Why slot fill factor is critical in motor design and how multiple wires affect it.

Slot fill factor is the ratio of bare copper area compared to the total available area within the iron stator slot. A higher fill factor means a more powerful, efficient motor within the same physical frame.

Hand-winding a motor rarely achieves the extremely high fill factors of robotic factory winders. Therefore, repair technicians must be strategic about wire placement and insulation thickness.

Using multiple smaller parallel strands instead of one thick wire is a classic trick to improve fill factor. The smaller wires shift and pack into the microscopic gaps that a large, stiff round wire would leave completely empty.