Laser Marking on Magnesium and Zinc Alloys 1

Magnesium and zinc alloys cannot simply be treated as “lightweight metal”: their physical behavior demands a completely different approach from steel. Magnesium (AZ31B, AZ91D, AM60, WE43)​ is specified wherever weight is counted in grams — automotive components, aerospace parts, electronics housings, power tools, and motorcycle or bicycle assemblies. Zinc and ZAMAK (Zamak 3, 5, 7, zinc die-cast, ZA-8/12/27)​ form the base of hardware, locks, handles, enclosures, awards and gift products. Both materials melt at lower temperatures than steel, both oxidize rapidly, and both are highly reflective — which is exactly why a fiber laser creates a mark almost instantly, but also why an inexperienced operator can burn through, pit or warp the part. The correct choice is a 1064 nm fiber laser: it forms a stable oxide layer (dark on magnesium, light to grey on zinc) without removing metal, so the code is permanent, corrosion-resistant and readable. 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​ — the beam focuses to a 30–50 µm spot, delivers ±0.001 mm repeatability​ and a 0.01 mm minimum line width. For an English-site reader the point must be stated plainly: magnesium and zinc are “fast-oxidizing, low-melting alloys that need a cool, precisely dosed recipe,” not “aluminum under a different name.”

Magnesium marks more easily than zinc, but only if two conditions are met — a low temperature in the spot and a short interaction time. The recommended starting window on an LM-11-3 30 W​ is 30–50% power, 40–100 kHz, 300–800 mm/s, 1–2 passes; on a 20 W T6 Mini or LM-1-5, it is better to move to the upper part of the speed range and limit the job to one pass, because lower power requires a faster scan to avoid local overheating. The objective is a thin, uniform oxide film — not a crater. AZ31B and AZ91D, the two most common cast and wrought grades, accept this window well and produce a dark, high-contrast code: a serial, QR or logo. WE43 and other rare-earth grades​ oxidize even more actively, so they often need 5–10% less power. Code quality is determined less by the grade than by surface condition: polished magnesium marks darker and more evenly; cast or shot-blasted surfaces give a grainy trace; and parts carrying oil, cutting fluid or a conversion coating must be degreased first — otherwise the code will be blotchy and moisture may remain under the film. In a production recipe, deep engraving must never be used: removing metal exposes fresh, unprotected magnesium and creates a corrosion site. Use annealing-type marking (oxide only), keep to 1–2 passes, and before starting a batch, make a 30-second sample​ on the actual part.

Zinc alloys behave differently: zinc oxide is lighter in color, while the metal itself is soft and low-melting. On ZAMAK and zinc die-cast, an ordinary Q-switched marker gives a usable grey code, but the result is often uneven — at low power it looks “washed out,” at high power “burnt.” This is where MOPA pulse-width control​ justifies itself: the LM-1-x MOPA​ family (LM-1-5 20–30 W, LM-1-6 50 W) lets you vary pulse width from <10 ns to ~200 ns​ at up to 4000 kHz, so you tune the thermal dose rather than merely moving the power slider. A good starting point for a clean, high-contrast zinc mark is 25–45% power, 60–150 kHz, 400–1000 mm/s, 1 pass; for polished or chrome-plated surfaces, shorter pulses and higher frequency are preferred. On satin or ground zinc, frequency is better reduced to 40–80 kHz​ and speed slightly lowered to build contrast without pitting. Galvanized steel​ is a separate case: the coating is thin, so excess energy burns through to the steel and creates a two-tone mark at the boundary. Keep power at the low end, use one pass, and always test on a real galvanized panel. Lead-free and decorative zinc parts​ — locks, handles, badges, enclosures — are marked by the same principle as magnesium: oxide only, no aggressive post-cleaning, and never mark through an oil film. LAMBD recommends keeping two recipes per alloy family — “ZAMAK_dark_1.0mm” and “ZAMAK_light_0.5mm” — and selecting not by guesswork but by the part’s finish.

