Drilling in aluminum needs to understand the speed, RPM and feed rate. With high speed steel drill the usual cutting speed for aluminum falls between 80 and 120 meters per minute. Simple rule for cutting speed in aluminum is 200 until 250 feet per minute.
Except that, for high speed steel one commonly uses 200 until 400 SFPM. With such drill it is possible to reach around 100 SFM in aluminum.
Drilling Aluminum: Speed, RPM and Simple Tips
Correctly count RPM are key. The formula for RPM is cutting speed times 4, divided by the diameter of the drill. The edge of the drill travels pi times the diameter for every turn.
For instance, for 1/2 inch drill it travels about 1,5 inches per turn, so 0,125 feet per minute. For 1/4 inch drill in 6061 aluminum the speed is 600 divided by diameter, what gives 2400 RPM. In 6061 aluminum 3/8 inch HSS twist drill uses 4280 RPM.
With 19 mm drill in 6082 you can reach around 2500 RPM, what matches 500 SFM and 141 mm/m at 40 bars with brazed carbide tip.
Aluminum can stick to other metals, for instance high speed steel drill. If the drill or the piece moves, it can get stuck in the bit. Here the weight of the clamp is most important.
Aluminum also forms top cornered chips, that steals power and stops cutting. At the peak of the drill it most smears the material instead of cuts it. Without covering HSS drill too quickly smears and cause galing and weld.
Covered HSS drills for aluminum allow much more fast speeds.
Speed affects the length of the tool. Bigger speed gives fewer holes before sharpening is needed. Slowing down allows more holes before the tool is dull.
Manually drilling you usually use 250, 300 RPM, more slowly than at CNC. A bit of setups bear 7/8 inch hole in aluminum in 10 000 RPM. For 7/8 inch hole in 7075 aluminum minimal RPM of 260 suffices.
For aviod wandering and sticking center punching, piloting, and good cooling necessarily require.
