Custom built rotary hearth furnace Selection of crucibles and charge loader.
Carbolite can supply crucibles, cuples
and loading tools.
The furnace illustrated opposite is an
example of Carbolite's ability to custom design and build units tailored
to meet individual specifications. it shows a rotary hearth furnace
for the production of wedding rings using the powder metallurgy method.
It is used to sinter 'compacts' to provide strength and workability.
The compacts are formed from powders which are produced directly from
the molten state by passing the material through high pressure water
or gas jets. The powder is then packed into a die and pressed to form
a ring that has a rectangular cross section, known as a compact.
The furnace allows high throughput of compacts which
are loaded into trays holding several hundred at a time. After loading,
the furnace rotates by 10° to allow another tray to be loaded. The
speed of rotation can be adjusted to give sintering times of up to 24
hours. Process temperatures are between 750-800°C under an atmosphere
of 95% nitrogen and 5% hydrogen to prevent oxidation. Heating is provided
by 27 wire spiral resistance elements supported on ceramic tubes and
are separated into three control zones to provide furnace temperature
uniformity.
