If you’ve ever tried drilling aluminum, you know it’s not like drilling through wood or mild steel. Too many drill bits end up snagging, leaving burrs, or even melting into the metal, and that’s a frustrating mistake I’ve seen more new fabricators and hobbyists make than I care to count. As someone who’s spent 12 years as a drill bit supplier, working side by side with machinists, DIYers, and aerospace part manufacturers, I’ve learned that aluminum’s unique properties demand a specific kind of drill bit—one that’s built to handle its soft, gummy nature without ruining your workpiece. Let’s break this down, no jargon overload, just real-world answers that’ll save you time, scrap, and cash. Drill Bits
First, let’s talk about why aluminum is so tricky to drill, because if you understand the problem, picking the right bit makes way more sense. Unlike steel, which is hard and chips clean when you cut it, aluminum is soft, ductile, and tends to form long, stringy chips that can wrap around the bit instead of falling away. Those stringy chips often get caught between the bit and the workpiece, causing friction, which melts aluminum easily—think of that gunky, cloudy residue you might have seen on a drilled hole before. Aluminum also has a low melting point, around 1,220°F, way lower than steel’s ~2,750°F, so heat is your enemy here. Add in that aluminum works hardens if you push too slowly or apply too much force, and you’ve got a material that punishes generic drill bits designed for steel. That’s why grabbing any old bit from your garage toolbox is almost always a bad call for aluminum.
Now, what actually works? The first rule is: use a bit made specifically for aluminum, or at least a high-quality general-purpose bit engineered to handle soft, non-ferrous metals. Let’s start with the most common and reliable type: high-speed steel (HSS) bits, but not just any HSS. Look for bits with a cobalt additive—M35 or M42 grade HSS, specifically. Cobalt adds hardness and heat resistance, which is critical for aluminum’s low melting point. I recommend M35 for most hobbyists and small to medium fabrication shops; it’s durable enough to handle repeated drilling in 6061 or 7075 aluminum without wearing down fast, and it’s priced way more reasonably than M42. M42 is for heavy industrial use, drilling thick aluminum plate or high-strength 7075, where you need extra heat resistance, but most folks won’t need to splurge on that.
Wait, but not all HSS-aluminum bits are the same. The geometry of the bit is non-negotiable here. The cutting point, or the angle at the tip, is a big one. Generic steel drill bits have a 118-degree included angle, but for aluminum, you want a shallower 90-degree to 100-degree angle. A steeper angle digs too deep into the soft aluminum, causing those stringy chips I mentioned earlier, and increasing friction. A shallower angle lets the bit slice through the aluminum cleanly, producing shorter, easier-to-remove chips. The flutes—those spiral grooves that carry chips away from the hole—are another key feature. For aluminum, you want bits with wider, deeper flutes. Narrow flutes get clogged with stringy aluminum chips, leading to overheating and a ruined hole. I always tell customers: if the flutes look thin and tight, put it back. Wide, open flutes = less clogging, smoother drilling.
Next up: solid carbide drill bits. These aren’t cheap, but they’re a game-changer for heavy-duty, high-volume work. If you’re drilling holes in thick aluminum (1 inch or more) or running a production line where you need to drill hundreds of holes a day, carbide bits are worth every penny. Carbide is way harder than HSS, so it stays sharp way longer under high heat. The best carbide bits for aluminum have a polished coating—think titanium nitride (TiN) or diamond-like carbon (DLC)—that reduces friction even more, stopping chips from sticking. Just a heads up: carbide is brittle, so you don’t want to use it for hand drilling or small, irregular jobs; it’s better suited for precision CNC work or heavy press drilling.
There’s also a type called step drill bits, which I swear by for aluminum sheet metal. These are cone-shaped bits that drill multiple holes of increasing size in one pass, perfect for creating pilot holes for fasteners or holes that need to be deburred at the same time. Their geometry means less contact with the workpiece, less heat, and no burrs when you’re done—something most standard bits can’t pull off. I recently had a customer in the electrical industry who was drilling 1/2 inch holes in 16 gauge aluminum for circuit panel mounts; he was using regular HSS bits and getting burrs so bad he had to deburr every hole by hand. Switched to step drill bits, and that extra step process cut his deburr time by 80%. That’s the kind of real win I love hearing about.
