CNC Plasma Table Cutting SWMS

CNC plasma table cutting combines high-amperage electrical arcs, ionised gas at temperatures exceeding 20,000°C, automated gantry motion and the rapid generation of metallic fume, ultraviolet radiation and fine particulate. The work is routinely performed in fabrication workshops, structural steel yards and sheet metal shops across Australia, and falls within the scope of plant operation under WHS Regulation 2011 r203–r214 and hazardous chemical exposure under r35. Because the process simultaneously generates respirable hexavalent chromium (when cutting stainless), manganese fume, ozone, intense UV-C radiation and creates an automated pinch/crush interface, a documented Safe Work Method Statement is mandatory before any operator powers up the table. This SWMS template addresses profile cutting, downdraft and side-draft fume extraction performance, HVAC make-up air balance, consumable changeover and program proving — providing a state-neutral, CIH-reviewed control framework PCBUs can issue, sign on and audit.

Hazards identified

7 hazards covered, sorted by priority.

Control measures

Hierarchy-of-controls order: elimination → substitution → isolation → engineering → administrative → PPE.

1. 1Elimination — Where feasible, substitute thin-gauge profile work to waterjet or fibre laser to remove plasma arc, UV and fume generation entirely from the process.
2. 2Elimination — Remove combustibles, solvents and oily rags from a three-metre exclusion zone around the cutting bed before any program run commences.
3. 3Substitution — Use nitrogen or oxygen-shielded high-definition plasma in place of compressed air to reduce nitrogen oxide and hexavalent chromium generation on stainless work.
4. 4Engineering — Operate a downdraft cutting bed with sectional zone damping interlocked to the torch position, delivering minimum 1.0 m/s capture velocity at the kerf.
5. 5Engineering — Install HEPA-filtered cartridge extraction unit ducted to atmosphere via AS 1668.2 compliant stack with balanced HVAC make-up air supply.
6. 6Engineering — Fit Category 4 light curtains or fixed perimeter guarding around the gantry envelope, interlocked to torch fire and motion per AS 4024.1.
7. 7Administrative — Verify program on dry-run at 10% feed before live cut; complete pre-start checklist covering consumables, water level, extraction amps and HVAC flow.
8. 8Administrative — Restrict access to trained operators holding documented competency; sign on this SWMS at pre-start and after any program, material or consumable change.
9. 9PPE — Issue AS/NZS 1338.1 shade 8–11 auto-darkening helmet, AS/NZS 1337.1 side shields, FR cotton long sleeves, leather gauntlets and AS/NZS 2210.3 boots.
10. 10PPE — Where extraction capture is non-compliant or thin stainless is cut, escalate to AS/NZS 1716 PAPR with P3 cartridge until engineering controls are restored.

Applicable Codes of Practice

Worked example

At a regional structural steel fabrication shop, a leading hand runs the morning pre-start before cutting a 12 mm stainless gusset nest on the CNC plasma table. He opens this SWMS on the workshop tablet and walks the two operators through it line by line. The fume hazard row prompts him to confirm the downdraft extraction amperage is reading within band and the HVAC roller door damper is open — today the reading is low, so he escalates the PPE control to PAPR with P3 cartridges before the cut starts. The UV hazard row triggers a check that the perimeter welding screens are positioned to shield the despatch bay forklift driver. Both operators sign on the SWMS, noting today's material is stainless (hexavalent chromium pathway) rather than the mild steel they cut yesterday. Midway through the run, the cartridge filter differential pressure alarm sounds. The supervisor stops the gantry, returns to the SWMS engineering control row, and follows the documented escalation: isolate, change cartridge, re-verify capture velocity at the kerf with a vane anemometer, then resume. The signed SWMS, the filter change log and the anemometer reading are filed together — providing the audit trail an inspector would expect under WHS Regulation 2011 r299.

Related legislation

• WHS Act 2011 (model)
• WHS Regulation 2025
• AS/NZS 4024 — Safety of machinery

Frequently asked questions