I recently had the opportunity to tour Milwaukee Tool’s Greenwood, Mississippi manufacturing facility, where they produce Sawzall blades and hole saws.
Milwaukee Tool invited ToolGuyd and several other tool industry media to visit their Mississippi facility. For the sake of transparency, I’d like to remind you that media event hosts often cover airfare, hotel accommodations, food, and in some cases entertainment. This trip was no different.
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Although some might not find it very exciting to learn about how cutting accessories are manufactured, there are still several interesting processes going on here.
Introduction
The Greenwood plant has been open since 2001 and has undergone expansion in the past few years. Their total space now sits at 390,000 square feet and they employ 670 people. To put the number of Sawzall blades they’ve made since 1999 in perspective, they gave the example that they could fill the square footage of the Empire State building 9 times with blades.
While we were able to see most of the current manufacturing floor, photos and video coverage could only be taken or recorded at predesignated areas. Even though it sounds stringent, they allowed us to take photos of other things, but they wanted us to ask for permission first.
We were told the biggest concern was that they didn’t want the competition to see their manufacturing capacity, so they wanted to prevent wide angle shots of the factory floor. When I pushed them on this further, saying that you can see how big their buildings are in an aerial photo, they said that it isn’t just about the amount of manufacturing area you have, it’s how efficiently you use the space.
Stuart’s Note: I’d think there’s more to it. If I operated a factory, in addition to keeping capabilities and capacities private, I would seek to protect the “how” and “why” my products were manufactured a certain way. Still, some factories prohibit photos or videos at all, so we’re grateful we’re able to share a glimpse of what Ben saw and experienced on the tour.
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There were also areas that were off limits; most of the second building was completely cordoned off. They hinted that they were working on manufacturing some new products at the plant.
In order to keep this post a readable length, it will focus on how Milwaukee the manufactures regular Sawzall blades. I’ll save the story about how Milwaukee manufactures Hole Dozer hole saws for later.
See Also: How a Sawzall Blade with Carbide Teeth is Made
How Sawzall Blades are Made
In general the process for making a Sawzall reciprocating saw blade is as follows:
- Uncoil a long roll of raw material
- Stamp out a blade
- Grind the teeth
- Set the teeth
- Heat treat the blade
- Powder coat the blade
- Print the graphics
- Package the blades
We didn’t follow one specific blade type through the process or just look at one line. They showed us several different lines making different blades so all the photos and videos of different stages are not necessarily the same style of blade.
Uncoiling the Roll
We started with the production of some bi-metallic blades. The blades start as a coil of flat stock that is unspooled into a machine that stamps the blades from the stock.
If you have heard the term bi-metal or bi-metallic thrown around before, but aren’t exactly sure what that means, don’t worry – I wasn’t sure either.
In the case of a Sawzall blade, it means that a thick strip of spring steel is welded to a thin strip of hardened high-speed steel. The spring steel gives the blade flexibility, while the hardened steel keeps the teeth sharp.
Stamping the Blades
Each blade is stamped out with very little waste, and what waste there is gets recycled.
Grinding the Teeth
We weren’t able to take photos or video of the grinding process, but Milwaukee really wanted us to take away that the teeth are not milled before the blades are stamped.
With milling, you have a cutting tool that degrades as it’s used, and so each tooth that is cut is a little worse than the last until it’s no longer in spec. Milwaukee redresses their grinding wheel with a diamond wheel after each 3 inch stack of blades has run, so the last tooth cut is identical to the first.
We were then shown some competing brands’ reciprocating saw blades. Looking at these stacks of blades, it is obvious that the teeth don’t line up. This results from the teeth being milled before the blades are stamped out.
Milwaukee claims that this leads to differences in cutting performance from blade to blade and that the process they use instead, where the teeth are ground after the blade has been stamped, results in blades with identical tooth patterns and identical cutting performance
Setting the Teeth
They then wash the blade and then set the teeth. Here is the tooling they use to set the teeth on a blade.
