Make A Brushless Motors More Efficient

The most recent advancement in power tools is brushless motors. But what exactly is a brushless motor, and why should you use one? To gain a better understanding of this new technology, let’s look at the present technology: brushed motors.

An electric motor has permanent magnets (stator) on the outside and a rotating armature (rotor) on the inside.

The rotor has an electromagnet. As energy passes through the rotor, the electromagnet creates a magnetic field that attracts and repels the permanent magnets in the stator. To make the motor spin 360°, however, the polarity of the electromagnet must be changed, which is accomplished by a pair of brushes.

Instead of brushes, motor brushes are small carbon blocks linked to a compression spring. Brushes are forced against the rotating electrodes of the rotor. As the electromagnet spins, the brushes modify the magnetic polarity.

Brushed motors are dependable, generally efficient, and inexpensive to manufacture, but they have a number of disadvantages. For instance, carbon brushes eventually wear out and must be replaced. As the motor operates, the brushes are constantly breaking and establishing electrical contact, creating sparking and noise.

The friction caused by the brushes rubbing against the spinning rotor causes the motor to run hotter. Brushes also limit the top-end speed of the motor. For these and other reasons, prominent tool manufacturers, such as Rockwell, have introduced brushless motors to their portable power tool lines.

A brushless motor has no brushes and is turned inside out, with the permanent magnets attached to the rotor and the electromagnets attached to the stator. While the motor turns, the electromagnets are charged by a computer coupled to high-power transistors, effectively replacing the brushes.

Brushless motors provide various advantages over equivalent brushed motors, including no brushes to wear out or replace, quieter and cooler operation, no electrical sparking, and up to 50% longer runtime for cordless tools.

Because it is electronically regulated, a brushless motor also provides the perfect amount of power for the work. For example, the motor can identify whether you’re drilling a 1/8-inch hole in drywall or a 2-inch hole in a steel door and adjust the torque accordingly (power). Brushed motors, on the other hand, run at a maximum speed no matter what the duty is.

Okay, I see what you’re thinking: brushless motors are simply too amazing to be true; there must be a catch somewhere. Although there isn’t a catch, brushless motors do have one drawback: they are much more expensive to make than normal brushed motors. Because of the tool’s greater efficiency and longer life, the initial investment is typically recouped.

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