Application of Glass banding Tape on Armature?

A Simple Procedure Familiar To Anyone experienced in DC motor or generator repair, armature banding is used on other types of machines as well (such as wound-rotor motors) whenever a rotating winding must be held in position. Simple-yet the stress/strain relationships involved are complex and often misunderstood.

The sole purpose of end turn banding is to prevent outward flexing of the coils under the influence of centrifugal force. INTAF Polyglass Glass Fibre Banding Tape is therefore applied under tension to exert an inward compressive force on the end turns. If that inward force exceeds the outward force caused by rotation, the coils cannot move.

In some DC machines, steel wire banding plays a necessary role in the electromagnetic design. More often, however, during DC machine rewinding (and for all wound-rotor machines), wire banding can be replaced economically by glass tape. Comparing the size and number of turns of wire with the strength ratings of glass tape allows fairly simple conversion from one type of band to the other.

Banding design principles for those occasions when a tape band must be designed without the possibility of such a comparison, some understanding of the design principles may be helpful.

Obviously, the band must be strong enough to withstand the stress imposed by centrifugal force on the end turns. Tape strength in a finished band is a function of both temperature and initial tension

Two other concerns affect band design and placement. First, the band must not be too loose. Besides outward movement of coils at full speed, another consequence is inadequate seating against Inner coil supports.

On the other hand, too tight a band imposes internal stresses on coils and insulation that can lead to premature failure.

Great care must be taken to be sure that coils are not overstressed by the pressure of the band.

Two of the goals of banding are :

1. Coil movement is restrained, and
2. the band is obviously quite strong enough to withstand the hoop tension created by centrifugal force on those coils

Judgment and experience must be combined with an understanding of the stress/strain relationships involved.