In this video, the robot (of course painted painted Milwaukee red) is taking 3″ stacks of blades that have just been washed, and distributing them among the four teeth setting machines on this line.
Once in a setting machine, a single blade is taken out of the stack, moved to the setting jaws for the teeth to be set, and then finally placed into a new stack.
Setting the teeth of a blade angles the teeth of a blade in an alternating pattern, so that the kerf of the cut is wider than the blade. This is so the blade doesn’t bind and so that the blade can pull material out of the cut.
If there is too much set, the kerf will be too wide and it can damage the blade. If there is too little set, the blade will perform badly. Generally to cut harder materials, you use a smaller set than softer materials.
Heat Treating
After the teeth have been set, the blades are heat treated. We weren’t allowed to record in this area at all, so I’ll have to explain what goes on here.
Rather than heat treat the blades in large batches, where the temperature from one part of the batch to another can differ as much as 50°F, they do heat treating in small batches, in small electric-fired ovens — three trays of blades in a single layer — so they can minimize the temperature differential to 0.5°C. Then they cool the blades with nitrogen that is generated on site.
This small batch size also allows them to be more versatile, and to quickly changing the process to meet demand. For example, they had stack of step bits from their sister plant in Jackson, Mississippi waiting to be heat treated.
Stuart’s Note: Heat treatment has HUGE effects on the final product. If a blade is hardened too much, its teeth will be brittle and prone to breakage. If it’s not hardened enough, the teeth will wear quickly.
Read More: Milwaukee USA-Made Step Bits
Powder Coating
We were shown two different powder coating lines. The first line — the hang line or quick change over line — had workers placing blades on the above racks which made a circuit into the coating room behind them. There was then another group of workers removing the coated blades from the racks after they had been through the oven on the other side of the powder coating room.
The second line — the belt line or automated line — had one person loading stacks of blades into a machine that evenly distributed them on a conveyor belt. That belt then traveled into a different powder coating room
Watching the video you can see that the automatically placed blades aren’t always in perfect position. We saw the guy loading the blades run in a few times to put missing blades in the row.
One thing they didn’t let us photograph or videotape was the blade flipper-over. I’m sure it’s a pretty standard way to flip products over on a line, but it was still neat to watch.
After the first coat and oven baking, an arm picked up a row of blades with a magnet and dropped them onto another magnetic belt that was perpendicular to the line. Then the belt turned until all the blades were positioned upside down above the line, and then dropped them back onto the line with the uncoated side facing up. The blades then went through a second powder coating hood like the one above, and then another oven and cooling tunnel.
Printing Graphics
Above is a video of the high-speed printer Milwaukee uses to print the text and graphics on their Sawzall blades.
It’s really fast and highly automated. It’s a U-shaped assembly, but for some reason we weren’t supposed to photograph the first part.
A robot magnetically picks up two blades from a line of blades. It puts them on the conveyor which then runs under the high speed printer and a UV curing light. At the end, another robot stacks the blades and a human loads up for them next step.
Before the event, Milwaukee requested a ToolGuyd logo for a special surprise. It turns out they wanted to demonstrate the capabilities of their high-speed printing line.
I can be really dense sometimes, because I took a photograph of this table thinking it was just an example of the different blades they could make. Only later when some of the other media people were showing me pictures of their logo printed on a Sawzall blade did I realize just what I had photographed.
Packaging the Finished Blades
The final part of the process is packaging. Here they weigh every set just to make sure there is the right number of blades in the package. This line is also automated, but there are people loading the blades and watching the process. I saw a person fix a packaging problem right on the line.
In the video, you can see a person on the right dropping a stack of blades into the front half of the plastic packaging. The robot then pulls the cardboard insert down from a stack above it, places it on top of the blades, and makes sure it folds right. Then as the packages move down the line another robot pulls the plastic back out of a stack above it and puts it onto the package.
What About the Carbide-Toothed AX Blade?
You’re probably thinking, this is all well and good, but what about the AX blade with carbide teeth? Well, the process behind making that blade is different from a normal bi-metal blade, so I’m going to save it for the next post.
