Multi-stage Piercing in CypCut

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Multi-stage piercing in CypCut

Piercing (pierce) on the Layer tab is split into several stages; the exact number depends on the CypCut version.

In CypCut the pierce sequence runs from the last stage back to the first — i.e. the first stage you configure executes last.

There are two main piercing modes — Blasting pierce (rough, fast piercing) and Gradual pierces (progressive, smooth piercing). Depending on material thickness they can be combined.

The piercing start in the program is the last stage (Blasting pierce).

Blasting pierce — rough (fast) piercing

The first, rough pierce uses a beam with positive focus (focus pos +) and the same gas pressure (BAR) as for cutting, focused at the center of the metal. The laser continuously heats the metal to melting, forming a crater whose size depends on sheet thickness. The molten metal is quickly blown out by the oxygen stream, forming a pierce hole — its average diameter is about half the sheet thickness. Because of the continuous laser emission, hot metal spatter is heavy, so this method is not suitable for cuts with high precision requirements.

The full process: the focus is set above the material surface and pierce depth grows for rapid heating. Although this method produces lots of molten metal that splashes back onto the workpiece surface, it dramatically shortens piercing time on thick metal. Blasting pierce is suitable for metal up to 8 mm.

Remember: monitoring parameters and the cleanliness of the protective lenses is entirely the operator's responsibility.

On thin metals the spatter is almost invisible.

Gradual pierces — progressive (smooth) piercing

In most cases the quality of Gradual pierces is better than Blasting pierce, but pierce time is significantly longer — though quality improves by orders of magnitude.

For metal from 10 mm and above, combine Blasting and Gradual pierces.

The laser runs in CW or pulsed mode; pulsed mode gives more control over the pierce — high peak power, low duty cycle, and negative focus — to melt and vaporize a small amount of material at a time. The pierce gradually deepens; each pulse pushes fine particles down into the cavity. Compressed air or nitrogen is used as the assist gas to reduce hole widening; oxygen should be watched more carefully because it reacts with carbon steel. The assist-gas pressure (BAR) is lower than the oxygen pressure used during cutting. The deepening takes several seconds; the process does not always complete in a single stage — it depends on metal thickness. The last stage completes the full breakthrough, and if air or nitrogen was used, the assist gas is immediately switched to oxygen for cutting.

Process by stages: after the laser beam irradiates the workpiece, the material surface first heats up (A); then heating gradually deepens (B) → (C) → (D) until breakthrough at the end (E).

This process is not fast, but you get a smooth pierce, preserve the hole geometry as much as possible — a clean entry point, minimal heat-affected zone.

This kind of pierce should start with Blasting pierce and then add Gradual pierces stages.

Summary

For metal up to 8 mm, you can use Blasting pierce: the entry point may be rough, but if hole accuracy is not critical, a single pierce stage is enough.
If laser power is below 3 kW and metal is 3–8 mm, use 2 pierce stages and then add more Gradual pierces depending on thickness.

Gases — what cuts what

Cutting stainless steel with oxygen is irrational. With oxygen the material essentially burns — combustion is high-temperature oxidation and oxygen is the catalyst. So stainless ends up oxidized — you destroy its corrosion-resistant properties — and oxygen does not cool the metal adequately.
Compressed air is best for material up to 3 mm.
For stainless steel, aluminum, and brass up to 6 mm, a single Blasting pierce is usually enough. The main issue is hole accuracy; on thicker metal problems come from poor melt evacuation and unstable cutting.

Typical causes of pierce problems

Long Duty cycle.
High pressure.
High Frequency.
The continuous purge Gas on is left enabled, or Extra blow time is too long.
Extra blow time between Gradual pierces is too short.

Pressure and parameters

Pressure should match cutting pressure — 0.3 to 12 bar, depending on the gas. If gas pressure is too low to evacuate the melt and the speed is the same as cutting speed, hot melt stays in the hole.

Hole diameter increases with pressure and decreases with higher laser power. Raising pressure from 4 to 8 bar shortens pierce time by about 10 %.

Troubleshooting

First, increase Peak power.
Check beam alignment (centering).
Drop the focus to negative.
For piercing, switch to a different gas — matching the main cutting gas.
Increase Extra blow between Gradual pierces stages.
Lower the gas pressure.

If hot metal spatter appears on the first pierce stage:

First drop the frequency (Hz) on the stage where the spatter occurs. E.g. if it is set to 100 Hz, lower it to 10 Hz; on the second stage keep 100 Hz in case 10 Hz isn't enough to break through.
Lower the pressure — e.g. from 1 bar on the first stage to 0.6 bar; on the second stage set it even lower to avoid a "pop", e.g. 0.5 bar.
If that is not enough — drop the duty cycle by 20 % on all stages except the last, drop frequency to 10 Hz, and if the metal is not pierced, raise frequency in 50 Hz increments.

A general-purpose CO₂ laser cannot meet piercing requirements.

Example

Piercing on machines up to 1500 W — even at thicknesses like 8, 10, 12 mm can be configured as a single stage (1 stage). Piercing 20 mm is also possible, but it takes a lot of time: set low power, low frequency, cutting height 20–30 mm — pierce time is about an hour, unsuitable for mass production.

Long-pierce example: 50 Hz, power 100 %, duty cycle 56 %, pierce time on 10 mm — 20–30 s. Still far from optimal.

More than one stage is required for piercing from 10 mm and above or when a fine, clean entry point is needed.