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 next page.