1064 nm Fiber Laser Basics: Why It Works on Steel, Aluminum and Brass

The 1064 nm fiber laser​ became the default tool for industrial marking for one reason: it is the wavelength that metals absorb most efficiently. The beam is generated in a fiber source​ (Raycus, Max or JPT), delivered through a flexible optical fiber to the galvo head, and focused by an F-theta lens​ to a 30–50 µm spot. Unlike a CO₂ laser (10.6 µm), which reflects off bare metal, or UV (355 nm), which works by photochemical bond breaking, 1064 nm heats the metal surface​ because free electrons absorb the photon energy. That is why one wavelength handles stainless steel, carbon steel, aluminum, brass, copper, titanium and precious-metal alloys​ equally well. Marking needs no consumables, draws <0.5 kW​ from a 220 V/50 Hz​ supply, and the source is rated for 100,000 hours. On LAMBD equipment — T6 Mini 5–20 W, LM-11-3 20–30 W, LM-1-x MOPA 20–100 W and LM-9-2 50–100 W​ — this delivers ±0.001 mm repeatability, a 0.01 mm minimum line width​ and galvo speed up to 7000 mm/s. For an English-site reader the key idea is simple: 1064 nm is not “stronger,” it is better matched to metal, and that match is why fiber is the best-selling laser class in the world.

A 1064 nm mark is produced by three distinct physical mechanisms, and knowing the difference is what separates a clean code from a failed one. First, oxidation (annealing).​ At moderate energy density the surface is heated to the temperature where an oxide film forms, but does not melt; no metal is removed, and the color comes from oxide thickness. This is how dark and colored codes are made on stainless steel and titanium without material removal​ — the required method for medical instruments and thickness-critical parts. Second, melting and swelling.​ At higher energy the surface melts locally and, on cooling, forms a micro-relief that scatters light, so the code appears bright and matte. Third, ablation.​ At high energy density the material vaporizes and is ejected, leaving a deep track — deep engraving, which the LM-9-2 50–100 W​ performs up to 1.0 mm​ in steel and titanium. The switch between modes is set by three parameters: power percentage, pulse repetition rate (20–4000 kHz) and scan speed (300–8000 mm/s), while pass count sets the depth. LAMBD builds recipes so that each job uses the least aggressive mode that works: oxide for a serial number, melting for a readable logo, ablation for a stamp or deep engraving.

Stainless steel is the most rewarding material for a fiber laser because it holds a stable, corrosion-resistant and readable code. The baseline recipe for a dark anneal on an LM-11-3 30 W​ is 40–70% power, 20–50 kHz, 300–800 mm/s, 1–2 passes. On the LM-1-5 MOPA 20–30 W, the same result comes at lower average power thanks to a short pulse, which reduces the heat load on the part. A white mark​ on stainless is made either by melting at 60–90% power, 20–30 kHz, 200–500 mm/s, or by multiple low-energy passes that build a matte relief without darkening. Color marking​ is a separate discipline: oxide thickness can only be controlled in nanometers by a MOPA source with adjustable pulse width <10 ns–~200 ns, and on steel this yields stable hues from straw to blue. Grade matters. AISI 304​ holds color and black anneal predictably; AISI 316​ needs slightly more energy because of its molybdenum; AISI 430 (ferritic)​ may give a duller contrast. Always test on an offcut of the same sheet, because mill finish, Scotch-Brite brushing, mirror polish and passivation all change absorption. For medical and food equipment, LAMBD recommends the oxide mode with no material removal, plus a mandatory ISO/IEC 15415​ check after reading.

Aluminum is the hardest of the three base metals because it reflects up to 90%​ of 1064 nm radiation and instantly grows its own oxide film. On bare 6061 or 1050 aluminum​ the starting recipe is 30–60% power, 20–40 kHz, 400–900 mm/s, 1–2 passes; the mark comes out light because the laser creates a micro-relief in the oxide rather than changing the metal color. For a dark, high-contrast code, use a multi-pass regime with lower energy per pass — the surface darkens without deep removal. Anodized aluminum​ behaves differently: the laser burns the dye out of the anodic layer and exposes the light substrate, so a white mark needs only 20–50% power, 30–80 kHz, 500–1200 mm/s, 1 pass. Color marking on anodized aluminum is where LM-1-x MOPA​ excels: vary pulse width and frequency and you get a palette from black to gold, green and blue — with no paint or lacquer. Two rules are mandatory. First, never mark through a protective film or oil film: a melted film leaves a dirty edge and soot. Second, do not overheat thin walls: aluminum conducts heat away fast, but thin sections warp, so on electronics housings and heat sinks you lower power and raise speed. LAMBD recommends storing separate recipes for “6061_bare,” “6061_anod_black” and “6061_anod_white” — they must never be mixed.

Brass and pure copper are the most demanding metals for a fiber laser because they combine high reflectivity (up to 90% on copper) with high thermal conductivity: energy sinks into the bulk instead of staying in the spot. A conventional Q-switched source therefore leaves an unstable, blotchy mark on copper and can send hazardous reflections back into the optics. The answer is MOPA: a short pulse <10 ns​ deposits energy faster than copper can conduct it away, so the LM-1-x MOPA​ produces a clean, even code on brass and copper at 25–50% power, 40–120 kHz, 300–800 mm/s, 1–2 passes. Brass (CuZn30, CuZn37, CW614N / ЛС59-1) is easier than copper and already gives good contrast on a Q-switched source: 30–55% power, 20–60 kHz, 400–900 mm/s, 1 pass. The warning is heat — overheat the part and the zinc in the alloy vaporizes, darkening the edge of the code. For plumbing fittings, locks, decorative hardware and gifts, LAMBD recommends a single-pass surface-melt mode: the mark comes out bright, slightly relief and resistant to handling. On polished brass, always test a sample first — even 3–5%​ excess power produces burning and melt build-up. One practical note: copper and brass foul the head’s protective window faster with metal spatter, so inspect and replace the window more often than when marking steel.

A 1064 nm fiber laser​ behaves differently on steel, aluminum and brass not because the laser is temperamental, but because each metal has its own reflectivity, thermal conductivity and oxidation rate. Stainless steel​ gives a stable dark oxide mark at 40–70% power, 20–50 kHz, 300–800 mm/s; color and white marks require a MOPA source with pulse width <10 ns–~200 ns. Aluminum​ reflects up to 90% and is marked either on its oxide (30–60% power, 20–40 kHz) or on the anodic layer (20–50% power, 30–80 kHz), where MOPA delivers color without paint. Brass and copper​ need a short pulse and moderate power (25–50%), otherwise heat sinks into the part and zinc boils off the edge. The discipline is common to all three: a 30–50 µm spot, ±0.001 mm repeatability, 0.01 mm line width, <0.5 kW​ draw from 220 V/50 Hz, a 100,000-hour source, degreasing before marking, a HEPA + carbon extractor, and a 30-second sample​ before every batch. In the LAMBD line this means the T6 Mini 5–20 W​ for small batches, the LM-11-3 20–30 W​ for production, the LM-1-x MOPA 20–100 W​ for color and contrast, and the LM-9-2 50–100 W​ for automation — all sharing one EZCAD + JCZ​ platform and variable data imported from Excel via CSV. For an English-site audience the conclusion is direct: master the absorption physics of these three base metals and you can build a working recipe for any alloy, from titanium to precious metals.