See Also
If you missed it, check out our other factory tour coverage of how Dewalt brushless drills are built in the USA.
Part 2: How a Milwaukee Sawzall AX carbide-toothed blade is made!
KL
Thanks guys. Interesting
Man_With_Plan
Awesome, makes me want to buy the AX sawzall blade!
Adam
Oh the irony. I was just looking at a Milwaukee hole saw kit the other day and was thinking about how it was made. I knew it was made in the USA, so thought it was more feasible to find out. Low & behold, thank you Ben for a timely answer to my inner mind ponderings!! The saw-zal blade production was enough to hold me over for the next factory review. Thanks
Pete
The hole saws are fantastic. Ive cut a lot of stuff with them including some fairly thick metal(using cutting fluid) and theyre still great! Not to mention theyre warranty which if i rember right if a tooth is broken they’ll warranty it. I have a milwaukee service center 1/2 mile from my shop but havent had to use it yet…
Jim Felt
I’ve a question. How important is the touted “consistent alignment of the teeth” to the long term functionality of these blades?
In the side by side photo there is an amazing lack of tooth consistency amongst the (presumed) other brands. But what exactly does it mean in terms of actual use?
Great story and videos too!
Benjamen
If you are looking at blades that don’t have something like the fang tip, having a the teeth spaced differently at the very tip is going to affect plunging from blade to blade. As their guy put it “sometimes you get a tooth and somethings you don’t.
In the meat of the blade maybe from blade to blade you can get a difference of 1/2 of a tooth on a stroke. Maybe, it adds up?
I think it does show how precise their manufacturing process is and it might be a perception issue. Are you going to trust a company with a nice tight stack of blades that all line up perfectly in the package over a stack from a competitor that doesn’t? I don’t know, but packaging in the stores is a big part of why people buy things.
Even though in the tour they said all of the blades of a type are set the same, I have noticed that some Milwaukeee blades are set the opposite way (mirrored) of others in a pack. I asked Milwaukee if this made a difference and they basically said no.
Jimmie
Does milling teeth after stamping offer any other advantages? What about disadvantages? Presumably the other brands decided that milling teeth before stamping offered other advantages? Or is it a six-of-one-half-dozen-of-the-other type thing other than blade-to-blade uniformity?
Tony
In Six Sigma parlance, it helps eliminate variability from the process which in turn makes for an easier assessment of quality control.
Benjamen
Evidently some companies used to cut their blades out of band saw stock. I guess if you already have the rolls of toothed stock on hand it’s a quick way to get into another product.
On the tour Milwaukee was quite adamant that they ground not milled the teeth. Again they said milling cutters wear over time — that the first tooth cut isn’t going to be the same as the last tooth cut, but I think there would be process control methods to compensate for cutter wear.
With grinding they redress the grinding wheel periodically to make sure it’s true, but obviously you are going to wear down the grinding wheel too. So they still must have to compensate for that just like you would have to for milling.
A disadvantage of grinding the blades after they are cut might be that it’s probably harder to handle individual blades of various sizes than a continuous strip of metal. The longer you can keep the continuous band of metal the less tooling you probably change out when you change blades sizes.
David Frane
Hi Ben,
Lenox has always cut teeth first and then stamped out the blades. Makes sense that they would given that bandsaw blades are the company’s number 1 product. As someone else here said, the only problem I could see with that is if it made for a misaligned “fang” tip. Can’t name every company that makes recip blades in the U.S. but the biggies are Milwaukee, Lenox (MA), and Morse (Ohio). DeWalt makes at least some of their blades in Kentucky. Lenox OEM’s blades for Irwin (both now owned by SB&D) and a number of other companies. If a linear blade (recip, jigsaw, etc) is labeled made in Switzerland odds are it came out of a plant owned by Bosch. Considering how many tools are made overseas it’s interesting to see how many companies kept production here.
A W
This is awesome. Thanks guys!!
fred
Interesting.
