Method of forming a power tool
An electric motor has a stator in which an armature is disposed. The armature has a lamination stack having slots in which magnet wires are wound. An armature shaft extends coaxially through the lamination stack and a commutator is disposed on the armature shaft to which ends of the magnet wires are electrically coupled. The magnet wires are at least partially encased in thermally conductive plastic. When the thermally conductive plastic is molded, a balancing feature is formed of the thermally conductive plastic. In aspects, the balancing feature can include a layer of the plastic from which plastic can be removed during balancing; one or more balancing rings adjacent axial sides of the lamination stack from which plastic can be removed to balance the armature; or one or more balancing rings having one or more pockets therein in which one or more weights are disposed to balance the armature.
1. An electric motor, comprising:
a stator;
an armature disposed in the stator, the armature including:
a lamination stack having slots therein;
an armature shaft extending coaxially through the lamination stack;
a plurality of magnet wires wound in the slots of the lamination stack;
a commutator disposed on the armature shaft to which ends of the magnet wires are electrically coupled; and
plastic at least partially encasing the magnet wires with at least one balancing feature formed from the plastic.
2. The apparatus of claim 1 wherein the balancing feature includes a layer of the plastic from which a portion can be removed during dynamic balancing of the armature to balance the armature.
3. The apparatus of claim 1 wherein the balancing feature includes a layer of plastic having at least one balancing ring molded from which the portion of plastic can be removed during dynamic balancing, the at least balancing ring adjacent an axial end of the lamination stack.
4. The apparatus of claim 3 wherein the at least one balancing ring includes first and second balancing rings adjacent respective opposed axial ends of the lamination stack.
5. The apparatus of claim 4 wherein the balancing rings are located closer to bearing planes of the electric motor than respective opposed axial ends of the lamination stack.
6. The apparatus of claim 4 wherein the plastic is thermally conductive plastic.
7. The apparatus of claim 1 wherein the plastic is thermally conductive plastic.
8. The apparatus of claim 1 wherein the balancing feature includes one or more pockets therein for receiving one or more weights that are placed in the pockets during dynamic balancing of the armature to balance the armature.
9. The apparatus of claim 8 wherein the balancing feature includes at least one balancing ring molded adjacent an axial end of the lamination stack, the balancing ring including the one or more pockets.
10. The apparatus of claim 9 wherein the balancing ring includes a plurality of pockets therein.
11. The apparatus of claim 9 wherein the at least one balancing ring includes first and second balancing rings adjacent respective opposed axial ends of the lamination stack, each of the balancing rings including one or more pockets for receiving one or more weights that are placed in the pockets during dynamic balancing of the armature to balance the armature.
12. The apparatus of claim 11 wherein the balancing rings are located closer to bearing planes of the electric motor than respective opposed axial ends of the lamination stack.
13. The apparatus of claim 11 wherein the plastic is thermally conductive plastic.