8.5x20mm Coreless Micro Motor 4pcs.

Coreless DC motors are a special type of DC motor which, as the name suggests, do not have an iron core in the rotor. Instead, a copper wire winding in basket form (coil) rotates around the outside of a cylindrical magnet. This has several advantages. Coreless motors can be built much more compactly than conventional DC motors, as the mechanism is much more space efficient. Since there is no iron core, the motor core has much less mass and can therefore accelerate and decelerate much faster and reach extremely high speeds. The absence of an iron core in the rotor prevents the cogging torque caused by magnetic induction; hence the rotation is smooth, with minimal noise and vibrations. Of course, there are not only advantages with coreless motors. Since the motors are very compact and can reach extremely high speeds, there is a risk of overheating. Therefore, coreless motors are less suitable for applications where they run continuously for a long time.