Brushless Motors

DeWalt 20V brushless motor impact tool www.dewalt.com
DeWalt 20V brushless motor impact tool www.dewalt.com
Published On
Apr 15, 2020

The impact of brushless DC motors for battery-powered hand tools is often compared to the lithium-ion battery revolution. Together, these two technologies have changed cordless tools used by electricians and those in other trades.

Brushless design eliminates brushes and commutators while a circuit board coordinates the electronic energy within the motor.

The result is a brushless-motor-powered tool that is more efficient and durable than one powered by a conventional electric motor.

Tools with brushless motors are often described as smart because an electronic signal communicates directly with the windings and adjusts power draw to the task at hand, rather than always operating at full speed. When the motor senses a lack of resistance, it draws less power, which extends battery use per charge.

As more tools with brushless motors became available, manufacturers began to promote the benefits of their brand’s motors, just as they do with their brand’s lithium-ion batteries.

While relatively new to the professional hand tool market, brushless motors have been in use for years.

“The advent of the brushless motor can be traced back to the 1960s, when they were primarily used in industrial and manufacturing applications,” said Michael Gorman, director of product marketing at DeWalt, Baltimore. “In terms of the power tools, brushless motors were first were used in 2003.”

However, brushless motor tools weren’t introduced to the market until 2009.

“There are many different types of motors that technically qualify as brushless, induction motors being an example,” Gorman said. “Within power tools, brushless motors consist of a permanent magnet rotor, wound stator and electronic sensors. The designs have been refined to make them smaller and more powerful, allowing them to expand to offer solutions to new applications over time.

“One of DeWalt’s first cordless, brushless products was an impact driver. As power increases and control methods advance, we use brushless technology in products that reach output powers equivalent to traditional AC products.”

Gorman said brushless motors are smaller and lighter than brushed motors, which addresses the ongoing user demand for ergonomic improvement and increased performance.

Also, permanent magnet technology in brushless motors is a more efficient solution than brushed motors, and users see a significant reduction in maintenance (no brush changes) and extended motor life.

It also is important that brushless motors adjust to the task as electronics determine the power necessary to complete the application.

“Speaking as a representative of DeWalt, we have a motor platform strategy that is purposeful in our pursuit to deliver applications needed by tool users. The motors play a supporting role to the overall design solution,” Gorman said. “In general, all manufacturers realize similar advantages from the brushless motor technology: increased performance, lighter weight and improved durability.”

Gorman said the last five years have seen an accelerated adoption cycle for brushless products, specifically within the professional power tool arena. DeWalt estimates that brushless tool products represent more than 30% of the professional market.

“While expectations and projections are to see brushless tools extend and expand the professional power tool market, the significant price premium versus brushed motor tools—approximately 30%—will keep some consumers and do-it-yourself markets aligned to the traditional brushed platforms,” he said.

DeWalt’s brushless products range across all major platforms and include fastening tools, cordless impact wrenches and drivers, cordless nailers, cordless rotary and hammer drills, circular and linear-edge cutting tools and cordless material-removal tools.

Robert Chetelat, senior product manager at Hilti, Plano, Texas, said more than 50% of Hilti tools sold today have brushless motors.

Hilti cordless metal nibbler with brushless motor www.hilti.com
Hilti cordless metal nibbler with brushless motor www.hilti.com

Hilti began selling brushless motors in cordless tools in 2012 and has steadily increased the number of products using brushless motors because they meet customers’ lifetime and performance expectations, Chetelat said.

He said because a brushless motor commutation is controlled electronically, not mechanically, the motor provides a wear-free design, increased efficiency, a much more durable motor, and a performance difference in run-time, power and application speed.

“Brushless motors allow us to improve the size of a tool, its efficiency, noise level and performance,” Chetelat said. “Often brushless motors are shorter than conventional brushed motors, and that helps reduce tool length. When we move to a brushless motor, we can increase the efficiency of the motor, which increases the amount of work per charge that a cordless tool can perform.

“Combining a higher efficiency motor in the design of our drive (motor and gears) results in less noise generated. Less noise means more of the energy from the battery is moving through the tool and into the application,” he said. “Finally, a tool can take on more demanding applications and complete the applications before the tool overloads.”

Chetelat said Hilti continues to improve motors to achieve more applications per charge.

