Big improvements in battery life and run-time pave the way for more widespread adoption
May 1, 2012
Odds are people laughed at the idea of a cordless hand tool ever replacing a corded tool on an assembly line, but the sight of a bank of charging stations at a major manufacturing plant is increasingly common. With that in mind, could more cordless tools be found on the fabricating shop floor in the future?
For the do-it-yourself homeowner, the tool of choice is the cordless drill. It’s portable and gets the job done.
Metal fabricators are similar to DIY guys. They usually don’t need assistance to complete a task, and they like their tools. Doesn’t that suggest they might like a cordless choice in power tools as well (see Figure 1)?
The large OEMs know the answer to that. On those long assembly lines where cords from screw guns used to clutter the floor or where air hoses connected to pneumatic tools hung from the ceiling, a visitor now can see workers going about their jobs without being tethered to anything. They are relying on cordless tools and scheduling that allow them to go back and forth to an area where charging stations await with fully charged batteries ready to assist in keeping the assembly moving. It’s a cleaner line without the safety hazards associated with cords that could be a trip hazard or the added expense of keeping an air compressor running for pneumatic tools. It’s a new way to approach assembly.
“Obviously, we see this trend in fastening tools—drill drivers, impact wrenches, and hammer drills—which really don’t have much of a place in the metalworking industry unless you are a fabricator that does installations, such as hand railings and things of that nature,” said Ernie Leopold, product manager, Fein Power Tools Inc.
“But we are also seeing it in grinders and magnetic-based drills—just about anywhere you can take a power tool, you can cut the cord,” he added. “We are starting to see a trend there.”
Of course, metal fabricating today is plenty different from what it was 20 years ago, and many fab operations may be in a position to be more open to cordless technology. Value-added services such as fieldwork or the nature of the application, such as constructing a ship hull on which portability improvements would be welcome, might cause fabricators to consider cordless tools. Whatever the case, fabricators are open to the idea of cordless tools, but are the tools ready for the world of metal fabricating?
They are getting there, according to Paul Fry, Milwaukee Electric Tool’s vice president, cordless product management. All you have to do is look at pneumatic impact wrenches, which dominated manufacturing environments for many years, and you’ll see more cordless high-torque impact wrenches that can match the air-powered tools in performance, he said. For instance, Milwaukee Electric sells a 0.5-in., 18-V, high-torque impact wrench that delivers 450 ft.-lbs. of torque—not exactly what you would expect to see if you haven’t looked at cordless power tools in 10 years or so.
“We see them in a lot more production floors, maintenance shops, automotive shops, and places like that because they have the power to do the job,” Fry said.
Arguably, the cordless power tool market entered a new era with the introduction of lithium-ion batteries in the mid-2000s. Until that time nickel-cadmium had dominated the portable tool market.
Actually, lithium battery technology dates back to the early 1900s. Even though lithium provides the largest density for weight when compared to other readily available metals, early work with lithium batteries led to dead ends because lithium is inherently unstable, especially during charging. Research shifted to the use of lithium ions instead of the metal, and developers found a stable chemistry on which to build its products. Widespread commercialization occurred in the late 20th century.
It wasn’t long afterward that the lithium-ion technology worked its way into other industries, not just portable electronics and mobile computing. The energy density of lithium-ion is typically more than nickel-cadmium’s, and a lithium-ion battery doesn’t have as much of a dramatic power drop-off toward the end of the discharge cycle like a nickel-cadmium battery does. The market was waiting for such an innovation.
“The newest and latest tools have a 20- to 30-minute charge time, which is much improved over the recent history of one to two hours’ charge time,” said Mike Marshall, who is involved with technical sales and marketing for industrial power toolmaker CS Unitec.
Lithium-ion battery technology is destined to improve in the coming years. Fry said his company’s top-of-the-line batteries today, for example, deliver 40 percent longer run-time and 20 percent more power than lithium-ion batteries sold four years ago.
Another area of improvement in cordless power tools is brushless DC motors. These motors are more efficient in converting electricity into mechanical power because they simply don’t have the electrical and friction losses the brushes cause. A typical brushless DC motor has a fixed armature and permanent magnets that rotate around it, and an electronic controller takes the place of the brushes—carbon pieces that pass current to the rotor-mounted windings in a brushed DC motor design—to power the motor. This design has translated into motors with more torque per weight, increased reliability, and longer lifespan because there are no brushes to erode over time.
Electronics are the other noteworthy advancement in cordless power tool design. They protect power tools from overload and thermal burn-up, two significant shortcomings of older cordless tools. They also have led to the creation of fuel gauges for batteries, so that power tool users no longer are flying blind when they pick up a tool and wonder just how much power is left in the battery.
“Not only are cordless tools becoming more powerful, they are becoming lighter-weight, more compact, dependable, and have a longer run-time. There have been tremendous advances in cordless in just a short amount of time,” Fein Power Tools’ Leopold said.
As with any equipment discussion, the proof is in the application. Just how will it work in the real world, not in some product reliability lab?
Metabo introduced its first cordless magnetic-core drill at the 2011 FABTECH® in Chicago. The tool’s 25.2-V lithium-ion battery is powerful enough to provide cutting power for 12 to 15 holes in structural steel beam. Another battery is kept on the magnetic drill and can be switched out quickly, so the fabricator can continue drilling. The battery requires about 15 minutes in the charger to receive a full charge. The tool can drill a maximum diameter of 1.25 in. with annular cutters and a maximum depth of 2 in.
As an example of a good application for the power tool, Terry Tuerk, Metabo’s product manager, pointed to the ceiling of McCormick Place, the convention center where FABTECH was being held, and said, “If someone is told he has to go up there and drill some holes in those beams to run some electrical cord, do you think he wants to hook up 200 feet of cord to power the drill?”
The cordless trend has even moved into the surface finishing arena with more cordless grinders being available for fabricators. Milwaukee Electric Tool offers 18- and 28-V models that are much more powerful than previous generations of nickel-cadmium cordless tools (see Figure 2). Fry described the tools as being strong enough for the operator to “lean on the tool” as he uses it to grind the metal surface.
Yet even Fry admitted that there is work still to be done in the metal surface preparation area when it comes to cordless tools.
“The user will quickly correct you and tell you it’s a cutoff tool and not a grinder yet. That’s one of our challenges,” he said. “Today it’s primarily a great cutting tool for a lot of folks.”
Leopold added that cordless power tools might be a good addition to a toolbox, but for the most part, metal fabricators are willing to stick with the corded tools.
“As far as continual-duty use—maybe someday down the road I’ll eat my words as technology advances—but right now in the marketplace, I don’t see a cordless tool replacing a corded tool in most circumstances in metalworking,” he said.
Of course, circumstances are always changing. More and more, customers are asking fabricators to take on responsibilities that go beyond the realm of just bending, cutting, and joining metal. Perhaps some of these new challenges will call for a cordless product. Whatever the case may be, the power tool developers are going to keep working to improve the performance of cordless power tools.
“The technology is coming,” Fry said, “whether it’s the advancements we have seen in [lithium-ion battery packs] or motors. We are going to close the gap to some extent, and I think we are going to pull more and more things into the realm of possibility.”