Armature Shafts: Creepage Band and Banding

You will probably need to do some additional research in order to make sure that you and your customers are talking about the same thing. I believe these are terms that are slightly open to interpretation. But to help explain better, I offer the following:

I believe that the term "creepage band" refers to an insulated area around the conductive surfaces of the commutator. This most likely includes any raised insulator edges between the conductive rings which may be prone to chipping or breaking since they have a larger outside diameter than the commutator rings.

The ability of electricity to jump a gap (in air) is nearly a constant. But when electricity is applied between two conductors that are in contact with a surface, any contaminates or the surface itself, presents a potentially lower resistance path and thus the jump distance is reduced. The term "Creepage" seems to assume that the surface conditions will remain constant. I don't like the term because we all know that surfaces are always subject to change. So, it may only be useful in describing the "as manufactured" term. Consequently, it is not a very good measure of performance of the insulator under any and all conditions.

The term Banding refers to the actual construction of the clusters of wire (or coils) that need to keep within a given geometrical tolerance. The rotor and stator must work together to generate the required magnetic field strength, without entanglement. So, the coils must be tight and stay in position at all times. And the coil can be thought of as a single fixed "band" of material, unless its geometry or some other attribute is disturbed.

There are no specific standard tests or instruments that everyone uses for measuring creepage because it involves a number of variables that are different from one case to another. And you may find that one place will define it carefully, but in a way that can not be tested repeated somewhere else. Consequently, you may encounter conflicting definitions.

I know these answers may not have been as exact as you were hoping, but know that some of it depends upon whom you are asking.