A New Motor Makes For A Stronger 18-volt Drill

Now this is awesome...I LOVE seeing things get more power and ALSO becoming more efficient...now that is science and engineering at its best people

And in our "How to build a better knee-capping tool department ..."

Glad to see Milwaukee really stepping up again in innovation. Keep it up. What will be next - graphene power sources??

I like popsci, but this article is quite poor in the science content department. The drill maker has switched from brushed DC to brushless DC motors. These are by no means "new". They've been used in computer fans, CD and DVD drives, floppy drives and hard disks for I think two decades. And high-powered versions (capable of powering a drill or something bigger) have been used in radio controlled models for a couple of years by now.

Secondly, any engineer will tell you that it's not torque that gets work done, but power, because power = torque x RPM. So torque tells you how big a drill bit it can spin, or how hard you can press the drill into whatever you're drilling without it stalling; POWER tells you how much RPM the drill can spin the drillbit at under those conditions. The fastest drill when it comes to making holes will be the one that has the most power (refer to the equation above) because it can supply the torque you need at the fastest RPM - or conversely, it can supply the RPM you need at the greatest torque.

And the huge advantages of brushless motors are mainly due to these two factors (NOT because you can use bigger magnets, although it helps) - 1. No brushes means much less friction and 2. There's a limit for the current density (amps per square inch) a brush can handle and still give a long service life. Handling more current would need bigger brushes - that would cause more friction. So removing the brushes will remove this limitation and allow more current to be dumped into the same sized motor.

Also, in a brushless motor, it's the magnets that spin, not the wire coil (aka armature) like in a normal motor. The magnets can either be outside the coil of wire (outrunner) or inside (inrunner). The article doesn't say which kind was used, but if they opted for an outrunner, then the greater torque is coming from the fact the thing driving the shaft (i.e. the magnets) have a larger radius, thus a greater moment arm and thus more torque.

@LMF5000

Really bro get off your high horse...What have you improved upon or invented that actually did something...ALSO hate to tell you but POWER is not an actual rating bro...get a grip my man...POWER is a general term for things like HORSE POWER and TORQUE maybe you should google harder.

I have the previous model, and the 18v impact driver that I got in a two pack that came with two batteries included and a 3rd free battery for $200. I love these things, way worth the little bit of extra money if you find them on sale. Of all my tools, I never thought a hand drill would be my favorite, but they're made really well, theres metal everywhere there should be metal, I never run out of juice if the batteries only take 20-25 minutes to charge and last a good amount of time, and my favorite nitpicky thing is the lithium ion dies instantly, it doesn't think about going dead for 30 minutes before you're done using it. It may just be a psychological thing, but it seems decisive and honorable.

@LMF5000

I'm completely with you. You hit the nail on the head. Brushless motors aren't really anything new. It may be that their application to cordless drills is new, but this really isn't very cutting edge stuff. This article feels more like a paid advertisement.

I agree with Delkomatic but also with what he said, LMF5000 it not that it's "new" necessarily, but that they have found a new use for that technology. A new application for an invention is as much of an achievement in creating "new" sciences and things as making a completely new invention in of its self.

I agree with LMF5000. Is it a stepper motor or a three phase brushless motor?

Yes it does matter Delkomatic, the purpose of this magazine WAS to explain how it works, NOT just write to the lowest level ... bro. If I wanted this level of fluff, I would read the ads.

I have a perfectly good "battery drill" but every time I need a new battery it is cheaper to buy a new drill and throw it away because all tool batteries are incompatible with each other and the new drill comes with two batteries making it cheaper than buying one replacement battery!!!
electricity is a "commodity" but the tool companies are "playing games" by making THEIR batteries incompatible with their competitors. It is like buying an every ready flash light and not being able to put ray o vac batteries in it!!!!
Richard Lauring Cushing WI

The motor control is PWM, Pulse Width Modulation. But it's more than that. It's an integrated motor, battery and an additional electronic control of the PWM so that the battery and motor are both optimized, but protected. None of these on their own is revolutionary, but to my knowledge, Milwaukee is the only company putting all this tech together in cordless tools.

Milwaukee has a video on its website showing their M18 drill winching a payloader, and then another brushless / lithium drill doing the same and burning out. It's possible for a motor to overload (use too much current) which can overheat both the battery and the motor. The thing about lithium batteries is that they can provide higher amperage than most other battery types, which can be too much of a good thing in some situations.

Milwaukee is providing the type of integrated motor/battery management that is found on things like hybrid cars or VERY high end laptops. You know that hot laptop battery phenomenon? That's an unregulated PWM system.

Power is many things.
Amps x Volts.
RPM x Torque.