Abstract: A magnetic disk cartridge is provided with a dust shutter which is slidably mounted on a casing to open and close a magnetic head access opening in the casing . A V-shaped shutter spring for urging the dust shutter toward the closing position is inserted into the casing through a spring insertion opening. A magnetic disk cartridge assembly system includes a guide member which has a guide groove for holding the shutter spring in a compressed state and is adapted to bring a first end of the guide groove in close opposition to the spring insertion opening of the casing, the width of the guide groove being not larger than that of the spring insertion opening at least at the first end, and a pusher which is adapted to move the spring along the guide groove and to insert it into the spring insertion opening through the first end of the guide groove.

Abstract: A magnetic disk cartridge comprises a hard case, a magnetic disk sheet rotatably housed in the hard case, and a disk-shaped or polygonal liner disposed between the magnetic disk sheet and an inner wall surface of the hard case for cleaning the recording surface of the magnetic disk sheet. Internal peripheral wall sections at corners of the hard case are formed by linear portions conforming with the outer shape of the polygonal liner, and curved portions conforming with the outer shape of the disk-shaped liner.

Abstract: A method of manufacturing a liner for a magnetic disk which is formed of non-woven fabric and has a predetermined width, a predetermined length, a central opening and contoured four corners comprising steps of supplying a plurality of non-woven fabric strips, each having a width substantially equal to the width of the liner to be formed, in a stacked state, stamping out openings in the stacked non-woven fabrics, cutting the portion of the stacked non-woven fabrics corresponding to the contoured four corners of the liners to be formed, simultaneously with the stamping of the openings, subsequently separating the non-woven fabric strips and cutting the leading edge portion of the non-woven fabric strips into the predetermined length.

Abstract: A method and apparatus for assembling a front guard panel having two inwardly projecting shafts on rearwardly facing end pieces into two corresponding holes of a half case. The farther hole is open. The guard panel is placed on table which moves linearly with respect to the half case and is inclined with respect to the front of the half case. The linear movement places the near shaft adjacent the near hole. Then the guard panel is rotated about an axis near the near hole so as to insert the near shaft into the near hole and to move the far shaft into the far hole.