Die
Casting Coatings
Heat
checking is a common cause of failure in die casting dies made of
steel (i.e.: H-13) and is commonly attributed to the over stressing
or thermal fatigue of the steel used. This thermal fatigue is caused
by alternate heating and cooling of the surface of the steel die
in conjunction with the continuous thermal shocks caused during
the introduction of the molten die cast materials.
Pretreatment
of dies with the Armoloy® Process adds strength to the steel and
helps overcome damage already done. The process does not remove
the heat checks completely, but it does reduce the severity of existing
damage, holding it in check so further heat checking continues at
a much reduced rate.
The process
of die casting requires the rapid succession of heating and cooling
which causes heat checks. The die and castings produced get progressively
worse as the heat checks grow longer and penetrate deeper. Another
effect of the heat checks are cracks or cavitation from the die
surface into the steel. Costly and time consuming rework of the
dies result.
A most logical solution
might be to fill in these crevices with a strong material that would
not be easily washed away. This “crack filling” can
and is being done with Armoloy® coating. There is an optimum time
to process die casting dies – when the cracks are deep enough
to need filling but not so deep that they cannot be filled completely.
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