Aluminium is soft and easy to cut, but it is sticky — chips weld to the cutting edge and pack the flutes until the hole tears. The best drill bits for aluminium are sharp HSS or cobalt bits with bright, polished flutes and a steeper point angle. Here is what to look for and how to keep the swarf flowing.
What to Look For
Because aluminium is soft, exotic bit materials are not needed — a good HSS or cobalt bit cuts it easily. The real challenge is chip control. Aluminium grabs the cutting edge and forms a built-up edge that smears and tears, so you want polished or bright-finish flutes that shed chips freely, and a slightly steeper point that shears cleanly rather than plowing. Avoid black-oxide bits meant only for steel, and steer clear of dull edges; a clean, sharp lip matters more than anything. A wider helix angle also helps pull chips up and out of deeper holes.
The Best Type of Bit for Aluminium
Choose a sharp HSS or cobalt jobber bit with bright, uncoated flutes. The smooth surface stops aluminium sticking, while a steeper 135° point keeps chips flowing out of the hole instead of welding to the lips.
- Material: HSS or cobalt — aluminium is soft, so sharpness beats hardness.
- Flutes: Bright or polished finish to prevent chip welding and built-up edge.
- Point angle: A steeper 135° point shears cleanly and clears chips.
- Lubricant: A little cutting fluid, kerosene or even paraffin stops sticking.
Technique and Mistakes to Avoid
Run a higher speed with a light, steady feed, and peck the deeper holes — pull the bit out repeatedly to clear the flutes before swarf can pack and weld. Do not let chips build up; once they bind, they tear the hole oversize and can grab the bit hard enough to spin the work. Keep the edge lubricated on all but the shallowest holes, and back off pressure at breakthrough so the bit does not dig into soft aluminium and snatch. Deburr both sides afterwards for a clean, accurate hole. Our USA-made HSS and cobalt bits give the clean, sharp edge aluminium needs to cut without smearing.
Speeds and Sizes
Aluminium likes to be drilled fast, so it is one of the few metals where you can run near the top of your drill’s speed range on smaller bits, backing the RPM down as the diameter grows. Keep the feed light and constant to avoid grabbing. If you plan to tap the hole, size the pilot from a tap drill chart so the threads come out clean in the soft metal. A general-purpose drill set covers the fractional sizes you reach for most on aluminium projects.