|
|
Brush Bedding.
This is the process of accurately facing the brush contact face until it matches the curvature of the slipring or commutator. This procedure should not be under estimated because it is an important factor in enabling a Patina (skin) to form on the collector surface. The motor designer has gone to considerable trouble to calculate the size of brush required with regard to the area covered and the current being carried by the brush the commutator or the ring. Failure to bed the brushes in properly to the collector surface means that total area covered by the brush is reduced and it produces mechanical instability of the brushes, increasing the current density of the brush. All of these factors give rise to poor current collection. Judgment on the performance of the motor under these conditions is obviously misleading.
After the Brush Holders have been correctly fitted you must ensure that the bottom of each brush box is no more than 2.4 mm from the surface of the slipring or commutator then the next step is to fit the brushes in their boxes.
Like new machinery brushes must be bedded in before they can operate at their best. Bedding in shapes the running face of the brush to the same contour as the slipring or commutator. When the radius of the entire brush face matches the radius of the slipring or commutator you have the maximum contact area vital to give good electrical contact.
To bed the brushes in correctly we recommend using glass paper. A strip of glass paper slightly wider than the width of the brush is carefully placed between the ring and brush with the abrasive material towards the brush. Pull the abrasive strip back and forth underneath the brush until the brush contact face is of the same form and shape as the slipring surface.
We recommended that Abrasive Paper ( 80 grit ) is used for the initial bedding in. To finish off the bedding in process take a strip of fine Abrasive paper approx. (100 - 300 grit ) insert it under the brush and repeat the operation.
Ensure that you clean out any abrasive dust from the machine.
NOTE:- Do not use emery paper as it may cause short circuits. Use glass paper.
UpDated 20-03-2001