3849b6c8__and_Decker_Drill____GICL_Wiki__Reason_for_Material_Selection
[Part Name] Inner Motor Component [Quantity] 1 [Model Number] 385537-02 052105-XP, KG16 [Description] shaft with cooling fan,plastic insulation under ball of copper wire with metal plates, green resin insulation, copper cylinder over a plastic cylinder, holes in end of shaft, gear teeth at one end [Function] Fan to cool motor, helps to convert the electrical to mechanical power , connects to gear assembly [Material] Copper, steel , laminate, plastic,and resin [Reason for Appearance] Design to fit into outer motor, balanced design, generates air flow [Manufacturing Process] Sheet Metal Forming, Extrusion, Machining [Reason for Material Selection] 
high conductivity, high strength, cheap easy to produce,and holds everything together
Difference between revisions of "Group 12 - Black and Decker Drill" - GICL Wiki