Shenzhen Alu Rapid Prototype Precision Co., Ltd.

Yes, we can absolutely drill cast metal — it's done all the time in machining shops, DIY projects, and repairs. Cast iron, cast aluminum, cast steel, bronze, etc., are all drillable, but each behaves a bit differently and requires the right technique to avoid problems.

Key tips by common cast metals:

1.Cast Iron (most common "cast metal" people mean)  

Very drillable, but brittle and abrasive.  

Use sharp HSS or cobalt bits (carbide is even better for production).  

Drill slowly (500–1500 RPM depending on diameter) with steady pressure.  

Use cutting oil or tapping fluid — it makes a huge difference in chip clearing and bit life.  

It often produces fine, dusty chips that pack in the flutes → peck drill (drill a bit, pull out to clear chips) and use a brush or air to clean the hole frequently.  

Work-hardened layers on old castings can be brutal; spot-drill or use a center-cutting end mill first if the skin is tough.

2.Cast Aluminum  

Drills very easily, almost too easily — it gums up bits if you don’t use lubricant.  

Use paraffin wax, WD-40, kerosene, or proper aluminum cutting fluid.  

Higher speeds (2000–4000 RPM) and light feed.  

Polished or 3-flute bits designed for aluminum help prevent buildup.

3.Cast Steel or Ductile Iron  

Behaves more like wrought steel — tougher than gray cast iron.  

Cobalt or carbide-coated bits, moderate speeds, plenty of coolant.

4.Bronze / Brass castings  

Drill like butter with sharp HSS bits and a drop of oil.

General best practices for any cast metal:

Use a sharp bit — dull bits work-harden the surface and make life miserable.

Rigid setup — castings can grab and snap small bits if there’s any flex.

Start with a center punch or spot drill so the bit doesn’t wander on curved/uneven surfaces.

Peck drill on deeper holes to clear chips.

If the casting still has sand or hard spots (common in hobby or reclaimed parts), expect to burn through a couple cheap bits or go straight to cobalt/carbide.