Abstract A method for fabricating magnetically responsive circular discs to store magnetically encoded information is disclosed. The faces of rough finished circular discs of ceramic material are ground to a predetermined degree of flatness and mutual parallelism. A centrally located recess is ground in at least one of the faces whereby the perimeter of the recess defines a circular band extending radially outwardly to the edge of the disc. The recess of the disc is coated with a magnetically responsive material to a thickness at least equal to the depth of the recess. Alternately, a coating of magnetically responsive material may be formed across the whole surface of each recessed face. Each recessed face is ground with a grinding medium acting only upon the magnetically responsive material until the coating is essentially flush with the surface of the circular band.
A method for fabricating, from a rough ceramic casting, a circular disc carrying a magnetic medium coating on one or both faces thereof for storing information, the method comprising the steps of: A. finishing the faces to a predetermined tolerance of flatness and mutual parallelism; B. grinding a recess in at least one face, which recess is concentric with the axis of the disc and terminates short of the disc periphery to form a raised circumferential band about the outer portion of the face; C. coating the recessed area and raised circumferential band with a coating of magnetic material; and, D. surface grinding the face utilizing a grinding medium which will work the coating of magnetic material, but not the ceramic material; whereby the coating of magnetic material is ground substantially flush with the circumferential band in the recess and is removed from the surface of the circumferential band.
Claim 2
Independent Claim
149 words
A method for fabricating, from a rough ceramic casting, a circular disc carrying a magnetic medium coating on one or both faces thereof for storing information, the method comprising the steps of: A. finishing the faces to a predetermined tolerance of flatness and mutual parallelism; B. grinding a recess in at least one face, which recess is concentric with the axis of the disc and terminates short of the disc periphery to form a raised circumferential band about the outer portion of the face; C. coating the recessed area and raised circumferential band with a coating of magnetic material; and, D. surface grinding the face utilizing a grinding medium which will work the coating of magnetic material, but not the ceramic material; whereby the coating of magnetic material is ground substantially flush with the circumferential band in the recess and is removed from the surface of the circumferential band.
Claim 3
Dependent Claim
22 words
The method as set forth in claim 1 wherein steps B, C and D are performed on both faces of the disc.
Claim 4
Dependent Claim
35 words
The method as set forth in claim 1 including the step of cleaning the ceramic disc after completion of step B and a further step of cleaning the composite disc on completion of step D.
Claim 5
Dependent Claim
31 words
The method as set forth in claim 1 including a step of reguLating said grinding step to grind a recess of a depth equivalent to a predetermined thickness of the coating.