Browse Prior Art Database

Methods of Eliminating Magnetic Brush Shaft Wear

IP.com Disclosure Number: IPCOM000060325D
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

Bhushan, B: AUTHOR [+4]

Abstract

The problem of wear of a printer magnetic brush shaft at the ball bearing/shaft interface is of concern. The mechanism of initiation of wear is electrical arcing. The following methods are suggested to eliminate the arcing: 1) block the path of current flow at the point of obvious wear, 2) provide an alternate (low impedance) path for current flow, and 3) interfere with the voltage-generating mechanism. The first approach is to insert a layer of insulating material between the shaft and bearing. A temporary solution is to apply an insulating elastomer between the two parts. This approach has the added advantage of damping out vibrations which could lead to fretting.

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 59% of the total text.

Page 1 of 2

Methods of Eliminating Magnetic Brush Shaft Wear

The problem of wear of a printer magnetic brush shaft at the ball bearing/shaft interface is of concern. The mechanism of initiation of wear is electrical arcing. The following methods are suggested to eliminate the arcing: 1) block the path of current flow at the point of obvious wear, 2) provide an alternate (low impedance) path for current flow, and 3) interfere with the voltage-generating mechanism. The first approach is to insert a layer of insulating material between the shaft and bearing. A temporary solution is to apply an insulating elastomer between the two parts. This approach has the added advantage of damping out vibrations which could lead to fretting. A second possibility is to roughen the shaft surface by sand blasting and then to apply a plasma-spray-coated layer of an insulating material, with perhaps a sub-coat for adhesion, to the magnetic shaft, along the area around the bearing. The preferred material is Cr2O3 . Since it has good wear resistance, it would minimize any wear in case of any wear debris or contamination at the interface. Fig. 1 shows the area (region A) which had worn away on the old, uninsulated shaft. We know that the electrostatic field gradient would be high at the point of discontinuity in the surface (a sharp edge) and thus arcing would be more likely to take place. Therefore, we removed the discontinuity at region B (Fig. 1) by having a radius at the edge. Alternatively, we...