Molten
aluminium alloys have a tendency to coarsen their
grain structure at a high temperature. The degassing
operation also increases the grain size. The coarse
grain structure is not desired in a high quality casting
because it is responsible for lowering the mechanical
properties, creation of localised unsoundness &
cracking during forging and increasing the tendency
of hot tearing in the cast alloy.
A
fine grain-structure can be achieved by the introduction
of PMC Grain Refiner-1 which
incorporates a combination of suitable grain refining
elements.
PMC
Grain Refiner - 1 is
a white crystalline powder in tablet form. The grain
refining action is based on the combined nucleating
power of titanium and boron compounds on all aluminium
alloys with the exception of high conductivity aluminium.
100
to 200 grams per 100 kg melt.
10
tablets of 50 gram, 2 tablets of 500 gram,each are
rolled in moisture proof aluminium foil. These rolls
are further packed in 20 kg carton or in 50 kg polylined
fibre drums.
Use
hand gloves while handling fluxes. Avoid
inhalation of fumes, when treating metal. Ensure
adequate ventilation. Wash
hands with soap and water after handling.
These
instructions are given only for grain refining
treatment. For other fluxing treatment,
please refer to the corresponding PMC flux
literature.
Pre
heat the plungers and furnace tools which
are suitably coated to avoid iron pick-up.
Adjust
furnace conditions to bring the metal temperature
to approximately 750°C.
When
the pyrometer indicates that the temperature
is falling, aside a portion of the PMC Coverflux
and plunge half of the recommended amount
of PMC
Grain
Refiner
- 1. The remainder amount of the PMC Grain
Refiner-1 should be used after the reaction
has subsided.
Remove
the plunger, when the turbulance in the
melt ceases, keeping the protective layer
of PMC Cover flux intact.
The
metal is now ready for further treatment
prior to drossing off.
Ensure
that PMC Fluxes are kept in sealed condition in
a dry hot place.
Do
not allow PMC Fluxes to be exposed to the atmosphere
when not in use.
