  Directed Energy Deposition (DED) processes offer one of the most versatile
current techniques to additively manufacture and repair metallic components
that have generatively designed complex geometries, and with compositional
control. When compared to powder bed fusion (PBF), its applicability and
adoption has been limited because several issues innate to the process are yet
to be suitably understood and resolved. This work catalogs and delineates these
issues and anomalies in the DED process along with their causes and solutions,
based on a state-of-the-art literature review. This work also serves to
enumerate and associate the underlying causes to the detrimental effects which
manifest as undesirable part/process outcomes. These DED-specific anomalies are
categorized under groups related to the part, process, material, productivity,
safety, repair, and functional gradients. Altogether, this primer acts as a
guide to best prepare for and mitigate the problems that are encountered in
DED, and also to lay the groundwork to inspire novel solutions to further
advance DED into mainstream manufacturing.
