Laser Metal Deposition (LMD) has been developed forrepair of damaged components and for the directforming of three-dimensional structures. From theaspect of productivity, shape accuracy of the depositmust be improved to shorten the machining processafter LMD. The objective of this work is to controlbuild-up shape by adjusting weld pool size.Configurations of deposits made with various LMDprocess conditions were measured by cross sectionalobservation. In addition, signal intensity of heatradiation, plume emission and laser reflection fromweld pool were monitored by photodiodes integrated ina laser processing head during the LMD process. Theresults showed strong correlation between weld poolsize and signal intensity of heat radiation. An adaptiveshape control system, which consists of an in-processmonitoring system and Proportional-Integral-Derivative (PID) controller using that correlation, wasdeveloped for controlling build-up shape. Due to thelinear relationship with weld pool size, laser powerwas selected as a PID output parameter adjusted byheat radiation signal. Since the target value of heatradiation signal can be changed flexibly during LMDprocess in our PID control system, deposit shape issuccessfully controlled as required with sufficientprofile accuracy of build-up layers.
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