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Stainless steel cuts cleanly with a plasma cutter, but it is less forgiving than mild steel. The correct travel speed depends on thickness, amperage, torch height, air pressure, and the condition of the consumables. Move too slowly and the arc widens the cut, leaves heavy dross, and overheats the edge. Move too quickly and the arc may not fully penetrate, leaving an attached lower slug or an angled cut.

Start With the Cutter’s Cut Chart

Use the cut chart supplied with your plasma cutter as the starting point. A machine’s rated cutting capacity is not the same as its best production speed. For example, a 45-amp cutter may sever 1/2-inch stainless steel, but it will cut 1/4-inch material faster and with a cleaner edge.

Charts usually list amperage, material thickness, travel speed, torch height, and gas pressure. Stainless steel commonly uses clean, dry compressed air, although some industrial machines use nitrogen or other gases for specific edge-quality requirements. Do not copy mild-steel settings blindly. Stainless reflects and retains heat differently, so the same speed can produce a wider, rougher cut.

These are practical starting ranges, not universal settings. A machine with a different torch, duty cycle, or cut chart may require substantially different values. Start near the middle of the range, make a test cut, and adjust from the underside of the workpiece.

How to Set Travel Speed

Set the amperage high enough for the thickness, then adjust travel speed while keeping the torch square to the work. For hand cutting, speed is controlled by how quickly you move the torch. For a CNC table, enter the manufacturer’s recommended feed rate and reduce it in small steps if the cut does not penetrate.

A useful test is to cut a straight line through scrap of the same stainless grade and thickness. The arc should exit below the plate in a controlled stream. On the underside, the cut line should be narrow, and the dross should be light enough to remove with a scraper or wire brush. If the torch is dragging, increase the standoff or use a guide designed for plasma cutting.

When the cut is not penetrating, reduce speed by about 10 percent at a time. Do not immediately raise amperage to the maximum. More current increases heat input and may exceed the consumable’s rating. If the cut is penetrating but has heavy, rounded dross, try a slightly faster speed. If the top edge is melting away or the kerf is unusually wide, the torch may be too close, the amperage may be too high, or the speed may be too slow.

Read the Cut Edge

The direction of the plasma arc creates a small bevel. On a correctly adjusted cut, the top edge is usually close to square and the bottom edge has a slight bevel. Excessive bevel indicates a problem with torch alignment, speed, amperage, or worn consumables.

• Heavy bottom dross: Usually means the travel speed is too slow, the amperage is too low for the thickness, or air pressure is incorrect.
• Stringy dross: Often indicates travel that is too fast or insufficient current. The molten metal is being dragged instead of blown away cleanly.
• Incomplete penetration: Slow down, verify the torch height, and confirm that the machine is actually delivering the selected amperage.
• Wide kerf and excessive top melting: Speed may be too slow, the torch may be too close, or the nozzle may be damaged.
• Uneven or curved cut: The hand motion is inconsistent, the torch is not square, or the plate has shifted.

Torch Height and Air Quality Matter

Travel speed cannot compensate for an incorrect torch height. Follow the manufacturer’s pierce and cutting-height settings. Drag cutting is useful on thin sheet only when the torch is designed for it. On thicker stainless, maintain the specified standoff with a shielded torch or a physical guide.

Use a compressor capable of maintaining the required flow while the plasma arc is running. Moisture and oil contaminate the electrode and nozzle, causing unstable arcs, poor penetration, and inconsistent speed. A water separator, particulate filter, and suitable air dryer are worthwhile upgrades. If your shop compressor cannot maintain pressure, a more expensive cutter will not solve the problem.

For a small garage setup, a quality plasma cutter air filter and water separator may improve results more than buying a higher-amperage machine. Replace the electrode and nozzle when the orifice becomes visibly enlarged, the arc starts wandering, or cut quality changes despite correct settings.

Prepare the Stainless and Protect Yourself

Remove heavy oil, paint, and scale before cutting. Clamp the sheet securely and support it so the kerf does not close around the torch. On thin sheet, use a slatted cutting table or place the work on a suitable grate to limit reflected heat.

Plasma cutting creates ultraviolet radiation, hot metal, noise, and fumes. Stainless steel fumes can contain hexavalent chromium compounds, so use local exhaust ventilation or an appropriate fume extractor rather than relying only on a dust mask. Wear a properly rated auto-darkening plasma cutting helmet, hearing protection, flame-resistant clothing, gloves, and safety footwear. Keep combustible materials away from the cutting area.

When More Cutting Capacity Is Worth Buying

If you regularly cut 1/4-inch or thicker stainless, choose a cutter whose recommended capacity is comfortably above that thickness. A machine operating at its maximum severance rating will be slow and produce more cleanup. For occasional brackets, patches, and thin sheet, a smaller air plasma cutter is usually the cheaper and more practical option.

For repeated production work, a machine with a published stainless cut chart, adjustable amperage, pilot arc, and CNC-compatible torch is worth the extra cost. A 45-amp pilot-arc plasma cutter is often a useful middle ground for general fabrication. Buy a larger unit only when its duty cycle, clean-cut rating, or required thickness justifies it—not simply because the maximum amperage looks impressive.