Plasma Cutting Thickness Chart: Amperage vs Plate Thickness
Plasma cutting thickness chart
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| Plasma current | Good-quality cut (edge start) | Production pierce | Typical work |
|---|---|---|---|
| 45 A | up to 10–12 mm | about 6 mm | Thin sheet, signage, HVAC |
| 63–65 A | up to 16–20 mm | about 10 mm | General sheet metal |
| 85 A | up to 20–25 mm | about 12–16 mm | Brackets, base plates |
| 100–105 A | up to 25–32 mm | about 16–20 mm | Fabrication shops |
| 120–125 A | up to 32–38 mm | about 20–25 mm | Thicker structural plate |
| 200 A | up to 50 mm | about 30–32 mm | Heavy plate on gantries |
| 300 A | up to 60 mm | about 40 mm | Heavy fabrication |
| 400 A | up to 80 mm | about 50 mm | Very heavy plate, large pipe |
Typical guidance for mild steel. Stainless steel and aluminum cut thinner. Capacity differs between plasma brands, so we confirm it for the source on your quotation. CNC parts usually start with a pierce, which is roughly half to two thirds of the edge-start thickness.
Three thickness figures, and which one matters
Plasma source makers publish up to three numbers for the same machine. Mixing them up is the most common reason buyers end up with a source that is too small.
Production pierce
The thickest plate the torch can pierce from the top and still give long consumable life. On a CNC table almost every part starts with a pierce, so this is the number to plan around.
Good-quality cut
Also called recommended or quality cut. The thickest plate the source cuts at a useful speed with a clean, nearly square edge, starting from the plate edge.
Severance
The thickest plate the arc can get through at very low speed. The edge is rough and needs grinding. Treat this as an emergency figure, not a production figure.
Why stainless steel and aluminum cut thinner
Stainless steel and aluminum conduct and reflect heat differently from mild steel, and with air plasma the edge oxidizes. Expect a lower practical thickness than the mild steel figure, and a rougher edge on thick aluminum. If you cut a lot of stainless steel, ask for a test cut on your grade, and consider a source that can run nitrogen or argon-hydrogen gas.
Air, oxygen or nitrogen?
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| Plasma gas | Best for | Notes |
|---|---|---|
| Compressed air | Mild steel, stainless steel and aluminum up to medium thickness | Cheapest and simplest. Needs a dryer and filters: water and oil in the air shorten consumable life. |
| Oxygen (shield air) | Mild steel | Faster cutting, smoother and squarer edges, less dross. Used on higher-end sources. |
| Nitrogen or argon-hydrogen | Stainless steel and aluminum, thicker sections | Cleaner, less oxidized edges. Higher gas cost and more complex gas console. |
Duty cycle on a CNC machine
A handheld cutter may stop every few minutes, but a CNC table runs nested parts for hours. Choose a source rated for 100% duty cycle at the current you will use. Running a small source at its limit all day shortens consumable life and slows cutting, so leave some margin: if your thickest daily plate is 20 mm, an 85 A source is tight and a 100–125 A source is comfortable.
When to add oxy-fuel instead of a bigger plasma source
Above about 50 mm, plasma sources become expensive and slow down. For carbon steel plate in the 50–200 mm range, an oxy-fuel torch on the same machine is usually cheaper to buy and run. Oxy-fuel cannot cut stainless steel or aluminum. See our guide to plasma vs oxy-fuel cutting.
Which of our machines fits your thickness
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| Daily plate thickness | Suggested machine and source |
|---|---|
| 0.5–12 mm sheet | P1325 table with a 45–65 A source |
| Up to 25 mm | P1325 or 1500 × 3000 mm table with a 100–120 A source |
| Up to 30–40 mm | Industrial table or P1530 with 160–200 A, or a G2040 / G3060 gantry |
| Up to 100 mm | Heavy-duty gantry with 300–400 A or HD plasma |
| Above plasma range | P1530 (oxy-fuel to 200 mm) or a gantry with oxy-fuel torches |
Ask an engineer
Send your thickest daily plate, the material and your sheet size, and we will recommend a plasma source and table.