“We have been able to increase the number of peak amps the motor can withstand when applications get demanding,” he said. “As we continue to get more efficiency out of our tools, we often can reduce the noise the tool produces. Less weight and less noise may improve the health and safety of the user. This means tools like our 36V SDS Max cordless tool can perform at the same level or even perform better than corded versions.”

Chetelat added that the choice of brush or brushless motors still depends on which motor can deliver the best performance and reliability for work to be done. There may be a day in the future when all tools use a brushless motor, he believes, but there may always be a few exceptions where the brushed motor is the best solution.

While there are common features to brushless motors, such as no commutator and electronic motor control, Chetelat said Hilti develops motors to meet customer’s specific expectations and for reliability.

“We go directly to professional users of tools to learn their expectations for performance and reliability,” he said. “Professionals use tools every day to make their living, and they depend on the tools at a much higher level than a hobbyist using a cordless tool a few weekends a year.”

Hilti tools with brushless motors include impact drivers, impact wrenches, hammer drill/drivers, rotary hammer drills, combi-hammer drills, circular saws, jig saws, double cuts, cutout tools grinders, band file, tube belt sander, burnisher, nibbler and drywall screw gun.

Emily Oursler, product manager at Metabo HPT, Braselton, Ga., said brushless motors solve many limitations of their brushed counterparts by providing benefits that include smaller size and weight, reduced heat and noise, improved efficiency and reduced maintenance.

Oursler said brushless versions of power tools also have a lower susceptibility to mechanical wear than brushed counterparts, and the battery used with a cordless, brushless motor drill will last longer per charge than with a brushed drill. And advancement in the use of an electronic circuit can detect the load on the motor and adjust the current accordingly.

“Power tool brands have a tendency to incorporate premium features into brushless tools such as electronic settings to adjust torque and speed to change power that will suit the application for the user,” she said.

While noting brushless motors are making a growing impact, Oursler believes it will be a while before the technology impacts all power tools.

Metabo products with brushless motors include SDS plus hammers, driver drills, band saws, circular saws, finish nailers, framing nailers, grinders, miter saws and screwdrivers.

Metabo HTP multivolt cordless brushless driver kit www.metabo.com
Metabo HPT multivolt cordless brushless driver kit www.metabo.com

Paul Fry, senior vice president of product management at Milwaukee Tool, Brookfield, Wis., said brushless motor has transformed into a catch term. With a design inverse to a traditional electric motor, the copper windings are on the field/stator of the brushless motor and the magnets on the armature. Efficiency is increased because the tool draws less current to do the same amount of work, and it doesn’t decrease efficiency like the mechanical commutation. By eliminating mechanical parts within the motor, electrical commutation optimizes tools for increased reliability and overall usage.

“Even so, every brushless motor is not created equal,” he said.

Like lithium-ion batteries for tools where not all cells are made the same, not all brushless motors accomplish the same goal.

“Since their introduction to the power tool market, brushless motors continue to improve. To enhance brushless motor performance, Milwaukee Tool focuses on incorporating state-of-the-art magnets, winding design and more when building motors. When incorporating brushless technology into our motors, we customize motor electronics to each tool, rather than taking a one-size-fits-all approach. The ability to tailor robust motor technology to the specific needs of the tool is key to performance as well as efficiency,” Fry said.

Milwaukee M18 brushless threaded rod cutter www.milwaukeetool.com
Milwaukee M18 brushless threaded rod cutter www.milwaukeetool.com

However, he said, best-in-class performance and run time can’t be achieved simply by putting a brushless motor into a tool.

“By tying brushless motors to the most capable electronic packages and most advanced lithium-ion batteries, the boundaries of cordless tool performance are enhanced to truly experience the productivity benefits that a brushless motor has to offer,” he said. “This complex interworking of lithium-ion, motor technologies and electronics is what has made our 12V and Fuel products truly different from other brushless tools on the market.”

Fry said currently more than half the tools in those product lines are brushless, and there are opportunities to expand brushless motors to tools that would benefit from the increased performance.

Milwaukee Tool’s brushless motor-powered tools and equipment include drills and hammer drills, rotary hammers, crimpers, band saws, reciprocating saws, circular saws, table saws, threaded rod cutters, pulling fish tapes, impact drivers and wrenches, pipe threaders, nailers, grinders, press tools, blowers, string trimmers, chainsaws and some types of light equipment.

About the Author

Jeff Griffin

Freelance Writer

Jeff Griffin, a construction and tools writer from Oklahoma City, can be reached at up-front@cox.net.

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