Aluminum Plasma Cutter 101: How It Works and When to Use It in Your Shop

For years, many shop owners thought aluminum was nearly impossible to cut with a plasma cutter. That old story came from the messy results of early conventional machines. Aluminum conducts heat fast, reflects the arc, and has a tough oxide skin. Those things gave ugly cuts, lots of dross, and bad arc starts.

Today, everything has changed. Modern high-definition plasma systems make clean, straight cuts on aluminum all day long. In this guide, we’ll show you what kind of finish to expect, which gases to pick, how to handle water tables safely, and when an aluminum plasma cutter is the smartest tool in your shop.

Can you really cut aluminum with a plasma cutter?

Yes. Absolutely. Modern high-definition machines do it fast and clean. The old problems are gone. Better torches, smarter controls, and improved gas flow solved the heat, reflection, and oxide issues. Shops all over the world now cut aluminum every day with an aluminum plasma cutter.

What kind of cut quality should you expect on aluminum?

You can get near-laser edges on thin sheet and very good mechanical edges on plate. On material up to 6 mm, the surface is often smooth with almost no dross. Thicker plate may have a little bottom dross that knocks off easily. Bevel is usually a bit more noticeable than on steel because aluminum melts at a lower temperature and pulls heat away fast. Keep the right height and speed, and the bevel stays small.

High-definition systems look dramatically better than old conventional plasma. Edges are squarer, smoother, and ready for welding or painting with little extra work.

How to get the best possible cut quality on aluminum

Great cuts services start with the factory cut charts. They tell you the correct amps, height, gas, and speed for every thickness. Follow them first.

After that, make small changes. Raise or lower the torch a little. Speed up or slow down a few percent. Watch the arc. Adjust until the cut looks perfect. Keep gas pressure steady—too low and the arc wobbles; too high and the edge gets rough. Good height control makes a big difference.

Can you plasma cut aluminum on a water table?

You can, but you must be careful. Hot aluminum touching water can create hydrogen gas. Hydrogen explodes easily. Poor ventilation or a closed table can trap the gas and cause a serious accident.

To stay safe:

· Keep the table well-ventilated

· Use an open design so gas can escape

· Don’t cut huge amounts without breaks

· Think about switching to a downdraft table instead

For most aluminum work, a dry or downdraft table is easier and safer.

Can you use water injection or water shield when cutting aluminum?

Yes, and it’s usually safe. Water shield is different from a full water table. It sprays a thin curtain of water around the arc. This cools the cut, gives a cleaner edge, and keeps oxidation low. There’s no big pool of water, so the explosion risk is almost zero.

Many high-end machines pair nitrogen plasma with water shield for medium-thickness aluminum. The results are excellent and cheap to run.

What gases should you use when plasma cutting aluminum?

Plasma cutting gases explained (short version)

You need two gases. Plasma gas makes the arc. Shield gas protects the cut. The right mix controls quality, speed, and cost.

Main plasma gas options:

· Air

· Oxygen

· Nitrogen

· Argon-Hydrogen mixtures (like H-35)

· Sometimes pure hydrogen-based gases

Best gas choices when using an air-only plasma system

Air works as both plasma and shield gas. It’s cheap and always ready. On aluminum up to 6 mm it gives surprisingly good results. You’ll see a little surface oxidation. That’s fine for most jobs. If you need a perfectly clean edge for welding or painting, just grind or brush it lightly.

Best gas choices on multi-gas, high-definition systems

Aluminum less than 5 mm (0.188″) thick

Nitrogen plasma + nitrogen shield gives the cleanest, oxide-free edge. For lower cost, use nitrogen plasma + air shield. Minor discoloration is the only trade-off.

Aluminum 6 mm (1/4″) and thicker

From 6 mm to 25 mm, nitrogen plasma + water shield is usually best. Cleanest edge, lowest cost per foot. Above 25 mm, switch to H-35 or hydrogen-based plasma gas with nitrogen shield. You get much faster speeds and less dross. Never use oxygen on aluminum—it creates heavy oxidation and rough edges.

What else do you need to know before cutting aluminum in your shop?

Quick checklist:

· Pierce at full height first, then drop to cutting height

· Use consumables made for aluminum

· Use good lead-in and lead-out moves to stop notches

· Keep the torch straight up and down—aluminum shows angle more than steel

· Clean the surface well so the arc starts reliably

Aluminum is no longer a headache. Modern aluminum plasma cutter technology from Momaking gives excellent results that often beat laser or waterjet on speed and cost from our factory. If your parts are 3 mm to 50 mm thick and you need fast production with reasonable tolerances, plasma is usually the winner.

For ultra-thin cosmetic work or very tight tolerances, laser or waterjet might still be better. For everything else, grab the aluminum plasma cutter and get cutting.

FAQ

Q: Can an aluminum plasma cutter really replace laser cutting?

A: Yes, for parts 3 mm to 50 mm thick. Modern high-definition aluminum plasma cutters give near-laser edges at 3–10 times the speed and much lower cost per meter.

Q: What’s the best gas for an aluminum plasma cutter on thin sheet (< 6 mm)?

A: Nitrogen/nitrogen for the cleanest edge. Nitrogen/air works great if you don’t mind a little discoloration and want to save money.

Q: Is it safe to run an aluminum plasma cutter on a water table?

A: Only with excellent ventilation and open design. Aluminum plus water can make explosive hydrogen. Most shops use dry or downdraft tables for aluminum and skip the worry.

Q: How thick can an aluminum plasma cutter reliably cut?

A: High-definition systems cut and pierce aluminum up to 50–80 mm with good quality. Thicker than that, waterjet or oxy-fuel usually makes more sense.