In the evolution of cordless power tools, there hasn’t been a greater development than the advancements made in the brushless motor.
Greater torque per weight, greater torque per watt, less noise, longer lifetime – for tradies and contractors around the world it’s simply a win, win, win.
The advancements of the brushless motor are the answers that users of cordless tools have been asking since the development of the system. Like all early technologies, it didn’t take very long for reductions in size, weight, and advancements in power, performance and runtime to kick in.
The introduction of electric power tools revolutionised the building industry in a dramatic way and once tradies observed and experienced the speed and subsequently increased productivity of these tools, there was no going back. Power was not a problem because most sites had electric power poles. If not, heavy duty generators were readily available. Weight was not considered a problem because the benefits far outweighed this disadvantage. ‘Ergonomic’ was a word foreign to the tool industry. And as for plastics – they were anathema to the tradie, who knew that plastic should only be used for toys, radio cases and decorative products, which were preferable in Bakelite, anyway. Brushless motors were not even considered important.
It was the introduction of cordless tools that eventually led to the need for brushless motors. Brushless motors had been used widely by industry to drive conveyor belts in manufacturing facilities since the early 1960s, with little if any interest by power tool companies. It was Makita that first used them – not for the building industry, but rather in their assembly of aerospace and defence equipment in 2003. It took six more years for them to reach power tools for sale to the trade; in 2009, Makita released a three-speed impact driver. However, the incredible increase in sales of cordless tools from their inauspicious beginnings – as a DIY tool with ni-cad batteries and a reputation for ‘dying’ at regular intervals – to state-of-the-art, lithium-ion driven wonder tools took everyone by surprise.
Such was the demand for better, faster and more streamlined tools that companies examined the means that would provide all of these, plus the added benefit of longer-lasting, reliable models. Brushless motors constituted the introduction of an old technology, made especially effective by contemporary innovation. Miniaturisation of electronic technology meant vast improvements in brushless motors.
Rightly described as ‘smart’, these electronics communicate directly with the motor and the tool responds according to the job being undertaken. For example, if a tradie is drilling into hardwood, the electronics sense this and the tool pulls more charge from the battery. The reverse is true if screwing into foam insulation boards.
Simply put, the brushed motor has a ring of stationary magnets and spring-loaded carbon brushes on the central motor shaft, around which spins the armature and commutator.
The spring load pushes the brushes against the commutator.
Problem: brushes wear, heat builds up. In the brushless motor everything is reversed and the commutator and brushes are gone. These are replaced by a small circuit board that coordinates the energy delivery to the windings. The copper windings are now on the outside of the motor configuration and, as such, can be increased in size – which equates to greater power. Another benefit is the wear and heat build-up caused by the dragging of the brushes against the commutator is gone and there is no voltage drop causing reduced efficiency.
These tools cool faster and are very reliable. The removal of the commutator and brushes allows for smaller and more streamlined casings and as a result the power tools of today far exceed the power of the heavy cumbersome corded tools of yesteryear.
Although more expensive to produce, the demand for brushless motor tools will force the industry to use brushless motors on more tool ranges.