disk lasers, a focus as small as about 0.2mm.
In addition to the laser beam source, another
decisive factor is that the machine has a
rotational axis that permits high speeds.
Depending on component size, Trumpf has
various laser machines that are candidates for
EHLA. The TruLaser Cell 3000 is suitable for
small and medium-sized components, while
the machines in the TruLaser Cell 7000 Series
are suitable for large ones. Apart from these
turnkey systems, manufacturers can integrate
the EHLA method into their existing systems.
The DepositionLine technology package from
TRUMPF can also be equipped with powder
feed nozzles developed by Fraunhofer ILT.
Looking forward Goebel says: “We are
looking down several avenues. Of course,
we are trying to be more productive. Going
faster is de nitely a goal for us, but what
we’d really like is to have the high-speed laser
cladding process in operation in as many
applications as we see. And we of course try
to enhance our system equipment so that
the process will get even more exible, for
instance being able to do some high-speed
cladding even on a 90° angle which is right
now not feasible. So, in short: getting faster,
more productive, more production, getting
into more applications and enhancing our
system technology.”
These kinds of hydraulic
components are ‘hard chromed’,
which is achieved by electroplating.
However, there are environmental concerns
associated with disposal of the plating solution.
EHLA is seen as a viable alternative.
“The advantage over hard chrome is you
can deposit very thin layers from 50m up to
several millimetres, but usually we are ne with
200 or 300m,” explains Goebel. “By doing that
and by having a large selection of alloys which
you can use and deposit on the material, which
are ready to use and are nearly all quali ed, you
can create metrologically dense, di usion dense
layers to provide perfect corrosion and wear
resistance that can be combined together and
this is, for us, a very interesting new technology
to look into where we can use our lasers and
our expertise in the material process.”
Yet another advantage, Goebel says, is that
the bonding strength of the
coating will usually be at
least on the same level
as the substrate. For
example, a steel
substrate could
be coated in steel
powder, it will have
the tensile strength
of steel, so it will
be extremely hard to
remove. Metals that are
considered too soft for certain
applications – for example 316L
stainless steel, which is austenitic – can also be
hardened by around 50% due to EHLA’s rapid
heating and cooling cycles. No extra chemicals
are used to do this, and any powder overspray
can be recycled and used again.
“Of course, there are certain limits,”
says Goebel. “Steel and titanium will not go
together. But we can use nearly every metal
which is available as a powder for that process.
We are still qualifying new materials.”
Available EHLA systems
Candel-Ruiz adds: “Our diode lasers and our
disk lasers are suitable for EHLA, depending
on the laser focus required.” With diode
lasers, a focus of around 1mm is possible; with
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