Experimental and computational assessment of minimizing overfill in trajectory corners by laser velocity control of laser cladding

In the context of laser metal deposition (LMD), the problem of avoiding unintentional material accumulation in bead corners or bends is central. Most of the existing approaches to limit such an accumulation are expensive trial-and-error ones. This manuscript presents the experimental verification of a recently reported computational method for minimizing material overfill in corners in LMD. The verification consisted in the deposition of single-layer corners with angle θ∈{15∘,30∘,45∘,60∘,75∘} with (i) constant and (ii) controlled (as dictated by the computational minimization) tool-head velocity. The term controlled velocity in this manuscript refers to the fact that the nozzle velocity can be adjusted in advance with predefined parameters resulting from the simulations of variable velocities. The comparison between the predicted and experimental bead topographies cannot be executed via standard registration methods because these methods minimize the distance between the registered datasets. In response to this limitation, this manuscript presents a registration method that avoids overall distance minimization. This registration method is based on the sequential matching of datums between the experimental and predicted datasets. The results of the experiments revealed that (i) the computational minimization strategy is effective for reducing material overfill in LMD and (ii) near 40% of the metal powder delivered by the nozzle is wasted. This powder loss is a constant feature across LMD implementations and is not caused by the minimization of metal overfill at corners. These facts show that (i) voxel-based modeling is an effective tool for bead topography and mass/area-based bead computations and (ii) LMD is useful for the cladding stage but not for the production of the bulk piece. Additional work is required to appraise the effective (i.e., not nominal) powder rate deposited at the bead. Future efforts will be dedicated to extend the material overfill minimization strategy to multi-layer deposition.