Now, what drill bits should you avoid for aluminum? Let’s get that out of the way first, because it’s easier to steer clear of mistakes. First, any old cheap drill bit you picked up at a dollar store or big box store’s discount bin. Most of those are low-grade HSS, no cobalt, with the wrong 118-degree tip angle, and they’ll chew through aluminum like butter for 10 seconds before they dull or melt. Then there are masonry bits—never, ever use a masonry bit on aluminum. Those are designed for concrete, with a different tip geometry that will gouge and grab the metal, causing it to warp or crack. And skip self-tapping screws or sheet metal bits unless they’re specifically labeled for aluminum; many generic sheet metal bits have a point that’s too sharp, leading to over-penetration and distorted holes.
Wait, but buying the right bit is only half the battle—how you use it matters just as much. I’ve had customers call me saying “your bits are garbage” when really they were drilling too fast or too slow. Let’s talk drilling speeds. For aluminum, you want way higher RPM than you would for steel. For HSS bits, start at 1,000 to 2,000 RPM for 1/4 inch aluminum, and go up to 500 to 1,000 RPM for 1 inch plate. For carbide bits, you can go even higher—up to 5,000 RPM for thin sheet, because carbide handles heat better. Feed rate is another big one: you want a steady, consistent feed, not pushing so hard that the bit grabs, but not letting it drag. If you feel the bit slowing down or the chip turn into a long, stringy mess, adjust your feed or RPM. Also, always use a lubricant, even if it’s just a little cutting oil or even WD-40, to reduce friction and cool the bit. I’ve seen people drill dry for convenience, but that’s a surefire way to get melted aluminum stuck to the bit and a ruined hole.
What about different types of aluminum? Because not all aluminum is the same. 6061 aluminum is the most common, used in everything from bike frames to window frames, and it’s pretty easy to drill—most HSS bits work fine here. 7075 aluminum is high-strength, used in aerospace and automotive parts, and it’s way more ductile, so it’s more prone to work hardening. For 7075, I always recommend M35 cobalt HSS or carbide bits, a slightly slower feed rate, and extra lubrication. Thin aluminum sheet (under 1/8 inch) is another animal—you can easily punch through and bend the sheet if your bit isn’t sharp or if you don’t have a backer. I always suggest placing a scrap piece of wood or another aluminum sheet behind your workpiece when drilling thin stock, to prevent the bit from grabbing and tearing the back of the hole.
Over the years, I’ve worked with everyone from a hobbyist building a custom kayak to a major aerospace contractor, and the number one mistake I see is people overcomplicating things. You don’t need a $50 carbide bit for every single aluminum drilling job. For small, occasional projects, a good quality M35 cobalt HSS drill bit (they run $5 to $15 each, way cheaper than wasting a whole piece of aluminum) will do the job perfectly. For production work, step up to carbide. The key is matching the bit’s geometry and material grade to your specific job, not just grabbing whatever is on the shelf.
If you’re still not sure which bit is right for your project, don’t guess. That’s why I’m here. I’ve spent years helping customers sort through their drilling needs, and I can walk you through which bit will save you time and money, whether you’re drilling 10 holes for a home project or 10,000 holes for a commercial order. You don’t have to deal with melted aluminum, burrs, or dull bits anymore. Reach out to my team to discuss your drilling requirements, and we’ll help you find the perfect drill bits for your aluminum projects.
Other Abrasive Products References
- Kalpakjian, S., & Schmid, S. R. (2014). Manufacturing Processes for Engineering Materials. Pearson Education.
- “Drilling Aluminum: Best Practices and Tool Selection.” Modern Machine Shop, 2022.
- “Non-Ferrous Metal Machining Guide.” Kennametal Inc., 2021.
- DeGarmo, E. P., Black, J. T., & Kohser, R. A. (2020). Materials and Processes in Manufacturing. John Wiley & Sons.
Zhenjiang Cutech Tools Co., Ltd.
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