ELECTRIC POWERTOOL CARBON BRUSHES

Today, home appliances have been used every where. General speaking, almost every home appliances need to use the carbon brush as one of the most important parts. Such as: mill engine, mixing machine, electric shaving, electric hair clipper, air-drying machine, cleaner, right angle grinder, electric hammer, electric drill, cutting machine, grindstone wheel machine, edge trimmer, lig saw, electric pick, churn drill, culture starter machine, hot air heater, mowing machine and cine projector, etc. Beside these, rock drill, sandblasting machine, electric dig for woodworker and cutting groove machine also have been gradually popular.

Almost every electric motor for these power tool are 100 volt AC power universal motor. Considering the electric motor's efficiency we should think much of the handiness extent. So it's characteristics is minitype, high speed and high torque. We must add more circles for the winding because of design and economy. So ill commutation is permitted. It is only an exception like the umbrella electric motor's no spark commutation. Besides, there are some reasons to bring the commutation spark such as: bad commutator surface, off center axes, the wrong carbon brush position and out of place between brush holder and commutator, etc, which is characteristic of small electric motors.

It is very ease to adjust the speed because the power tool use the series excited motor. But the electric motor will bring low the torque when we use the resistance or transformer to regulating speed. More and more electric motor have been applied the electronic to control the speed to improve the status. The life of carbon brush will be shorter than the complete wave commutation if we use the cheap half wave commutation. So which is a question for us.

The life of carbon brush for small electric motor is shorter than the umbrella electric motor. But the life of the home appliance is also short. So one pair carbon brush can use for several years. It is no need to change the carbon brush in the electric appliance service life.

We generally apply electro graphite carbon brushes which possess low attrition coefficient and high brush contact drop. But to the very ill commutation electric motor we can use the high resistance natural graphite carbon brush which use the resin as agglomerant.