Melt pool temperature control using LabVIEW in Nd:YAG laser blown powder cladding process

In laser cladding, the substrate temperature increases as the process progresses, which can lead to excessive dilution, the formation of a heat-affected zone (HAZ), thermal distortion and cracking due to the build-up of residual stresses. The feasibility of controlling heat build-up and dilution through on-line temperature control during Nd:YAG laser cladding is investigated using a LabVIEW graphical program with a real-time proportional, integral and derivative (PID) controller to control the temperature of the melt pool. Cladding trials were performed with and without temperature control. The effects of laser cladding conditions such as the substrate scan rate and powder feed rate on clad dilution and HAZ were determined by quantitative metallography. Results indicate that while the LabVIEW system can control the melt pool temperature, this does not necessarily result in a quality clad layer and highlights the need for multi-parameter process control.