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METALWORKING EQUIPMENT
AND TOOLS
metals is based on densification by the
mechanism of liquid phase sintering due
to the melting of the fusible component
in the powder mixture. In the latter
embodiment, compaction occurs due to
complete melting and melt spreading. It
is worth noting that such a classification
is not universal.
The process of direct laser sintering
of metals is characterized in that instead
of the polymer, alloys or compounds
with a low melting point are used, while
there is no such technological operation
as impregnation. The DMLS concept
was based on the German company
EOS GmbH, which in 1995 created a Fig. 2. Indirect Metal Laser Sintering − IMLS
commercial installation for direct laser
sintering of a steel-nickel bronze powder
system. The production of various products,
including ship fittings, by the DMLS method is based on the flowing of the formed melt-bundle
into voids between particles under the action of capillary forces. At the same time, for a successful
process, compounds with phosphorus are added to the powder mixture, which reduce the
surface tension, viscosity and oxidation state of the melt, improving wettability. The powder
used as a binder, usually has a smaller size than the base powder, as this allows you to increase
the bulk density of the powder mixture and accelerate the formation of the melt.

Fig. 3. Ship fittings

With selective laser melting of metals such as aluminum, copper, gold, an important issue
is their high reflectivity, which determines the use of a powerful laser system. However, increase
in the power of the laser beam adversely affects the dimensional accuracy of the product, since
with excessive heating the powder will melt and sinter outside the laser spot. A high laser power
leads to a change in the chemical composition because of metal evaporation, which is especially
characteristic for alloys containing low-melting components and having a high vapor pressure.
Fig. 1. Selective Laser Sintering − SLS In the case of residual porosity, it is necessary to apply additional technological operations

to increase the density of the product. Powder metallurgy methods such as sintering or hot

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