What's inside
As an Amazon Associate I earn from qualifying purchases. This post may contain affiliate links at no extra cost to you.
Stainless steel grating is a demanding plasma-cutting job because it combines relatively thick load bars with open spaces, reflected heat, and many chances for the torch to lose its arc. The best cutter for a shop is not necessarily the machine with the highest advertised amperage. It needs a stable pilot arc, clean compressed air, enough duty cycle for repeated cuts, and a torch that can reach between or across the grating bars safely.
For occasional brackets, drain covers, and small repairs, a 40-amp inverter plasma cutter is often enough. For regular fabrication or grating made from 1/4-inch and thicker stainless, a 60-amp machine gives more useful reserve. If production speed matters, look at an 80-amp class cutter, but also budget for better air filtration, consumables, and a cutting table or fixture.
What to Look for in a Plasma Cutter
Pay attention to three different thickness ratings. The “maximum” rating is usually a slow, rough cut at the machine’s limit. The “recommended” or “rated” thickness is more realistic for clean shop work. A 60-amp cutter may claim a 1-inch maximum cut, yet produce a much better result on 1/2-inch stainless. Stainless also cuts more slowly than mild steel at the same thickness because it does not conduct heat away in the same way.
A machine with a non-high-frequency pilot arc is useful in a general shop. It starts without making high-frequency electrical noise that can interfere with computers, CNC controls, or nearby electronics. A blowback or contact-start torch can work well on a manual cutting table, although it may require more care to avoid dragging the tip through molten metal.
Look for a torch with a shielded tip and a standoff guide. Touching the consumable to stainless can damage the nozzle, cause a double arc, or leave a large blemish on the cut. A machine with adjustable output and a usable air-pressure gauge is easier to tune than one with only a single “cut” setting.
Recommended Machine Sizes
| Machine class | Practical stainless capacity | Best use | Main limitation |
|---|---|---|---|
| 30–40 amp | Up to about 1/4 inch cleanly | Light grating, tabs, small repair work | Slow on thicker load bars and limited duty cycle |
| 50–60 amp | About 3/8 to 1/2 inch cleanly | Most small and medium fabrication shops | Needs good air and adequate 240-volt power for sustained work |
| 80 amp | About 5/8 inch cleanly, depending on design | Repeated cuts and heavier grating | Higher cost, larger power supply, and more consumable use |
| 100 amp or more | Heavy plate and high-volume production | Large fabrication shops and mechanized tables | Overkill for occasional manual grating cuts |
For most shops, a 60-amp 240V plasma cutter is the sensible middle ground. It has enough output for common stainless grating while remaining portable and less expensive to operate than a large industrial unit. A cheaper 40-amp cutter is fine if the material is 3/16 inch or thinner and you only make a few cuts at a time.
Air Supply and Electrical Requirements
Compressed air quality has a direct effect on cut quality. Water or oil in the air line contaminates the electrode and nozzle, causing an unstable arc, excessive dross, and premature failure. Use a dedicated separator and filter close to the cutter. Many machines require roughly 4.5 to 6 cubic feet per minute at 60 to 75 psi, but check the manual rather than sizing the compressor from the free-air-delivery number on its label.
A small 6-gallon compressor may run a light 40-amp cutter for short cuts, but it will cycle constantly during a long layout. A 20- to 30-gallon compressor with at least 6 CFM at the required pressure is a more comfortable starting point for a 50- or 60-amp machine. Let the compressor recover before beginning a long cut. Falling pressure makes the arc wander and can leave uncut sections in the load bar.
Many 60-amp cutters need 240 volts to reach their full output. A 120-volt machine is convenient for field repairs, but it generally cuts slower and may have a lower duty cycle. Use the correct breaker, wire size, and extension cord. An undersized cord can cause voltage drop, nuisance trips, and poor arc performance.
How to Cut Stainless Grating Cleanly
Support the grating firmly, but leave room for the arc and molten metal to escape. Cutting directly on a solid steel table reflects heat and can damage the work surface. Slats, a water table, or sacrificial expanded metal under the work reduce reflected arc energy. Keep the torch perpendicular to the top surface unless the cut is intentionally beveled.
Mark the cut on the top face and use a straightedge or a magnetic guide where practical. Start at an edge when possible. If you must pierce, start with the torch angled slightly away from the finished area, then bring it upright after the pierce is complete. This keeps the hot blowback from striking the nozzle.
Use the manufacturer’s amperage and travel-speed chart as a starting point. On stainless grating, cutting too slowly usually creates a wide kerf, heavy dross, and more heat distortion. Cutting too fast leaves a partial cut or a visible lag line on the underside. A clean cut has a narrow kerf and a slight, consistent bevel; it should not require force to separate.
For repeated cuts, a plasma cutting guide and standoff can improve consistency. Do not use a guide that blocks the shield cup or forces the torch too close to the work. The open sections of grating can also interrupt motion, so maintain a steady travel speed as the torch crosses each bar.
Consumables, Safety, and Maintenance
Expect consumables to wear faster when cutting grating. The torch repeatedly passes over edges, gaps, and hot material, which can erode the nozzle and electrode. Keep spare electrodes, nozzles, and shield cups on hand. Replace them when the nozzle orifice becomes oval, the arc starts wandering, or the electrode pit is visibly deep. Continuing with damaged consumables produces worse cuts and can damage the torch.
Stainless cutting creates fine metal dust and fumes that should not be treated as harmless. Use local exhaust or outdoor ventilation, keep your face out of the plume, and wear a properly rated respirator when ventilation cannot control exposure. Wear a plasma-rated face shield or welding helmet with the appropriate shade, leather gloves, nonflammable clothing, and hearing protection. Secure the grating before cutting; loose bars can shift suddenly when the final connection is severed.
If the shop cuts stainless grating weekly, spend more on a 60- or 80-amp cutter with a replaceable torch, good parts availability, and a real duty-cycle rating. If the job is occasional and the grating is thin, a 40-amp pilot-arc plasma cutter is usually the better value. The machine matters, but clean air, correct travel speed, firm support, and fresh consumables matter just as much.