If you’re in the CNC machining parts game, you’ve definitely run into burrs. Those tiny, sharp, rough edges that pop up on almost every part right off the machine, right? I’ve been running a CNC parts shop for over 8 years now, and let me tell you—burrs used to drive my team nuts. We’d spend extra hours sanding, grinding, or even reworking parts just to get them to a point where a customer would accept them. And let’s be real, no one wants to miss a delivery deadline because of a bunch of tiny burrs. CNC Machining Parts
But here’s the thing: burrs aren’t just an annoyance. They can mess up a whole part’s function, too. If you’re making a part for something like a medical device that has to fit perfectly, a sharp burr could scratch a seal or cause a short in an electrical component. Or if a part goes into a car engine, a loose burr could get stuck in the fuel line and cause a huge headache down the line. Back when I first started, I thought burrs were just par for the course—something you had to deal with after you finished machining. But over the years, we’ve figured out a ton of tricks and methods to handle burrs, both during and after the machining process, that save us time, make our customers happy, and keep our costs from skyrocketing. Today, I want to walk you through what we’ve learned, the methods we use, and the mistakes we used to make that you should avoid.
First off, let’s get real about what burrs actually are. From what we’ve picked up over the years, a burr is basically excess material that gets forced out or torn away from the main part during machining. When the cutting tool—whether it’s a end mill, lathe tool, or drill—cuts through metal, plastic, or whatever material you’re using, it creates a shear zone. If the tool isn’t aligned right, or the speed and feed are off, that shear zone doesn’t break clean. Instead, it leaves a little bit of material stuck to the edge, which is the burr. They come in different types, too. We deal with rollover burrs all the time—those are the ones that curl over the edge of the part, like a tiny roll of excess material. Then there’s tear burrs, which are rough, jagged bits that get ripped off when the tool pulls away, usually on softer materials like aluminum or some plastics. And don’t even get me started on exit burrs—those are the worst, in my opinion. They form when a drill or end mill comes out of the back of the part, and that’s where you get the sharpest, most stubborn burrs. We’ve had customers send parts back just because the exit burr was sharp enough to cut a technician’s finger when they were assembling a product. That’s a no-go, obviously.
Now, here’s the big secret we learned early on: it’s way easier to prevent burrs before they happen than to fix them after. Back in my first year, we’d machine a bunch of parts, then send them straight to the deburring station, spending hours on each batch. But we realized that adjusting the actual machining parameters would cut down on burrs by like 70% right there. Let’s break that down. First, tool selection and condition. If your cutting tool is dull, it’s not going to cut clean— it’ll push material instead of shearing it, which equals more burrs. We check every tool before we put it on the machine, and we replace end mills or drills after a certain number of cuts, depending on the material. For example, when we machine aluminum, we replace a 1/2 inch end mill after about 50 cuts because dull aluminum tools leave way more burrs. Also, tool alignment is non-negotiable. If a drill is slightly off-center, it’ll wobble as it cuts, leaving uneven edges and bigger burrs. We use a tool setter every single time we load a new tool, even if it looks fine to the naked eye. That small step alone saved us so much time on deburring.
Then there’s spindle speed and feed rate. This is where a lot of newer machinists mess up. If your speed is too low, the tool rubs against the material instead of cutting it, which creates heat and pushes material into burrs. If your feed is too high, the tool can’t keep up, so it tears the material instead of shearing it, leading to big, jagged burrs. We test different speeds and feeds for every material and part we make—there’s no one-size-fits-all here. For example, when we machine stainless steel, we run a lower feed rate and a slower speed than we do for aluminum, because stainless is harder and more prone to work hardening. We do a test cut on scrap material for every new part, check the burr size, and adjust until we get the smallest burr possible. It takes an extra 10 minutes per part to test, but that’s way better than spending an hour deburring later. Also, when it comes to exit burrs, using a peck drill instead of a regular drill makes a huge difference. Peck drilling means the drill pulls out of the hole a tiny bit every few millimeters, which breaks up the material that’s forming as the drill exits, so the burr is way smaller. We used to skip peck drilling and wonder why our exit burrs were so bad—now it’s standard for all through-holes, and we barely have to touch those edges after machining.
Another pre-machining trick: using the right workholding. If a part moves even a tiny bit during machining, the tool will catch on the edge and leave a burr. We used to use cheap clamps that would slip when we were machining thick steel, and the resulting burrs were a nightmare. Now we use rigid vises and vacuum chucks for smaller parts, and we make sure the part is seated perfectly before we start the cut. For parts that have a lot of overhang, we add a temporary support—like a small sacrificial tab—at the point where the tool will exit. That support keeps the material from tearing away when the tool comes out, so the exit burr is almost non-existent. We just snap the tab off after machining, and sometimes there’s no need for any deburring at all. It’s a small thing, but it works wonders.
Okay, so what if you’ve already machined the part and you’ve got burrs? You need a solid deburring process, and not all deburring methods are created equal. For years, we tried every method under the sun, and we’ve narrowed it down to the ones that work best for different materials and part types. Let’s go through the ones we actually use, no fancy stuff that’s too expensive for small to mid-sized batches.
First, manual deburring with files and sandpaper. This is the oldest method in the book, and it’s still our go-to for small batches or parts with super complex edges that machines can’t reach. The key here is to use the right tool for the job. For small, tight edges, we use needle files—they’re tiny, so you can get into corners without scratching the main part. For flatter edges, we use diamond files, which are way harder than steel files and last longer, even on tough materials like titanium. We also use sanding sticks and abrasive pads for softer materials like plastic or aluminum, because they won’t leave deep scratches. But manual deburring has its downsides: it’s slow, and it’s easy to miss a tiny burr, which can cause problems down the line. We only use this for parts with very tight tolerance requirements, like those used in aerospace or medical devices, where a tiny scratch could be a big issue.
