What Metals Can You Cut with a Manual Plasma Cutter?

One of the biggest advantages of plasma cutting over other cutting methods is its versatility across different metals. Where oxy-fuel cutting is limited to mild steel, and grinding is slow on anything thick, a manual plasma cutter handles virtually any electrically conductive metal — from thin sheet aluminium to heavy stainless steel plate — with the same machine and the same compressed air supply.

This guide covers the metals you can cut with a manual plasma cutter, how each material behaves under the plasma arc, and what to adjust to get the best results. For a full introduction to the process, see our Complete Guide to Plasma Cutting.

The Golden Rule: Electrical Conductivity

Plasma cutting works by forming an electrical arc between the torch electrode and the workpiece. This means the only hard requirement is that the material conducts electricity. If it’s conductive, a plasma cutter can cut it.

Plasma cutting cannot be used on non-conductive materials such as wood, plastic, stone, glass or ceramic. For those materials, waterjet or laser cutting are the appropriate processes.

Mild Steel

Mild steel is the easiest and most forgiving material to plasma cut. The plasma arc reacts well with the iron content in mild steel, producing fast, clean cuts with consistent edge quality across a wide range of thicknesses. It is the reference material for all plasma cutter capacity ratings — pierce capacity, cut capacity and maximum severance figures quoted by manufacturers are always based on mild steel.

• Cut behaviour: fast, predictable, clean edge with minimal dross at the correct travel speed
• Gas: compressed air works well for manual cutting; oxygen gives faster speeds and better edge quality on CNC systems
• Amperage: standard — use the machine’s recommended settings for the thickness being cut
• Watch for: dross on the underside is usually a sign of incorrect travel speed — too slow produces heavy bottom dross; too fast produces a ragged, incomplete cut
• Spark test: sparks should eject straight down through the cut. Sparks trailing backwards means you’re moving too slowly; sparks spraying forward means you’re moving too fast

Painted, Primed and Coated Mild Steel

Plasma cutting handles painted, primed and lightly coated mild steel well — far better than oxy-fuel, which requires a clean bare metal surface. The plasma arc burns through most surface coatings without significantly affecting cut quality. Heavily galvanised steel (zinc-coated) can be cut but produces zinc oxide fumes — always ensure adequate ventilation or fume extraction and wear appropriate respiratory protection.

Rusty or Scaled Steel

Plasma cutting works on rusty or scaled steel that would cause problems for other processes. Light to moderate surface rust has minimal effect on cut quality. Heavy scale or thick rust may affect arc stability slightly — if cut quality degrades, clean the surface in the cut area or increase amperage slightly.

Stainless Steel

Stainless steel cuts cleanly with a manual plasma cutter and compressed air across all the thickness ranges the Cutmaster range covers. The cutting speed on stainless is slightly slower than on equivalent thickness mild steel, due to stainless steel’s lower thermal conductivity and higher melting point.

• Cut behaviour: clean cut, slightly slower than mild steel at equivalent thickness. Some discolouration (heat tint) on the cut edge and face is normal with compressed air
• Gas: compressed air is standard for manual cutting. Nitrogen produces a cleaner, less oxidised cut edge — worth using when cut edge appearance is critical (food-grade fabrication, architectural work)
• Amperage: similar to mild steel at equivalent thickness, or slightly higher
• Watch for: heat tint (blue/gold discolouration) on the cut face is normal when using compressed air. If this is unacceptable for the application, switch to nitrogen gas or use a post-cut passivation treatment
• Earth connection: a good, direct earth connection to the plate is especially important on stainless steel. A poor earth causes arc wander and inconsistent cut quality

Aluminium

Aluminium is fully plasma-cuttable with compressed air and is a common everyday material for fabrication shops, automotive work and construction. However, aluminium’s physical properties mean it behaves differently under the plasma arc than steel, and a few adjustments are needed to get clean results.

