FC Series
Focus · speed · power · gas
Operator
Why it’s hard — see companion
Before touching settings, confirm two things: that the machine is rated for reflective work at your thickness, and that the optics are clean — reflective metal is the least forgiving material of a dirty protective window. Then work in this order: focus first (you have far less margin here than on steel), gas second (nitrogen, at adequate pressure, for a clean edge), speed third, and power last. Start from the machine’s reflective-material profile — never a steel profile — and prove it on scrap of the same stock and finish before committing a sheet. The pierce, not the cut, is the moment most likely to go wrong.
1 · Before settings: two checks that outrank all four factors.
| Check | Why it comes first |
|---|---|
| Is this machine rated for it? | Back-reflection protection is a designed-in feature, not a universal one, and capability is specified per configuration and power. This is a question to answer before the job, not during it. |
| Are the optics genuinely clean? | A contaminated protective window absorbs energy, heats, and distorts the beam. On steel you might not notice; on copper — where you have little margin to begin with — it’s often the difference between cutting and not. |
Skip these and you’ll spend an afternoon adjusting parameters against a problem that isn’t parametric.
2 · Focus — the least forgiving setting.
Focus position decides how concentrated the beam is at the material. On steel, a small focus error costs you some edge quality. On copper, the same error can stop the cut happening at all — because you started with less absorbed energy, so there’s far less margin to give away.
- Set it deliberately for the thickness, not by carrying over the last job’s value.
- Verify on scrap. A short focus test on the same stock costs minutes and saves sheets.
- Check the sheet is flat. A bowed sheet moves the material relative to focus mid-cut — the effect is identical to setting focus wrong, and it’s easy to misdiagnose as a settings problem.
3 · Assist gas — nitrogen, and enough of it.
Nitrogen is the normal choice for copper and brass. It’s inert, so it clears molten material without oxidizing the cut face, and a bright clean edge is usually the whole reason these metals were specified.
Pressure deserves attention here more than on steel. The kerf is already struggling to stay molten because the metal is conducting heat away; if the gas doesn’t drive that melt clear decisively, it re-solidifies as dross on the underside. Insufficient pressure is one of the most common reasons a reflective cut “almost” works.
Nozzle condition and standoff belong to this same conversation — a worn or damaged nozzle disturbs gas flow and can clip the beam, and neither problem announces itself.
4 · Speed — a balance, not a direction.
The instinct is to slow down when something won’t cut. On highly conductive metals that instinct can make things worse, and it’s worth understanding why:
| Too slow | Too fast |
|---|---|
| Heat has time to spread out of the cut zone into the part — exactly what a high-conductivity metal wants to do anyway. Wider kerf, larger heat-affected zone, worse edge, and possible distortion. | Not enough energy delivered per unit length to get through. Incomplete cuts, or a cut that starts and then fails partway along a contour. |
So there’s a window rather than a direction, and it’s narrower than the equivalent window on steel. Start from the machine’s profile for that material and thickness, and move in small steps.
5 · Power — last, and not as a fix.
Reflective metals do need more power than steel of the same thickness, and that’s legitimate: less of the beam is being absorbed, so more has to be supplied. But power is the last setting to reach for, because turning it up is also the fastest way to make every other problem worse.
If the real issue is a dirty window, more power heats the contamination harder. If focus is wrong, more power widens an already-poor cut. And more power means more energy available to reflect back up the optical path.
The order, and the reason for it
Optics → focus → gas → speed → power. Each step eliminates a cause that would otherwise corrupt your reading of the next. Adjusting power first is the classic mistake: it sometimes appears to work, which buries the real fault until it resurfaces on the next job.
6 · The pierce is the risk moment.
Everything above concerns the cut. The pierce is harder, and on reflective material it’s where problems concentrate — the beam is stationary against an un-pierced, mirror-bright surface, which is the maximum-reflection condition, and molten material is being thrown back up toward the nozzle and window.
Which is why reflective work commonly uses a staged or ramped pierce rather than full power immediately, and why lead-in placement matters even more than usual. Pierce parameters for reflective stock are machine-specific and worth getting from Boss rather than inferring. More on the pierce →
7 · Reading a failed reflective cut.
| What happened | Most likely cause | Check in this order |
|---|---|---|
| Didn’t cut through at all | Not enough absorbed energy reaching the material | Optics cleanliness → focus → is the machine rated for this thickness |
| Started, then stopped mid-contour | Marginal parameters, or heat accumulating in the part | Speed → gas pressure → whether the profile is a steel profile |
| Heavy dross underneath | Melt not being driven clear of the kerf | Gas pressure → nozzle condition and size → speed |
| Wide, ragged kerf | Too much dwell — heat spreading in a conductive metal | Speed up before reducing power |
| Worked on the sample, fails on the sheet | Different finish, alloy, or flatness | Confirm stock matches; check sheet flatness |
| Worked last month, not today | Consumable drift | Protective window and nozzle — before any setting |
8 · Working practice that saves material.
- Test on the real stock. Same alloy, same thickness, same surface finish — a brushed and a mirror sheet of the same alloy behave differently.
- Change one thing at a time. With four interacting settings, changing two leaves you unable to tell which helped.
- Keep a log. Proven settings by material, thickness, and finish are worth more than any published chart, and reflective jobs are exactly where you’ll want to look them up.
- Back off from the edge. Parameters that just cut leave no margin for sheet-to-sheet variation.
- Budget more setup time than the same job in steel. It’s not a failure; it’s the material.
When to stop and ask rather than keep testing
If you’re working near the top of your machine’s capability on copper or brass, more test cuts may not be the answer — the honest limit may be the configuration. That’s a question worth putting to Boss directly: what this specific FC will do on this metal at this thickness. It’s a definite answer, and it’s cheaper than a day of scrap. Ask a specialist →
9 · FAQs
Frequently asked
How to Cut Reflective MetalQHow do you laser cut reflective material?
Confirm the machine is rated for it and the optics are clean, then work focus → gas → speed → power, starting from the machine’s reflective-material profile rather than a steel one. Test on scrap of the same stock and finish before committing a sheet.
QWhat focus position should I use?
Set it deliberately for the thickness and verify on scrap. Focus matters more here than on steel because less of the beam is absorbed, so there’s much less margin for error — and check the sheet is flat, since a bow has the same effect as a wrong focus.
QFaster or slower?
Neither as a rule. Too slow lets a conductive metal spread heat away from the cut, widening the kerf; too fast doesn’t deliver enough energy to get through. The usable window is narrower than on steel — move in small steps.
QWhich gas?
Nitrogen, normally — inert, so it clears melt without oxidizing the cut face and gives the bright edge these metals are chosen for. Pressure matters: the melt has to be driven clear of a kerf already struggling to stay molten.
QDo I just turn the power up?
Power is the last thing to change. Reflective metals do need more of it than steel, but raising it early masks dirty optics or bad focus, widens a poor cut, and puts more energy into back-reflection.
10 · Related in this series.
Part of Fiber & Metal Cutting:
- Reflective metals: the honest story — why these are the hard cases
- The fiber cutting process — the pierce in full
- The parameters you actually set — the general version of this
- Which metals cut well — where these sit on the ladder
Keep exploring
One idea leads to the next.
Metal cutting rewards getting the details right. Follow the rest of the series, or talk it through with someone who runs these systems.