Brush bedding process for small commutator motors - employing chemical reaction between ammonium salt and carbon to remove excess brush material

摘要

The brush bedding process is to reduce the running in time required and hence improve on mass production output. The process is also applicable to sliprings. Bedding is achieved by chemical reaction. The surface of the commutator or brush is treated with an ammonium salt, for example ammonium phosphate or ammonium chloride. When the machine is first run the inevitable arcing at the brushes produces a plasma condition between brush and commutator in which the salts react with the brush material and form the brush to the smooth contour of the commutator. The reaction can take place in air of controlled humidity or in a special atmosphere of nitrogen or hydrogen. The process is such that the salts are finally sublimated and removed after the bedding process. A reduction in running in time from the present typical 30 min. to 1 hour down to 3 to 8 minutes can be achieved.