The air gap of a motor is the gap between the stator teeth or core and the rotor magnets. This gap is a key component in the motor design, and affects the overall strength of the magnetic circuit and motor efficiency.
The standard air gap in an electric motor is typically about 0.020-0.050 inches. In most design processes, there is give-and-take to the amount of air gap designed into the motor. A wider air gap increases the rotor-stator alignment tolerances, easing installation. However, a wider air gap leads to a weaker magnetic circuit and will reduce the efficiency of the motor. This is detrimental to applications such as surgical robotics, exoskeletons, and satellite communications, where high torque output is required in a compact form-factor.
Motor design engineers are tasked with balancing these effects, to provide a motor that offers both high torque density and ease of installation.
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