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|THE CASTING PROCEDURE (2)|
|V. Ryan © 2003-2022|
|TEMPERATURE CONTROL - Judging the temperature of the molten aluminium is sometimes difficult. Using a pyrometer, the instrument used for testing temperature, allows accurate measurement. The pyrometer is first warmed over the furnace to evaporate any moisture and then it is placed into the molten metal The temperature can be read on the meter, near the handle.|
|REMOVE ‘DROSS’ (WASTE) FORMED DURING HEATING THE ALUMINIUM - When the temperature reaches 650 degrees it is ready for pouring but first the ‘dross’ (waste that collects on the surface of the aluminium) must be removed with a special tool.|
|CRUCIBLE LIFTED OUT OF
FURNACE - The sliding lid/top of the furnace is pulled back
using a steel hook. This allows special lifting tongs to be placed
around the crucible which can then be lifted up and away from the
furnace. The crucible is set to rest in a bed of sand which surrounds
the furnace. The crucible should never be allowed to rest directly on a
the cold concrete floor as this could cause an explosion.
This process should never be carried out by a pupil. Great care is needed as the molten aluminium is at a very high temperature.