposition process. Acoustic data were collected within the chamber during the Powder Bed Fusion Additive Manufacturing Process in a 3D Systems Launches Pro-X 320 Direct Metal Printer. A PCB ¼ inch model 378A14 pre-polarized piezo-electric pressure microphone with an integrated preamplifier was the sensor used to detect acoustic signals. Tonal noise associated with pumps obscured the spectral region below 10 kHz, but significant acoustic output associated with the laser-substrate interaction was present from this lower limit. A small cylinder was produced for test, during which intentional process variations were introduced. A CT scan of the cylinder was used to locate flaws, and to register these locations, and thus to attempt to correlate these flaw locations with time windows in the acoustic data.