Sheet Metal Laser Cutting: Thickness, Assist Gas and Edge Quality

In sheet metal laser cutting, power does not determine the result by itself. Material grade, thickness, surface condition, assist gas, gas purity and pressure, nozzle condition, focus position, speed and machine dynamics all affect whether the part leaves the table ready for the next operation.

Use the existing fiber laser cutting machine power guide for BEIGEMA’s 1–12 kW screening ranges; this guide focuses on gas and cut quality.

Indicative fiber laser power and sheet thickness reference chart
Indicative power-and-thickness chart supplied with the manuscript. Treat every upper limit as configuration-dependent and confirm it by sample cuts.

Choose Assist Gas from the Material and Required Finish

Assist gas removes molten material from the kerf and changes the cutting reaction. The best choice is therefore a production decision, not a simple rule that one gas is always faster or cheaper.

Choose Assist Gas from the Material and Required Finish
Assist gasTypical useMain tradeoff
OxygenCarbon-steel flame cuttingCan increase cutting capability but leaves an oxidized edge
NitrogenOxide-free stainless/aluminum edgesHigh flow and pressure can make gas cost significant
Compressed airSelected carbon steel, stainless and aluminum workLower purchased-gas cost, but air must be clean, dry and suitable for the machine
Argon or mixed gasSpecial materials/applicationsUse only with a qualified process and compatible system

Oxygen can support an exothermic reaction in carbon steel, but the oxide layer may need removal before welding or coating. Nitrogen is commonly chosen where an oxide-free edge matters. Compressed air may reduce purchased-gas cost, yet oil, moisture, inadequate pressure or insufficient flow can damage optics and destabilize the cut.

The available equipment families are listed in the fiber laser cutting machine category.

Thickness Capability Needs Three Different Answers

  • Maximum severance thickness: the machine can separate the plate, but speed and edge quality may be unsuitable for regular production.
  • Stable production thickness: the process can run repeatedly at an acceptable cycle time and consumable life.
  • High-quality thickness: the cut meets the buyer’s tolerance, perpendicularity, dross, roughness and downstream requirements.

A quotation should state which definition is being used. Ask for samples at the normal and maximum production thickness using the exact grade, gas and finish requirement. A generic wattage chart cannot replace that evidence.

For a single-table configuration, review the BM Series 3015 fiber laser.

What Controls Laser-Cut Edge Quality?

Laser cutting process and assist gas illustration
Assist gas, focus, nozzle alignment and motion parameters must be tuned together for the material and thickness.
What Controls Laser-Cut Edge Quality?
SymptomLikely checksPractical response
Dross on lower edgeSpeed, focus, gas pressure/flow, nozzleReturn to approved parameter set; inspect consumables
Wide or tapered kerfFocus position, beam/nozzle centringCheck optics and nozzle alignment
Rough striationsSpeed, power, gas and material surfaceTest one parameter at a time
Burning or overcutSpeed too low or oxygen reaction too strongVerify speed, focus and gas choice
Inconsistent cornersAcceleration, corner power and heat buildupUse controller-specific corner settings
Frequent protective-window damageDirty gas, spatter or bad piercingStop and inspect gas quality and piercing setup

Gas pressure alone is not the cure for a poor edge. Nozzle diameter, standoff, nozzle centring and available gas flow determine what pressure reaches the kerf. Increasing pressure without checking those variables can waste gas and make the result less stable.

A fully enclosed exchange-table option is shown on the BM Series covered fiber laser.

How to Compare Operating Cost

Do not quote one RMB-per-hour or RMB-per-kWh figure without a dated local utility and gas basis. Build cost per part from measured cycle time, nesting yield, electricity, gas consumption, compressor power and maintenance, then add labour and any grinding, oxide removal or rework.

  • Purchased oxygen or nitrogen price and delivery/storage charges.
  • Compressor, dryer, filtration and electricity cost when using air.
  • Nozzles, ceramic parts, protective windows and other consumables.
  • Piercing time, cutting speed, sheet utilization and unattended-running rate.
  • Rejected parts and secondary processing caused by poor edges.

For the wider procurement process, read buying sheet metal machinery from China.

Cut Sample Acceptance Checklist

  • Material certificate, grade, thickness and surface condition match production stock.
  • Machine power, cutting head, nozzle, focus, gas type, purity and pressure are recorded.
  • Dimensions, hole quality, perpendicularity, dross, roughness and heat tint are measured against the drawing.
  • Pierce time, cut time and gas consumption are recorded for cost-per-part comparison.
Illustrative comparison of assist gas effects on laser cut edges
Illustrative comparison of assist-gas effects on laser-cut edges; the final result depends on material, gas, focus, speed and consumable condition.

Sheet Metal Laser Cutting FAQs

Is nitrogen always the best gas for stainless steel?

Nitrogen is widely used for an oxide-free edge, but pressure, flow and cost can be substantial. Confirm finish requirements and compare against qualified air-cutting parameters where appropriate.

Can compressed air damage a fiber laser?

Poorly conditioned air can contaminate or damage the optical path. Use only the pressure, flow, filtration, dryness and oil-control specification approved by the machine and cutting-head supplier.

Why do two machines with the same power cut differently?

Cutting head, beam quality, motion system, parameter library, gas delivery, material and maintenance condition can all change capability and edge quality.

What is the fastest way to verify a supplier's thickness claim?

Request recorded sample cuts using your material and drawing, then measure edge quality and cycle time rather than accepting a maximum-thickness number alone.

Send material details and sample requirements through the BEIGEMA contact page.

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