How to drill die cast aluminum？

Drilling Die Cast Aluminum

Die cast aluminum is quite machinable, but its abrasive silicon content and tendency to gall require some care. Here's what works:

Drill Bit Selection

• Use sharp HSS (High Speed Steel) or carbide-tipped bits — carbide lasts longer due to the abrasive silicon

• Choose bits with a 118° point angle (standard) or 135° split-point to reduce walking

• Bright/uncoated or TiN-coated bits work well; avoid TiAlN coatings (overkill and can cause sticking)

Speed & Feed

• Run at higher RPM than steel — aluminum cuts best fast

• A rough guide: 200–400 SFM surface speed

• For a ½" bit, that's roughly 1,500–3,000 RPM

• Smaller bits = higher RPM

• Use a moderate, consistent feed pressure — don't force it, but don't let the bit rub/dwell

Lubrication

• Die cast aluminum can gall (weld to the bit), so lubrication is important

• Use WD-40, kerosene, or a dedicated cutting fluid — even a light oil helps

• A squirt bottle works fine for hand drilling

Technique Tips

• Center punch first to prevent walking, especially on curved or slippery cast surfaces

• Use a pilot hole for larger diameters (drill ~⅛" first, then step up)

• Clear chips frequently — aluminum chips pack easily and cause friction/heat

• Peck drill (in-and-out motion) on deeper holes to clear chips

• Secure the part firmly — die castings can have thin walls that flex

Watch Out For

• Porosity — die castings sometimes have internal voids; don't be surprised if you hit one

• Hard spots — flash lines or dense surface skin can be harder; start slow through the skin

• Burrs — aluminum burrs easily; use a countersink or deburring tool to clean up holes after drilling

With sharp bits, the right speed, and a little cutting fluid, die cast aluminum drills very cleanly and quickly.