How to Cut Expanded Metal and Grating with a Plasma Cutter

Cutting expanded metal, grating, mesh or any open grid material with a standard plasma cutter is a frustrating experience. Every time the arc crosses an open gap between strands, it loses contact with the workpiece and extinguishes — then has to restart for the next strand. On a basic plasma cutter, this means repeated arc interruptions, excessive nozzle wear and poor cut quality. On the Cutmaster range, a dedicated grate cutting mode solves this problem completely.

This article explains what grate cutting mode is, why it matters, how to use it and when to switch between normal and grate cutting on the ESAB Cutmaster 30+, 50+ and 70+.

For a full overview of the Cutmaster range and manual plasma cutting, see our Complete Guide to Plasma Cutting.

The Problem with Cutting Expanded Metal on a Standard Plasma Cutter

When you cut solid plate with a plasma cutter, the arc maintains continuous contact with the workpiece throughout the cut. The plasma arc is stable, the consumables wear at a normal rate and cut quality is consistent.

Expanded metal (also called grating, mesh or grid) is different. The material has open voids between the metal strands. As the torch moves across the surface, the arc repeatedly loses contact with the metal each time it crosses a gap, then must re-ignite when it reaches the next strand.

On a standard plasma cutter without grate mode, this creates several problems:

• Arc extinction — the arc extinguishes in the gaps and must restart on each strand. At high cutting speeds, this causes the machine to struggle to maintain the arc continuously, resulting in missed cuts and incomplete separation of strands
• Excessive consumable wear — every arc restart puts additional stress on the electrode and nozzle. Cutting expanded metal without grate mode can reduce consumable life dramatically — sometimes by 50% or more compared to plate cutting
• Unstable arc and poor cut quality — the repeated on/off cycle creates an inconsistent arc that produces ragged cut edges and spatter
• Machine stress — repeated arc restarts create voltage spikes that increase wear on the power supply components over time

What Is Grate Cutting Mode?

Grate cutting mode (also called expanded metal mode) is a dedicated operating mode available on all three ESAB Cutmaster models — the 30+, 50+ and 70+. When activated, it changes how the machine manages the plasma arc when it loses contact with the workpiece.

In normal plate cutting mode, when the arc extinguishes, the machine requires the operator to release and re-press the trigger to restart. In grate cutting mode, the machine automatically maintains the pilot arc in the gaps between strands and instantly re-transfers the cutting arc the moment it detects conductive material again. This is sometimes referred to as auto-pilot restart.

The result:

• The arc re-establishes instantly as each new strand is reached, without any action from the operator
• The torch moves continuously across the expanded metal without stopping
• Consumable life is preserved because the arc does not fully extinguish and restart on every gap — the pilot arc is maintained at reduced power between strands
• Cut quality is consistent across both the metal strands and the transition points

When to Use Grate Cutting Mode

Switch to grate cutting mode any time you are cutting material with gaps or voids that the arc will pass over during the cut. Common applications include:

• Expanded metal / diamond mesh — the most common grate cutting application. Widely used in fabrication of walkways, platforms, guards, screens and grilles
• Bar grating and floor grating — welded or swaged steel grating for industrial flooring, stair treads and drain covers
• Chain link fencing — occasional cutting of chain link fence panels
• Perforated sheet — sheet metal with a regular pattern of holes. The arc extinguishes over each hole, so grate mode applies
• Stacked plate with gaps — cutting through multiple layers of material with air gaps between them
• Gouging — some operators also use grate mode for gouging applications, as it maintains the pilot arc when the torch manipulates away from the base metal momentarily

When to Stay in Normal Plate Mode

For all solid plate and sheet cutting — including mild steel, stainless steel, aluminium and any continuous solid surface — use normal plate cutting mode. There is no benefit to grate mode on solid material and it uses slightly more energy to maintain the pilot arc between strands.

How to Switch Between Plate and Grate Mode on the Cutmaster Range

Switching between normal and grate cutting mode on the Cutmaster 30+, 50+ and 70+ takes seconds and requires no tools or settings adjustments beyond the mode selection itself.

1. Press the mode selection button on the TFT LCD display panel
2. Use the glove-friendly adjustment knob to navigate to the cutting mode option
3. Select Grate (expanded metal) mode from the menu — the display confirms the active mode
4. Cut as normal — the machine handles arc re-ignition automatically across gaps
5. To return to plate cutting, navigate back to the mode menu and select Normal

The mode selection is accessible directly from the main display screen. You do not need to power down or adjust any other settings. Amperage, air pressure and torch settings carry over between modes.

Tips for Cutting Expanded Metal and Grating

• Use grate mode — always — even for short cuts on expanded metal, grate mode significantly extends consumable life. There is no reason not to use it.
• Maintain a consistent travel speed — moving too slowly over expanded metal causes heat to build up on the individual strands, which can warp thinner material. Keep the torch moving at a steady pace.
• Keep the standoff consistent — the torch-to-work distance affects how reliably the arc re-transfers across gaps. Use the standard standoff for your consumable type and maintain it throughout the cut.
• Inspect consumables before long grate cutting runs — while grate mode dramatically reduces consumable wear compared to standard mode, expanded metal cutting is still more demanding than flat plate. Start with fresh or lightly used consumables for extended grate cutting sessions.
• Air quality matters — clean, dry compressed air is as important for grate cutting as for plate cutting. Moisture in the air supply disrupts the pilot arc and causes inconsistent re-ignition across gaps.
• Support the material — expanded metal and grating can flex and move during cutting. Support the workpiece securely to maintain a consistent standoff across the cut.

Grate Mode and Consumable Life: The Numbers

The difference grate mode makes to consumable life on expanded metal is significant. Without grate mode, every gap crossing is a full arc extinction and restart — the same stress on the electrode as starting a new cut. On a typical expanded metal cutting task with hundreds of gaps per metre of cut, this translates to electrode and nozzle wear that would occur in a fraction of the normal plate cutting lifespan.

With grate mode active, the pilot arc is maintained between strands. The electrode hafnium insert and nozzle orifice are not subjected to the same restart stress on every gap. The ESAB Cutmaster Black Series consumables are engineered for extended life in all cutting modes — and the combination of Black Series consumables with grate mode active gives you the best possible consumable performance on expanded metal work.

Grate Mode on the ESAB Cutmaster Range

Grate cutting mode with auto-pilot restart is available as standard on all three Cutmaster models:

• Cutmaster 30+ — grate cutting mode accessible via TFT LCD display. Ideal for lighter expanded metal and mesh up to 10mm strand thickness.
• Cutmaster 50+ — grate cutting mode with auto-pilot restart. Handles heavier grating and expanded metal with ease at 50A output.
• Cutmaster 70+ — grate cutting mode with auto-pilot restart. For heavy bar grating, industrial flooring and any high-volume expanded metal cutting application.

All three models also feature an automatic post-cut air purge that cools the torch and extends consumable life after the trigger is released — another feature that works in your favour on grate cutting tasks where the torch is frequently stopping and starting at the edges of panels.

Get in touch with an ESAB specialist if you have questions about the right Cutmaster model for your expanded metal or grating cutting application.