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Expanded metal is a tough cut for a plasma cutter because the sheet is mostly openings. The torch can lose its path across a strand, then fail to re-establish the arc on the next one. The fix is not simply turning up the amperage: use the right setup, keep the torch moving steadily, and plan each cut so it starts and ends on solid metal.
Why expanded metal is tricky to cut
Expanded metal is slit and stretched into a pattern of strands and open diamonds. As the torch crosses an opening, there is no material to carry the arc. The arc may extinguish, sputter, or jump to a nearby strand. The thinner the strands and the wider the openings, the more often this happens.
That makes expanded metal different from solid sheet of the same thickness. A setting that cuts solid 1/8-inch steel cleanly may struggle on expanded metal with strands of similar thickness. Rust, paint, mill scale, poor electrical contact, a worn consumable, or a long torch-to-work distance can make arc loss worse.
Choose the right setup
Check the cutter manual for its rated cutting capacity and recommended amperage for the strand thickness, not the overall thickness of the expanded sheet. Start with the manufacturer’s cut chart. If the sheet is thin, too much current and a slow travel speed can melt away narrow strands and leave a ragged edge. Too little current or excessive speed can cause the arc to drop out or leave uncut bridges.
A drag shield or drag-cutting tip helps hold the torch at a consistent height, if your machine supports it. Without one, follow the manual’s stand-off distance; don’t rest an ordinary nozzle directly on the work. Use a solid, clean area for the work clamp, and place it close enough to the cut for a reliable return path. Clamp the expanded metal so it cannot vibrate or shift, but avoid blocking the torch’s path.
For intermittent cuts, a cutter with pilot-arc capability is often easier to use. The pilot arc helps the torch re-establish an arc after crossing a gap, though it does not guarantee a clean cut through every opening. If you are buying a cutter mainly for this work, compare machines by their stated cut capacity, pilot-arc operation, consumable availability, and duty cycle—not just peak amperage. Browse pilot-arc plasma cutters and check the manuals before choosing.
Pick a method for the cut
| Method | Best for | Trade-off |
|---|---|---|
| Follow one line through the pattern | Long, simple cuts with regular openings | Fast, but the arc may drop out at each gap |
| Cut strand by strand | Short cuts, awkward shapes, or frequent arc loss | More controlled, but slower and more likely to leave uneven edges |
| Use a pilot-arc cutter | Repeated gaps and open patterns | Improves arc recovery, but cannot compensate for poor technique or a weak setup |
For a straight cut, mark the line and plan a path that crosses as many strands as possible rather than travelling through the centers of open diamonds. If a long pass keeps losing the arc, stop and cut in short sections, restarting on a strand. For curves or narrow trim, cutting strand by strand gives more control. Don’t force a continuous cut if the torch repeatedly fails to reconnect; that usually creates a rough edge and wastes consumables.
Make the cut without losing the arc
First, remove coatings near the cut and clamp the work securely. Wear a properly rated welding helmet, gloves, protective clothing, and eye protection for anyone nearby. Plasma cutting throws hot metal and produces fumes; provide suitable ventilation, and keep flammables away from the cutting area. Expanded metal can have sharp edges even before cutting.
Use a piece of scrap with a similar strand size to test your setting and travel speed. Start on a strand, not in an opening. Hold the torch square to the work unless the cut plan calls for a deliberate angle. Once the arc is established, move smoothly across each strand. Avoid pausing over thin material: excess dwell widens the kerf and can melt the strand away.
When the torch reaches an opening, keep the torch moving toward the next strand rather than lingering at the edge. With a pilot arc, the torch may reconnect when it meets metal again. If it does not, release the trigger as directed by the manual, reposition over the next strand, and restart. Don’t swing the torch around while it is firing; that can damage the consumables and produce an unpredictable cut.
Listen to the cut and watch the underside when it is safe to do so. A steady cutting sound and sparks exiting below generally indicate that the arc is penetrating. If sparks stop, the arc sputters, or the cut leaves attached bridges, check for excessive speed, poor grounding, a dirty work surface, worn consumables, or an incorrect stand-off. Change one variable at a time so you can tell what fixed the problem.
Consumables and finishing
A worn electrode or nozzle can make an already intermittent cut unreliable. Inspect consumables for a damaged opening, heavy buildup, or an electrode pit beyond the manufacturer’s limit. Replace them as a set when the manual calls for it; mixing worn and new parts can give inconsistent results. Keep spares on hand if you have a lot of cutting to do. A basic plasma cutter consumables kit is useful only if its parts match your torch.
After cutting, let the work cool before handling it. Remove slag with a suitable hand tool, then inspect for missed bridges and sharp burrs. If the edge will be welded, grind back to clean metal and check that the cut has not narrowed the part more than intended. A grinder can tidy a rough edge, but it cannot restore strands melted away by excessive heat.
For occasional cuts, a standard cutter and a few test passes may be enough; paying extra for features you rarely use is hard to justify. If you regularly cut open grating or expanded metal, pilot-arc operation and easy-to-source consumables can save time and frustration. In either case, matching the setup to the strand size—and restarting deliberately when needed—is more reliable than trying to drag one uninterrupted line through every opening.