Browse Prior Art Database

Method for Determining Demagnetizing Effects of Particles

IP.com Disclosure Number: IPCOM000041690D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Pesch, JA: AUTHOR

Abstract

One source of contamination in a disk storage drive could be the bearing races which are made from stainless steel. Stainless steel is normally not magnetizable; however, when it is cold worked, it can be magnetized. Particles, micron in size, work loose from the bearing races and become a source of contamination. The amount of demagnetization caused by these particles can be measured by preparing a sample having the same length-to-thickness ratio as the contaminating particles. This is done by cutting a piece of material of the same composition as the contaminating particles and cold working the material into a wire. The wire 10 is then potted in a plastic mount 15 near the face thereof (Fig. 1). The plastic mount is polished smooth until the wire is flush with the face of the mount.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 91% of the total text.

Page 1 of 2

Method for Determining Demagnetizing Effects of Particles

One source of contamination in a disk storage drive could be the bearing races which are made from stainless steel. Stainless steel is normally not magnetizable; however, when it is cold worked, it can be magnetized. Particles, micron in size, work loose from the bearing races and become a source of contamination. The amount of demagnetization caused by these particles can be measured by preparing a sample having the same length-to-thickness ratio as the contaminating particles. This is done by cutting a piece of material of the same composition as the contaminating particles and cold working the material into a wire. The wire 10 is then potted in a plastic mount 15 near the face thereof (Fig. 1). The plastic mount is polished smooth until the wire is flush with the face of the mount. A magnetic field of sufficient magnitude to magnetize the wire is applied along the axis of the mounted wire. A sample of magnetic recording media 20 (Fig. 2) is magnetized along a specified direction and its magnetic moment along that direction is measured with a vibrating sample magnetometer. This sample is then moved along the polished surface of the mount so that the entire surface of the magnetic media is exposed to the field of the wire. Thereafter, the magnetic moment of the magnetic recording media is measured in the vibrating sample magnetometer. The change in magnetic moment is a measure of the demagnetizing effect...