Manufacturing method of magnetic disk device and magnetic disk device

1. A manufacturing method of a magnetic disk device comprising a plurality of magnetic disks integrally rotated, the plurality of magnetic disks having a plurality of recording surfaces, and a plurality of magnetic heads corresponding to the plurality of recording surfaces integrally moved in a radial direction of the plurality of magnetic disks,

wherein the manufacturing method includes

measuring an initial value of a clearance at a first position between a blank first recording surface among the plurality of recording surfaces and a first magnetic head corresponding to the first recording surface among the plurality of magnetic heads,

estimating a first distribution that is a distribution in the radial direction of an initial value of a clearance between the first recording surface and the first magnetic head based on the measured initial value of the clearance at the first position of the first recording surface,

recording a plurality of first spiral signals on the first recording surface by using the first magnetic head while controlling a clearance between the first recording surface and the first magnetic head by using first data that is the estimated first distribution,

measuring a second distribution that is a distribution in the radial direction of an initial value of a clearance between a blank second recording surface different from the first recording surface among the plurality of recording surfaces and a second magnetic head corresponding to the second recording surface among the plurality of magnetic heads under positioning control using the plurality of first spiral signals recorded on the first recording surface,

recording the plurality of first spiral signals on the second recording surface using the second magnetic head while controlling a clearance between the second recording surface and the second magnetic head using the measured second distribution, and

recording a plurality of second spiral signals on a third recording surface different from any of the first recording surface and the second recording surface among the plurality of recording surfaces using a third magnetic head corresponding to the third recording surface among the plurality of magnetic heads under positioning control using the plurality of first spiral signals recorded on the second recording surface.

2. The manufacturing method according to claim 1 further comprising:

measuring the first distribution under the positioning control using the plurality of first spiral signals recorded on the first recording surface;

comparing the first data with second data that is the measured first distribution; and

in a first case, executing recording the plurality of second spiral signals on the third recording surface using the third magnetic head under the positioning control using the plurality of first spiral signals recorded on the first recording surface, and in a second case where a deviation between the first data and the second data is larger than the first case, executing recording the plurality of first spiral signals on the second recording surface, and recording the plurality of second spiral signals on the third recording surface under the positioning control using the plurality of first spiral signals recorded on the second recording surface.

3. The manufacturing method according to claim 2 , wherein

the first distribution includes initial values of clearances at a plurality of different radial positions,

comparing the first data with the second data includes calculating a difference between an initial value of a clearance included in the first data and an initial value of a clearance included in the second data for each radial position, and

the first case is a case where all of the differences for each radial position are less than a threshold value, and the second case is a case where at least one of the differences for each radial position exceeds the threshold value.

4. The manufacturing method according to claim 1 further comprising:

measuring a third distribution that is a distribution in the radial direction of an initial value of a clearance between the third recording surface and the third magnetic head under the positioning control using the plurality of first spiral signals recorded on the first recording surface,

wherein recording the plurality of second spiral signals on the third recording surface using the third magnetic head includes recording the plurality of second spiral signals while controlling the clearance between the third recording surface and the third magnetic head using the measured third distribution.

5. The manufacturing method according to claim 2 further comprising:

measuring a third distribution that is a distribution in the radial direction of an initial value of a clearance between the third recording surface and the third magnetic head under the positioning control using the plurality of first spiral signals recorded on the first recording surface,

wherein recording the plurality of second spiral signals on the third recording surface using the third magnetic head includes recording the plurality of second spiral signals while controlling the clearance between the third recording surface and the third magnetic head using the measured third distribution.

6. The manufacturing method according to claim 3 further comprising:

measuring a third distribution that is a distribution in the radial direction of an initial value of a clearance between the third recording surface and the third magnetic head under the positioning control using the plurality of first spiral signals recorded on the first recording surface,

wherein recording the plurality of second spiral signals on the third recording surface using the third magnetic head includes recording the plurality of second spiral signals while controlling the clearance between the third recording surface and the third magnetic head using the measured third distribution.

7. The manufacturing method according to claim 1 further comprising:

recording a plurality of third spiral signals on a fourth recording surface different from any of the first recording surface, the second recording surface, and the third recording surface among the plurality of recording surfaces by using a fourth magnetic head corresponding to the fourth recording surface among the plurality of magnetic heads under positioning control using the plurality of second spiral signals recorded on the third recording surface.

8. The manufacturing method according to claim 2 further comprising:

recording a plurality of third spiral signals on a fourth recording surface different from any of the first recording surface, the second recording surface, and the third recording surface among the plurality of recording surfaces by using a fourth magnetic head corresponding to the fourth recording surface among the plurality of magnetic heads under positioning control using the plurality of second spiral signals recorded on the third recording surface.