Then there’s mechanical deburring, which is way faster for large batches. The method we use most here is tumble deburring—wait, no, not just regular tumbling, we use centrifugal disc finishing. Let me explain: we load a bunch of parts into a disc machine with abrasive media—little ceramic or plastic pieces shaped like triangles or cylinders—plus water and a small amount of cleaning soap. The disc spins, so the parts and media are constantly moving and rubbing against each other, which wears down the burrs over a few hours. This is perfect for small, simple parts like screws, connectors, or brackets that don’t have super tight tolerances. It’s hands-off, so our team can work on other things while the machine runs. But here’s the catch: if you have parts with threaded holes, tumbling can get media stuck in the threads, so you have to blow them out with compressed air afterward. We also have to make sure the media isn’t too abrasive for the material—for soft aluminum, we use plastic media, not ceramic, because ceramic would scratch the surface.
For parts that need a little more precision, we use vibratory deburring, which is similar to tumbling but uses vibration instead of rotation. It’s gentler, so it’s better for parts with delicate features, like thin walls or small pins. We use vibratory finishing for parts that go into electronics, where we can’t have any scratches on the surface. We run it for a shorter time than tumbling, usually around 30 minutes to an hour, and it gets rid of burrs without changing the overall shape of the part. That’s important because if you sand a part too much, you can mess up its dimensions, which would make it unusable. We check the dimensions of every part after deburring with a caliper or CMM, just to make sure we didn’t accidentally remove too much material.
Another method we use for tougher burrs, like on thick steel or titanium parts, is grinding. We use bench grinders with a fine grit wheel, but only for parts that don’t have tight tolerances. We wear safety gear—gloves, goggles, face shields—because grinding creates a lot of sparks and flying debris. For parts that have curved edges, we use a flap disc, which is a rotating disc with overlapping abrasive flaps that follow the curve of the part without leaving flat spots. The big downside to grinding is that it’s easy to remove too much material, so it’s not ideal for parts that need to fit exactly. We only use this for heavy, thick parts where the burrs are large and tough.
Wait, and we can’t forget about thermal deburring. That’s a method where we put the part in a sealed chamber, fill it with a mixture of oxygen and natural gas, then ignite it. The heat from the combustion burns off the burrs in a fraction of a second. It’s super fast, perfect for large batches of small parts, and it gets into really tiny crevices where manual deburring can’t reach. But it’s more expensive than other methods, and you have to be careful with it—if you set the temperature too high, it can warp the part or damage coatings. We use thermal deburring for small, simple parts like fasteners, but we steer clear of it for parts with complex geometry or thin walls, because the heat can cause distortion.
Over the years, we’ve also learned what not to do when dealing with burrs. One big mistake we made early on was skipping the pre-machining checks, which led to way more burrs and extra work. Another mistake was using the same deburring method for every part. For example, we once used tumbling on a delicate medical part that had thin walls, and after tumbling, half the parts were warped because the media was too abrasive and the vibration was too rough. We had to scrap the whole batch, which cost us time and money. Now we test a small number of parts with the deburring method before we do the whole batch, to make sure it doesn’t damage the part. We also never use compressed air to blow off burrs, unless it’s to remove loose debris. Compressed air can blow tiny burrs into places you can’t see, and they can get stuck in machinery or hurt someone. We always pick or sand them off if they’re loose.
Another thing we’ve noticed is that different materials react differently to burrs and deburring. For example, aluminum is soft, so it forms big, rollover burrs that are easy to see but can tear easily. We handle aluminum parts with extra care during deburring, because they scratch super easily. Stainless steel is harder, so its burrs are sharper and more stubborn, requiring more aggressive deburring methods like grinding or thermal treatment. Plastics, especially engineered plastics like nylon or PEEK, form very different burrs—they’re more rubbery and don’t break clean, so manual deburring is usually the best option, because mechanical methods can melt or scratch the plastic.
At the end of the day, dealing with burrs is all about balancing prevention and deburring. The best shops don’t wait until after machining to fix burrs—they adjust their processes during machining to minimize burrs in the first place, which saves time and money. For our shop, that means checking every tool, testing parameters on scrap parts, using sacrificial tabs, and choosing the right workholding. When we do have to deburr, we pick the method that’s best for the material, part size, and tolerance requirements, and we always test a small batch first.
If you’re dealing with CNC machining parts and burrs are killing your production time or your part quality, you don’t have to figure it out alone. We’ve been doing this for years, and we know how to handle burrs no matter what material or part you’re working on. We offer custom CNC machining for all kinds of industries, from automotive to medical, and we make sure every part leaves our shop burr-free, no excuses. If you’re looking for a reliable CNC parts supplier that actually knows how to deal with those annoying burrs, feel free to reach out to us to talk about your project. We’re happy to help you figure out the best process for your parts, so you can get high-quality components without the headache of burrs slowing you down.
CNC Turning Service References
- Gillespie, L. K. (1999). Deburring and Edge Finishing Handbook. Society of Manufacturing Engineers.
- Kalpakjian, S., & Schmid, S. R. (2019). Manufacturing Processes for Engineering Materials (7th ed.). Pearson.
- Tonti, R. A. (2002). Burrs: Analysis, Control, and Removal. Society of Manufacturing Engineers.
- Astakhov, V. P. (2006). Metal Cutting Mechanics. CRC Press.
Dongguan Dongchi Precision Technology Co., Ltd.
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