A sealed head disk assembly having a base casting that provides attachment
points for major components of the head disk assembly and a cover for
enclosing major components of the head disk assembly. The base casting
has a hermetic seal encompassed by an outer perimeter of the base
casting. The hermetic seal is juxtaposed to at least one complementary
surface on the cover. The cover has a semi-hermetic seal inside a
perimeter of the complementary surface for the hermetic seal. The
semi-hermetic seal is juxtaposed to at least one complementary surface on
the base casting. The sealed head disk assembly includes a screw causing
deflection in a zone of the cover and provides spring force allowing
registering the hermetic seal against a complementary surface of the
hermetic seal on the base casting and the semi-hermetic seal against the
complementary surface of the semi-hermetic seal on the base casting.