Magnetic disk device and method for manufacturing magnetic disk device

A magnetic disk device comprising:

• a plurality of disk-shaped magnetic disks, each including a through-hole in a center section thereof;
• a spacer that is disposed among the magnetic disks and that includes a through-hole in a center section thereof;
• a hub inserted into the through-holes of the magnetic disks and the spacer;
• a clamp having a disk body portion, an annular flange portion having a distal surface and extending from the disk body portion, and a protrusion extending from the distal surface of the annular flange portion, the protrusion having a planar surface pressing and holding the magnetic disks and the spacer;
• and
• a plurality of fastening members, each fastening member of the plurality of fastening members fastening the clamp to the hub,
• wherein the clamp is fastened to the hub by the plurality of fastening members with a torque of from 5 cN·m to 45 cN·m;
• and
• a first contact length in a radial direction and defined by the planar surface between a first magnetic disk of the plurality of magnetic disks and the clamp is greater than or equal to ½ a second contact length in the radial direction and defined by contacting surfaces between the first magnetic disk of the plurality of magnetic disks and the spacer.