  In laser metal deposition (LMD) the height of the deposited track can vary
within and between layers, causing significant deviations during the process
evolution. Previous works have shown that in certain conditions a
self-stabilizing mechanism occurs, maintaining a regular height growth and a
constant standoff distance between the part and the deposition nozzle. Here we
analyze the link between the powder catchment efficiency and the deposition
height stability. To this purpose, a monitoring system was developed to study
the deposition in different process conditions, using inline measurements of
the specimen weight in combination with the layer height information obtained
with coaxial optical triangulation. An analytical model was used to estimate
the deposition efficiency in real-time from the height monitoring and the
process parameters, which was verified by the direct mass measurements. The
results show that the track height stabilization is associated to a reduction
of the powder catchment efficiency, which is governed by the melt pool relative
position with respect to the powder cone and the laser beam. For a given set of
parameters, the standoff distance can be estimated to achieve the highest
powder catchment efficiency and a regular height through the build direction.