The funny thing is that I used to get some feedback from the crews about other disposable items like screwdriver bits, circular saw blades and jigsaw blades – particularly if the guys found something they liked or hated. I don’t think we got a lot of feedback on recip-saw blades – often picking up what was needed for a job locally – and buying what was available or struck the eye from among brands like Bosch, Diablo (Freud), Dewalt, Lenox, Milwaukee, Morse and Starrett. When we’d do an inventory – this agnostic approach could be seen in the mixed bag of recip-saw blades we had on hand. I’m guessing that there are differences between brands but we were never scientific enough to have discerned them.
fred
Looking at an old inventory confirms to me what I said – We had many more Wera Screwdriver bits on hand, mostly Freud portable circular saw blades, and mostly Bosch jigsaw blades – but lots of different recip-saw blades.
firefly
This is just too cool. Thanks Ben for sharing!
Chris
I would like to see how dewalt manufacturers their pilot point drill bits.
John S
Maybe a dumb question, but why do they bother powder coating / printing the graphics on the blades. After the first use, most of that is gone and it doesn’t seem to really add anything other than aesthetics as its heat treated before hand and I don’t imagine rusts just sitting there. I wonder how much they’d save nixing those two steps alone. Even if they needed labeling surely they could etch the hilt for a lot cheaper process.
fred
The graphics are likely part of their branding/brand awareness and advertising to distinguish them from the other guys – who might be blue or red or yellow.
I tend to agree about the probable lack of utility on the powder coating – but Lenox for one advertise that their Gold blades are titanium coated – making claims that the coating adds benefits of heat dissipation making them last longer and the teeth stay sharper longer. Dewalt has a black coated blade where they claim 2X life. Freud-Diablo also claims that their “Perma-shield coating protects the blade from heat; gumming; and corrosion.”
glenn
They do it for brand recognition for sure but my guess is that its more for appearance and rust protection for display in shops and up until they are used.
Tim
Very cool article, thanks!
kevin kowalczyk
any chance on getting one of YOUR sawzall blades?
Stuart
Seeing as how there’s just the one… nope!
I don’t think Milwaukee would be willing to let me order 1,000 personalized blades either.
Paul K
I’m kinda surprised by the powder coating process that involves manually hanging each blade on a hook. I really would have expected the spools at one end of the line and finished blades shooting out the other with little to no human intervention along the way.
Benjamen
Like I said that is one of the two powder coating lines. They have the automated line for high volume, but it takes time to switch over that line from product to product.
With the manual line then can quickly switch over to another product to respond to demand.
I didn’t really go into it in this article, because I wanted to focus on how the majority of blades are made. But at many of the steps there are automated lines and there are “High Flex” lines that can switch between products faster. They wouldn’t give us a number but switching an automated line to another product takes somewhere around a day.
Statler
Can you show us the factory where they make the Sawzall itself, not just the blade?
Or is airfare to Donguang too expensive?
Jim Felt
That’s funny.
But really I’d bet that the actual airfare is similar due to the extreme numbers of travelers to the Chinese city v. “where the heck in the least expensive southern state we can build this US factory” location.
Ya think?
Bob
Agreed, their old sawzalls were indestructible. It seems the only big name making their tools in the USA is DeWalt for their high end stuff
Gary
Thanks for the great article and videos. My father worked for Milwaukee for 30 years and was in the manufacturing cell that made Sawzall blades and hole saws. This was before it was moved to MS and his retirement. I worked in his area for a short time as well as a summer job. Seeing the process with robots that used to be done with hands is pretty amazing and it is interesting how the teeth are done now. If I remember right they used to get the metal rolls with the teeth already on them. Looking forward to the next article on hole saws and Ax blades.
Brandon
Really enjoyed this article. Looking forward to the rest of the series.
Ed Frattarelli
I’ve never seen the flush cut blade, I will have to look for that.
Fred Fritts
I just purchased 1 Milwaukee sawall 1301 pruning blade and one Diablo DS0905FG. Both 9″ . There is no doubt in my mind these are the same mfg produced these blades. An exact replica.