the passage of the armature bodies 10 through the chamber 31 is represented by the arrow 20 the grounding of the armature bodies 10 is effected via the conveyor belt 22 which has clamping devices 23 and is in turn grounded a spray apparatus 32 is integrated with the chamber 31 and via at least one spray location 33 by means of compressed air sprays a metered quantity of powder onto each armature body 10 to that end a so called spray gun or corona gun is disposed at each spray location 33 and its spraying direction is aimed at the particular armature body 10 moving past it such spray guns are available on the market as standard components and are used for instance in painting decorative surfaces the spray guns are connected to a voltage potential of approximately 70 kv for the sake of electrically charging the powder particles the quantity of powder sprayed per armature body 10 is metered such that a layer thickness of preferably 1 0 to 1 5 mm is created on the armature body 10 a coarse plastic powder is used whose powder particles have a mean diameter of more than 150 u03bcm these heavy powder particles improve the overcoming of the faraday effect mentioned above and lead to an improved uniform coating of the slot walls of the axial slots 14 in the armature body 10 powder that does not reach the armature bodies 10 is delivered via a so called u201c overspray u201d line 34 to a powder bin 36 in which the compressed air laden with powder particles is passed through filters and flows out into the environment as waste air arrow 37 the powder particles trapped by.