• Cut behaviour: slightly slower than mild steel due to aluminium’s higher thermal conductivity, which spreads heat away from the cut zone rapidly. Requires higher amperage than equivalent thickness mild steel
• Gas: compressed air works well for most manual cutting. Nitrogen improves cut edge quality on thicker sections
• Amperage: increase by approximately 10–15% compared to equivalent thickness mild steel settings
• Travel speed: aluminium’s high thermal conductivity means heat builds up quickly if you slow down. Maintain a consistent travel speed — pausing or slowing significantly causes the molten metal to cling to the edge rather than blow clear
• Watch for: soft, sticky dross on the underside is the most common aluminium cutting problem — usually caused by too slow a travel speed or insufficient amperage. Increase speed or amperage and retest on scrap
• Surface preparation: aluminium naturally forms an oxide layer. While plasma cutting handles this without special preparation, a heavily oxidised surface may affect arc initiation. Lightly brushing the cut line with a stainless steel wire brush improves consistency on heavily weathered material

Copper and Brass

Copper and brass can be plasma cut with a manual cutter, but their high thermal conductivity — even higher than aluminium — makes them more challenging. The plasma arc has to work harder to maintain enough heat in the cut zone to melt and expel material cleanly.

• Cut behaviour: slower than steel or aluminium; the cut edge tends to be rougher and may require more finishing work
• Amperage: use higher amperage than for steel at the same thickness, and reduce travel speed to compensate for the heat dissipation
• Consumables: copper and brass are harder on consumables than steel. Use fresh consumables and inspect the electrode and nozzle more frequently
• Fumes: cutting copper and brass produces copper oxide and zinc oxide fumes respectively. Both are hazardous with prolonged exposure — ensure adequate fume extraction and wear appropriate respiratory protection
• Practical note: for occasional cuts on copper or brass, a plasma cutter is a practical solution. For high-volume or precision copper cutting, a waterjet or laser may deliver better results with less finishing work

Titanium

Titanium is electrically conductive and can be plasma cut. It is relatively straightforward to cut with compressed air, though the cut edge will oxidise (turn blue/gold) due to titanium’s reactivity at high temperatures. For aerospace or medical applications where the cut edge integrity matters, post-cut machining is typically required regardless of the cutting method used.

• Cut behaviour: cuts reasonably well at similar settings to stainless steel of equivalent thickness
• Watch for: edge oxidation is normal and unavoidable with air plasma. Not an issue for most structural or fabrication applications

Cast Iron

Cast iron can be plasma cut, though it is more brittle than steel and the cut edge is rougher. The high carbon content of cast iron affects the plasma arc slightly, and the material is prone to cracking if thermal shock is severe.

• Cut behaviour: produces a usable cut but with a rougher edge than mild steel. Expect more post-cut finishing
• Watch for: avoid rapid temperature changes around the cut — on thick or complex castings, consider preheating the area around the cut to reduce thermal shock risk

What Plasma Cutting Cannot Cut

Plasma cutting requires electrical conductivity. It cannot be used on:

• Wood, MDF, plywood
• Plastic, rubber, fibreglass or composites
• Stone, concrete or masonry
• Glass or ceramic
• Non-conductive coatings (the underlying metal can be cut, but thick non-conductive coatings may prevent arc transfer)

Material Comparison: Manual Plasma Cutting at a Glance

The ESAB Cutmaster Range: Built for All Metals

All three models in the ESAB Cutmaster range cut mild steel, stainless steel and aluminium with compressed air as standard. The right model depends on the thickness you need to cut:

• Cutmaster 30+ — 10mm pierce / 12mm cut capacity. Ideal for thin to medium sheet work in mild steel, stainless and aluminium.
• Cutmaster 50+ — 16mm pierce / 25mm cut capacity. The all-rounder for fabrication shops cutting a mix of mild steel, stainless and aluminium plate.
• Cutmaster 70+ — 20mm pierce / 30mm cut capacity. For heavier plate work and applications where higher amperage gives better results on stainless and aluminium.

Not sure which model is right for your material and thickness? See our guide to Tips for Buying a Manual Plasma Cutting Machine or speak to an ESAB specialist.