9. The manufacturing method according to claim 3 further comprising:

recording a plurality of third spiral signals on a fourth recording surface different from any of the first recording surface, the second recording surface, and the third recording surface among the plurality of recording surfaces by using a fourth magnetic head corresponding to the fourth recording surface among the plurality of magnetic heads under positioning control using the plurality of second spiral signals recorded on the third recording surface.

10. The manufacturing method according to claim 4 further comprising:

recording a plurality of third spiral signals on a fourth recording surface different from any of the first recording surface, the second recording surface, and the third recording surface among the plurality of recording surfaces by using a fourth magnetic head corresponding to the fourth recording surface among the plurality of magnetic heads under positioning control using the plurality of second spiral signals recorded on the third recording surface.

11. The manufacturing method according to claim 5 further comprising:

recording a plurality of third spiral signals on a fourth recording surface different from any of the first recording surface, the second recording surface, and the third recording surface among the plurality of recording surfaces by using a fourth magnetic head corresponding to the fourth recording surface among the plurality of magnetic heads under positioning control using the plurality of second spiral signals recorded on the third recording surface.

12. The manufacturing method according to claim 6 further comprising:

recording a plurality of third spiral signals on a fourth recording surface different from any of the first recording surface, the second recording surface, and the third recording surface among the plurality of recording surfaces by using a fourth magnetic head corresponding to the fourth recording surface among the plurality of magnetic heads under positioning control using the plurality of second spiral signals recorded on the third recording surface.

13. The manufacturing method according to claim 1 , wherein

the plurality of first spiral signals is a first number of first spiral signals,

the plurality of second spiral signals is a second number of second spiral signals, and

the second number is larger than the first number.

14. The manufacturing method according to claim 2 , wherein

the plurality of first spiral signals is a first number of first spiral signals,

the plurality of second spiral signals is a second number of second spiral signals, and

the second number is larger than the first number.

15. The manufacturing method according to claim 3 , wherein

the plurality of first spiral signals is a first number of first spiral signals,

the plurality of second spiral signals is a second number of second spiral signals, and

the second number is larger than the first number.

16. The manufacturing method according to claim 4 , wherein

the plurality of first spiral signals is a first number of first spiral signals,

the plurality of second spiral signals is a second number of second spiral signals, and

the second number is larger than the first number.

17. The manufacturing method according to claim 7 , wherein

the plurality of first spiral signals is a first number of first spiral signals,

the plurality of second spiral signals is a second number of second spiral signals, and

the second number is larger than the first number.

18. The manufacturing method according to claim 7 , wherein

the plurality of first spiral signals is a first number of first spiral signals,

the plurality of second spiral signals is a second number of second spiral signals,

the plurality of third spiral signals is a third number of third spiral signals,

the second number is larger than the first number, and

the third number is larger than the second number.

19. A magnetic disk device comprising:

a plurality of magnetic disks integrally rotated and having a plurality of recording surfaces;

a plurality of magnetic heads corresponding to the plurality of recording surfaces;

an actuator system that integrally moves the plurality of magnetic heads in a radial direction of the plurality of magnetic disks; and

a controller configured to

measure an initial value of a clearance at a first position between a blank first recording surface among the plurality of recording surfaces and a first magnetic head corresponding to the first recording surface among the plurality of magnetic heads,

estimate a first distribution that is a distribution in the radial direction of an initial value of a clearance between the first recording surface and the first magnetic head based on the measured initial value of the clearance at the first position of the first recording surface,

record a plurality of first spiral signals on the first recording surface by using the first magnetic head while controlling a clearance between the first recording surface and the first magnetic head by using first data that is the estimated first distribution,

measure a second distribution that is a distribution in the radial direction of an initial value of a clearance between a second recording surface different from the first recording surface among the plurality of recording surfaces and a second magnetic head corresponding to the second recording surface among the plurality of magnetic heads under positioning control using the plurality of first spiral signals recorded on the first recording surface,

record the plurality of first spiral signals on the second recording surface using the second magnetic head while controlling a clearance between the second recording surface and the second magnetic head using the measured second distribution, and

record a plurality of second spiral signals on a third recording surface different from any of the first recording surface and the second recording surface among the plurality of recording surfaces using a third magnetic head corresponding to the third recording surface among the plurality of magnetic heads under positioning control using the plurality of first spiral signals recorded on the second recording surface.

20. The magnetic disk device according to claim 19

wherein, the controller is further configured to

measure the first distribution under the positioning control using the plurality of first spiral signals recorded on the first recording surface,

compare the first data with second data that is the measured first distribution, and

in a first case, execute recording the plurality of second spiral signals on the third recording surface using the third magnetic head under the positioning control using the plurality of first spiral signals recorded on the first recording surface, and in a second case where a deviation between the first data and the second data is larger than the first case, execute recording the plurality of first spiral signals on the second recording surface, and recording the plurality of second spiral signals on the third recording surface under the positioning control using the plurality of first spiral signals recorded on the second recording surface.