Plasma Cutting

Plasma cutting uses an ionized gas jet to rapidly cut electrically conductive sheet and plate, balancing high speed and low cost with moderate edge quality.

Overview

Plasma cutting (plasma torch cutting) cuts conductive metals by constricting an ionized gas arc through a nozzle to melt and blow out material. It’s common for steel and stainless plate where speed and throughput matter more than fine edge finish.

Choose plasma for medium-to-thick material, large parts, and cost-sensitive profiles, especially when parts will be welded or machined afterward. It handles dirty or scaled plate well and is widely available in job shops.

Tradeoffs: expect a heat-affected zone (HAZ), some edge taper, and dross that may need grinding. Holes and fine details are limited by kerf width and arc stability, and tolerances are typically looser than laser. Edge metallurgy can matter for fatigue-critical parts or tight-fit features, so plan for secondary ops if needed.

Common Materials

  • Mild steel (A36)
  • Stainless steel 304
  • Stainless steel 316
  • Aluminum 6061
  • Aluminum 5052

Tolerances

±0.010" to ±0.030"

Applications

  • Structural steel brackets and gussets
  • Base plates and equipment mounting plates
  • Weldment kits and tab-and-slot parts
  • Truck/trailer frames and reinforcement plates
  • Stair stringers and architectural plate profiles
  • Repair parts cut from plate stock

When to Choose Plasma Cutting

Plasma cutting fits conductive sheet and plate parts where profile speed and cost drive the decision and moderate edge finish is acceptable. It’s a solid choice for thicker gauges, large outlines, and weldments where edges will be cleaned up or welded. Plan on secondary finishing when tight fits, cosmetic edges, or fatigue-sensitive edges matter.

vs Laser Cutting (CO2)

Choose plasma when you’re cutting thicker plate, larger profiles, or when material surface condition (scale/rust) makes laser less forgiving. Plasma is typically more economical for heavy-gauge work where ultra-fine features and minimal HAZ aren’t required.

vs Laser Cutting (Fiber)

Choose plasma when you don’t need the tight tolerances, small holes, and clean edges fiber lasers excel at, especially on thin-to-medium sheet. Plasma often wins on cost and availability for thick plate and weldment components where post-processing is expected.

vs Waterjet Cutting

Choose plasma when heat input and a small HAZ are acceptable and you want faster cutting at lower cost on conductive metals. Waterjet is better when you must avoid HAZ or need very clean edges without metallurgical change, but it’s typically slower and more expensive.

vs Shearing

Choose plasma when you need non-straight profiles, internal cutouts, holes, or complex perimeters that a shear can’t produce. Shearing is faster and cleaner for simple straight cuts, but it won’t replace contour cutting for parts that need geometry beyond rectangles.

Design Considerations

  • Keep hole diameters at least 1.5–2× material thickness for roundness and repeatability; plan to drill/ream critical holes
  • Avoid tight inside corners; add inside radii at least the kerf width to reduce overburn and improve fit
  • Call out which edges are cut edges vs machined edges; don’t tolerance plasma-cut edges like machined features
  • Allow for HAZ and edge taper on mating surfaces; specify secondary grinding or machining where needed
  • Use common plate thicknesses and note material condition (scaled, pickled, coated) to improve quoting accuracy
  • Add lead-in/lead-out zones away from critical edges; keep critical features off the pierce point