How To Cut Aluminum Without Chip Welding

If you cut aluminum, you've probably seen it: a gummy buildup on the carbide, chips fused into the gullets, a rough scored finish, and a blade that suddenly cuts hot and slow. That's chip welding — sometimes called built-up edge — and it's the number-one frustration in non-ferrous cutting. The good news is it's almost entirely preventable once you know what causes it.

What chip welding actually is

Aluminum is soft, sticky, and a great conductor of heat. When a tooth runs hot or can't shed its chip, tiny bits of aluminum cold-weld onto the carbide edge. Once that starts, it snowballs: the welded metal makes the tooth cut worse, which makes more heat, which welds on more aluminum. Left alone, it ruins the finish and can wreck an expensive blade.

Why it happens

• Wrong pitch for the thickness. Too many teeth buried in solid stock pack the gullets so chips can't escape. (See matching tooth pitch to wall thickness.)
• No lubrication. Dry-cutting non-ferrous is the fastest way to weld chips.
• Wrong grind or hook. A flat or high positive hook grabs and smears soft metal instead of shearing it.
• Feed and speed off. Too slow a feed lets teeth rub and heat up; too high an RPM does the same.
• A dull blade. Worn teeth rub instead of cut, and rubbing is heat.

The six fixes

1. Match the pitch to the wall thickness

Fine pitch for thin wall, coarse pitch for solids, so the gullets can always clear the chip. This is the biggest single factor.

2. Use a TCG, negative-hook blade

A triple-chip grind with a negative hook shears soft metal cleanly and meets the work with a controlled, non-grabbing action — exactly what aluminum needs.

3. Lubricate, always

A misting or coolant system is ideal. If you don't have one, a cutting wax stick does the job — touch it to the blade every few cuts. Lubrication is what stops the metal from sticking in the first place.

4. Keep the feed rate steady and confident

Let the teeth take a real chip. A firm, even feed keeps each tooth cutting rather than rubbing; babying the cut builds heat.

5. Don't over-speed the blade

More RPM isn't better with aluminum. Stay within the blade's rated speed; excess surface speed just adds heat.

6. Start sharp, stay clean

Run a sharp blade, and if buildup does start, stop and clean the teeth (a blade-cleaning solution lifts welded aluminum). A clean, sharp edge cuts cool.

Already gumming up mid-job?

Stop and reset: add lubricant, back the RPM down, firm up your feed, and if you're in solid stock with a fine-pitch blade, switch to a coarser pitch. Clean the welded aluminum off the teeth before you continue — cutting through buildup only makes more.

Set yourself up right from the start with the correct blade — browse aluminum & non-ferrous saw blades and grab a wax stick if you're not running a misting system.