The slip ring, being the key component of the instrument and equipment, tends to be worn when it works under the influence of many factors. The friction and wear characteristics of the contact material of slip rings are analyzed simply as below.
1. The friction coefficient of the two contact parts decreases with increasing loading on contacts, and is stable finally. As the loading is greater than a certain value, the friction coefficient tends to be slightly magnified with an increasing current. The wear rate of conducting rings is increased as the current becomes greater. When the current rises to a certain value, the wear rate of materials shows a “U” shape change of minimizing first and then enlarging with an increasing load. As to the contact resistance of friction pairs, it becomes smaller as the loading is enlarged, and keeps a fixed value finally.
2. There exists a proper contact loading between friction pairs, around which the wear rate of the contact material is relatively small, so are the friction coefficient between friction pairs and contact resistance. With such a load, the electrical slip ring shows an excellent performance. However, the proper contact loading varies with different contact materials.
3. Wears of friction pairs mainly focus on the conducting rings, with the supplement of brush filament. When operating, the conducting rings have adhesive wear, abrasive wear and arc erosion. Under a low contact loading, adhesive wear is the main form with a slight mechanical wear. At this time when the current is relatively large, electric wear takes the main wear form, and relatively serious arc erosion in the conducting rings will occur. However, under a high contact loading, the main wear is the mechanical form with a comparatively weak electric wear. Abrasive and adhesive wear happens mainly in the electric rings.