Acoustic monitoring method for additive manufacturing processes
A method of monitoring an additive manufacturing process in which a directed energy source is used to create a weld pool at an exposed build surface of a mass of powdered material, and selectively fuse the powdered material to form a workpiece, the method including measuring acoustic energy generated by the weld pool to generate a measured acoustic profile.
1. A method of monitoring an additive manufacturing process in which a directed energy source is used to create a weld pool at an exposed build surface of a mass of powdered material, and selectively fuse the powdered material to form a workpiece, the method comprising:
measuring acoustic energy generated by the weld pool to generate a measured acoustic profile; and
controlling at least one aspect of the additive manufacturing process in response to the measured acoustic profile,
wherein the step of controlling includes taking a discrete action in response to the acoustic signal profile deviating from a baseline acoustic profile.
2. The method of claim 1 further comprising comparing the measured acoustic profile to the baseline acoustic profile.
3. The method of claim 2 wherein the baseline acoustic profile is representative of a known good workpiece.
4. The method of claim 2 wherein a difference between the measured acoustic profile and the baseline acoustic profile indicates the presence of a defect in the workpiece.
5. The method of claim 1 further comprising monitoring a position of the weld pool while measuring the acoustic signal.
6. The method of claim 5 wherein the position of weld pool is monitored by two or more spaced-apart acoustic sensors positioned at known locations relative to the mass of powdered material.
7. The method of claim 1 further comprising storing a record of the measured acoustic profile.
8. The method of claim 1 wherein the discrete action is stopping the additive manufacturing process.
9. A method of making a workpiece, comprising:
depositing a powdered material so as to define a build surface;
directing a build beam from a directed energy source to create a weld pool in the build surface, and selectively fuse the powdered material in a pattern corresponding to a cross-sectional layer of the workpiece;
measuring acoustic energy generated by the weld pool to generate a measured acoustic profile; and
controlling at least one aspect of the method of making the workpiece in response to the measured acoustic profile,
wherein the step of controlling includes taking a discrete action in response to the acoustic signal profile deviating from a baseline acoustic profile.
10. The method of claim 9 further comprising comparing the measured acoustic profile to the baseline acoustic profile.
11. The method of claim 10 wherein the baseline acoustic profile is representative of a known good workpiece.
12. The method of claim 10 wherein a difference between the measured acoustic profile and the baseline acoustic profile indicates the presence of a defect in the workpiece.
13. The method of claim 12 further comprising repairing the defect by using the directed energy source to create a weld pool over the defect, permitting previously-fused material to flow into and fill the defect.
14. The method of claim 9 further comprising monitoring a position of the weld pool while measuring the acoustic signal.
15. The method of claim 14 wherein the position of the weld pool is monitored by two or more spaced-apart acoustic sensors positioned at known locations relative to the mass of powdered material.
16. The method of claim 9 further comprising storing a record of the measured acoustic profile.
17. The method of claim 9 wherein the discrete action is stopping the additive manufacturing process.