Instantaneous powder flux regulation system for Laser Metal Deposition

A new control system for regulating the powder flux during the laser metal deposition process (LMD) has been designed, developed and validated. The powder regulation system is based on a solenoid, which is coupled to the LMD nozzle and controlled by means of a Pulse Width Modulation (PWM) signal. Thanks to this system, the deposited clad height can be regulated depending on the process parameters, what allows obtaining a more homogeneous layer height and results in a more stable process. The material over-height at the beginning of the clad has been completely avoided when the control is applied. The material accumulation in corners where the deposition direction is changed has been also reduced from 0.65 mm to 0.35 mm. Furthermore, simulations of the nozzle and the powder particle stream have been carried out in order to validate the designed system and analyze the powder particle distribution at the nozzle exit.