FIRING
After isostatic or dry pressing and machining where required, the components
are fired in small batch or large intermittent kilns dependent upon
the material grade, size and quantity at temperatures up to 1750°C.
Very careful control of kiln temperature and atmosphere is required
if the components are to be of the correct microstructure for metallizing.
GRINDING
After firing, only processes employing diamond abrasives can produce
dimensional changes or improved surface finishes. Grinding, lapping,
honing and polishing are routinely employed to produce extremely close
control of dimensions and finishes.
It should be remembered that only certain features can be ground
and also that grinding using diamond abrasives adds significantly to
unit costs.
Features which cannot be machined after firing, such as hole pitches
or pitch circle diameters, will still be subject to the as-fired tolerance
of +/-1%. Continued on the next page.
|
