Melt pool temperature modeling and control for Laser Metal Deposition processes

Melt pool temperature is of great importance to deposition quality in laser metal deposition processes. To control the melt pool temperature, an empirical process model describing the relation between the temperature and laser power, powder flow rate, and traverse speed is established and verified experimentally. A general tracking controller using the Internal Model Principle is then designed. To examine the controller performance, two experiments tracking a constant temperature reference and a time varying reference are conducted. The results are compared to open-loop experiments where the laser power profile is derived directly from the model. The results show the melt pool temperature controller performs well in tracking both constant and time varying references and that the closed-loop control system greatly reduces the tracking errors.