Real-time laser cladding control with variable spot size

Abstract

Laser cladding processing has been used in different industries to improve the surface properties or to reconstruct damaged pieces. In order to cover areas considerably larger than the diameter of the laser beam, successive partially overlapping tracks are deposited. With no control over the process variables this conduces to an increase of the temperature, which could decrease mechanical properties of the laser cladded material. Commonly, the process is monitored and controlled by a PC using cameras, but this control suffers from a lack of speed caused by the image processing step. The aim of this work is to design and develop a FPGA-based laser cladding control system. This system is intended to modify the laser beam power according to the melt pool width, which is measured using a CMOS camera. All the control and monitoring tasks are carried out by a FPGA, taking advantage of its abundance of resources and speed of operation. The robustness of the image processing algorithm is assessed, as well as the control system performance. Laser power is decreased as substrate temperature increases, thus maintaining a constant clad width. This FPGA-based control system is integrated in an adaptive laser cladding system, which also includes an adaptive optical system that will control the laser focus distance on the fly. The whole system will constitute an efficient instrument for part repair with complex geometries and coating selective surfaces. This will be a significant step forward into the total industrial implementation of an automated industrial laser cladding process

Direct Generation of High-Aspect-Ratio Structures of AISI 316L by Laser-Assisted Powder Deposition

“…The application of LMD in industry has experienced significant development in the last two decades [ 1 , 2 ]. The expansion of LMD involves many areas, such as optimization of process parameters [ 7 , 8 ], simulation [ 9 , 10 , 11 ]; studies of online control of the LMD process which have in consideration the control of laser powder [ 12 ] or the temperature in the melt pool [ 13 ], material microstructure [ 6 , 14 ] and mechanical response of the consolidated structure, as well as the behavior of the combination between the deposited material with the substrate, in which the material forms the coating [ 15 , 16 ].…”