Aluminum is often considered an "easy-to-drill" material because it is softer than steel. However, many drilling problems in aluminum actually come from using the wrong drilling speed.
Too slow, and the cut becomes rough and inefficient.
Too fast, and chips clog, heat builds up, and the material may stick to the drill bit.
So why does aluminum require different drill speeds compared to steel or other metals?
Let's break it down through the most common drilling questions.
Why Is Aluminum Different From Steel When Drilling?
Aluminum behaves very differently during cutting.
Compared to steel, aluminum is:
softer
- more ductile
- more thermally conductive
- more likely to produce long, continuous chips
This changes how heat, friction, and chip formation behave during drilling.
Why Can Aluminum Usually Be Drilled at Higher Speeds?
One major reason is that aluminum dissipates heat relatively well.
Because aluminum transfers heat quickly:
the cutting zone cools more efficiently
the drill bit experiences less thermal stress
higher spindle speeds become possible
This is why aluminum drilling speeds are often significantly higher than steel drilling speeds.
If Aluminum Is Soft, Why Does It Still Cause Drilling Problems?
Softness does not always mean "easy."
Aluminum tends to:
produce long, sticky chips
adhere to the cutting edge
clog drill flutes
This phenomenon is often called chip welding or built-up edge (BUE).
When aluminum sticks to the drill bit:
cutting efficiency drops
surface finish worsens
heat and friction increase rapidly
What Happens If Drill Speed Is Too Low?
Many users mistakenly slow down too much when drilling aluminum.
But excessively low speed can:
increase rubbing instead of cutting
produce poor chip formation
create rough hole surfaces
Aluminum generally cuts more cleanly at higher speeds with proper chip evacuation.
What Happens If Drill Speed Is Too High?
Excessive speed can also create problems.
At very high RPM:
chips may not evacuate properly
friction increases rapidly
aluminum can smear onto the cutting edge
This is especially common with:
dull drill bits
poor flute geometry
lack of lubrication
Why Is Chip Evacuation So Important in Aluminum?
Aluminum often forms long, continuous chips.
If these chips are not removed efficiently:
flutes become clogged
cutting resistance increases
heat builds up quickly
This is why drill bits for aluminum often use:
higher helix angles
polished flutes
geometry optimized for chip flow
Do Different Drill Bit Materials Matter?
Yes.
HSS Drill Bits
Suitable for general aluminum drilling.
Cobalt Drill Bits
Useful for extended production or mixed-material applications.
Carbide Drill Bits
Common in CNC machining and high-speed industrial drilling.
The best choice depends on:
drilling volume
machine rigidity
required speed
Why Are High Helix Drill Bits Often Recommended for Aluminum?
High helix drill bits improve chip evacuation.
They help:
move soft chips out quickly
reduce clogging
lower friction
This is one reason aluminum drill bits often look more "aggressive" than general-purpose steel drill bits.
Is Lubrication Necessary When Drilling Aluminum?
In many cases, yes.
Lubrication helps:
reduce chip adhesion
improve surface finish
lower heat and friction
Even though aluminum transfers heat well, lubrication still improves tool life and drilling stability.
How Do Professionals Choose Drill Speeds for Aluminum?
Professionals usually adjust speed based on:
drill diameter
material grade
machine type
coolant availability
Smaller drill bits generally use higher RPM, while larger diameters require lower speeds.
The goal is always to balance:
cutting efficiency
chip evacuation
heat control
Final Answer: Why Does Aluminum Require Different Drill Speeds?
Aluminum requires different drill speeds because it behaves differently during cutting.
Its softness and high thermal conductivity allow higher speeds, but its tendency to produce sticky chips means chip evacuation and heat control become critical.
Using the correct speed helps:
improve chip formation
reduce clogging
prevent built-up edge
extend tool life
Looking for drill bits optimized for aluminum and non-ferrous metal drilling?
At Ceres Tools, we manufacture high-performance drill bits designed for smooth chip evacuation, reduced friction, and reliable cutting across a wide range of materials.
Contact us to learn more about our drilling solutions and OEM capabilities.