DeWalt’s assembly plant is located in Charlotte, North Carolina in a building that for many years housed a Black & Decker distribution center. It is now owned by Stanley Black & Decker and houses both a factory and warehouse space. The building spans the border to South Carolina; if you walk far enough in you will cross the state line.
The factory occupies 65,000 square feet and is surrounded by 1.2 million square feet of warehouse space. The areas are separated by floor-to-ceiling storage racks, which had banners hung over them for the media event. This was probably done to provide a better looking backdrop for the media event and to obscure the gazillions of pallets of SB&D products stored in the distribution area.
Tools are assembled in “cells” where teams of workers are trained to do every job—and switch every few hours. There are currently 16 cells in the plant and they can quickly be switched to the assembly of different products. The workers in this cell are currently assembling 20V MAX hammer drill drivers.
Components are staged along the back side of the cell on sloped rollers so as one box of parts is depleted another rolls forward to take its place.
This worker is soldering the wires from a switch assembly to the contacts on a brushless motor. The switches came out of a box labeled Thailand and the motors out of a box labeled China. Other parts were produced in the U.S. by SB&D: plastic housings in Cheraw, SC, gear housings in Hampstead, MD, and machined parts in New Britain, CT. The rest of the parts come from other places. And of course, sourcing varies by product and can change over time; DeWalt plans to begin building brushless motors in Charlotte later this year.
The switch, motor, and gear/chuck assembly have been placed in a “clamshell” housing that is resting in an assembly jig. The next step is to place the other half of the housing over this one and screw it in place
The gal in the foreground uses a pneumatic screwdriver to join the two halves of an impact driver’s case. A similar process is used on the drills and recip saws assembled at the plant.
Lithium-ion tools contain electronics that control charging, discharging, and other thing related to the performance of motor and battery. Before the tool can be used the EPROM (erasable programmable read only memory) chip must be programed with the “instructions” for that particular tool. This station is set up to program the chip in a particular model of impact driver with instructions such as the temperature at which the tool automatically shuts off to protect the motor and battery. The EPROM is similar to the BIOS or ROM chip on the motherboard of a computer—it retains its programing when the power is turned off.
This impact driver is in the machine that programs the memory chip. It is held in position by sliding it on to fitting similar to that on the top of a 20V MAX battery.
The next step is to test the performance of the tool by placing the tool in a machine and connecting its chuck to a device resembling a dynamometer. The motor must turn the device, which is set to provide varying degrees of resistance.
The testing machine compares the performance of the tool to a list of design parameters. If the tool passes the bars along the right side of the computer screen above turn green. This hammer drill driver passed and is ready to be labeled and packaged. If an individual tool fails they will set it aside for reworking (repair). If a bunch of tools fail they will stop production while they figure out what is causing the problem.
The testing machines leave a mark on the base to indicate the tool has been tested. The marks on this tool show that it has been through two different tests. If a mark is missing you know someone skipped a step.
Having passed its performance test this hammer drill driver is having labels applied. At first I was amazed by how many labels go onto each tool. But then I remembered doing a teardown of a DeWalt impact driver and how many labels I had to slit to get the case to come apart. Interestingly, DeWalt uses a jig equipped with laser beams to check the labels on each tool and make sure all of them are in place.
A whole bunch of labels are being applied to an 18-volt XRP recip saw. When the plant first opened it only manufactured XRP tools (which take the old post-style batteries). Now it produces XRP and 20V MAX.
These 20V MAX impact and drill drivers are being packaged together in combo kits. The production cells for these tools are set up end-to-end. Tools advance left-to-right on one and right-to-left on the other so they end up at the same place when they’re finished.
This tool kit is resting on an electronic scale. Why do they weight it? The weight will be off if something is missing—like the belt clip or manual. If the weight checks out they shut the case and enclose it in one of those cardboard wrappers that cover the center of the case but not the ends.
These are the models that are assembled in the Charlotte, NC plant—20V MAX on the left and XRP on the right. Not every tool will be made at the same time. In any given week production cells might be set up to assemble a particular model or particular group of models—depending on what selling well and what’s in stock.
Some of the brushed motors used at the assembly plant are assembled and wound at the factory. The machines you see here (there are two of them) are used to make armatures by wrapping copper wire around the metal plates in the armature stack. It happens so fast you can barely see it. The spools on the pallet contain wire. They are unwrapped, placed under the upside-down trash cans and fed from there into the winding machines. I do not know where the stators are made.
I have no idea what the folks on this part of the motor line are doing. They’re pulling armatures off, looking at them, and then putting a stripe on them with some kind of marker. Whatever they’re doing, it looks kind of cool.
Rotors spin at very high speed so they need to be dynamically balanced—which is what this machine is doing. It spins the rotor, determines where it is heavy, and then grinds a small amount of metal away from the plates on the rotor. If you’ve taken apart a tool motor and seen dished out areas on the sides of the rotor, that’s from balancing. The process is akin to dynamically balancing a tire, but instead of adding weight you subtract it.
Finished motors are boxed and set aside until needed. Why box them? Because they’d be damaged if you simply threw them into a bin.