For magnesium and zinc, the right machine is almost always air-cooled fiber: compact, energy-efficient, low-maintenance, and free of the chiller complexity required by 355 nm UV. For prototypes, jewelry, keys, gifts and small batches, choose the T6 Mini 5–20 W​ — it draws <0.5 kW​ from a 220 V/50 Hz​ supply, fits a 6–8 m²​ workshop and carries a 100,000-hour source. For serial die-cast housings, hardware and serialized marking, choose the LM-11-3 20–30 W​ with a 110×100 mm field​ (optional to 300×300 mm), galvo speed to 7000 mm/s​ and the same EZCAD + JCZ​ workflow. For color, white marks and high contrast on coated or anodized surfaces, add an LM-1-x MOPA; for high-throughput 24/7 lines, move to the enclosed LM-9-2 50–100 W​ cell with interlock and optional IP54/IP65. Two requirements are non-negotiable. First, the fume extractor.​ Magnesium and zinc fumes are fine and irritating; they must be captured at the source with a HEPA + activated-carbon filter. LAMBD treats this as mandatory, not optional, because smoke on the F-theta lens changes the focus and destroys repeatability. Second, surface preparation.​ Degrease with isopropyl alcohol, remove cutting fluid and let the part dry; never mark through oil, paint, powder coat or a thick conversion layer unless the recipe has been validated specifically for that coating. The LM-8-1 CCD​ camera locates a randomly loaded Mg/Zn part and corrects its position, while the LM-9-2​ cell can verify the code immediately after marking — reducing scrap on mixed lines where part orientation changes constantly.

A good-looking mark is not yet a finished result: on magnesium and zinc, the mark must survive handling, washing, salt spray, and — for magnesium — its own corrosion-protection system. LAMBD recommends a four-step validation. Step 1 — contrast and geometry.​ After marking, check the code to ISO/IEC 15415​ (2D) or ISO/IEC 15416​ (linear): modules must be even, with no burns, bridges or missing cells. Step 2 — first-read rate.​ Scan the code with several readers at different distances and angles, and record the result in the technical file. Step 3 — environmental testing.​ For parts used outdoors or in marine conditions, run a salt-spray or humidity cycle and re-scan; the oxide mark on magnesium and zinc usually holds up well, but a burnt or pitted code fails first. Step 4 — database linkage.​ Every code must be tied to a record. LAMBD imports serial numbers, dates, lot numbers and expiry from Excel via CSV​ into EZCAD, then exports the log to MES/ERP. Two rules protect the part. Never use deep engraving in a serial recipe for Mg/Zn​ — only the oxide preserves the protective layer. Never wash a marked part with aggressive solvents or abrasive blasting, because both methods remove the very oxide that makes the code readable. For an English-site reader the practical conclusion is clear: magnesium and zinc are excellent candidates for permanent laser marking, but only when the recipe is built around a thin, controlled oxide layer, the lens is kept clean, fumes are extracted, and every code is verified and logged.

Laser marking on magnesium and zinc alloys​ is performed best with a 1064 nm fiber laser​ in a cold-oxidizing mode, not by deep engraving. Magnesium (AZ31B, AZ91D, WE43, AM60)​ produces a dark, stable mark at 30–50% power, 40–100 kHz, 300–800 mm/s, 1–2 passes; zinc and ZAMAK​ require a gentler regime and benefit from MOPA pulse-width control — 25–45% power, 60–150 kHz, 400–1000 mm/s, 1 pass, with polished surfaces favoring shorter pulses and higher frequency. On LAMBD equipment this means a 30–50 µm spot, ±0.001 mm repeatability and 0.01 mm line width, enough to place a code even on a thin-wall part. The production discipline is the same for both metals: degrease first, mark oxide only, keep to 1–2 passes, remove fumes with a HEPA + carbon filter, protect the lens, validate to ISO/IEC 15415, and log every serial number through CSV​ into MES/ERP. Machine choice follows volume — T6 Mini 5–20 W​ for small batches, LM-11-3 20–30 W​ for production, LM-1-x MOPA 20–100 W​ for contrast and color, LM-9-2 50–100 W​ for automated cells — and every model shares EZCAD + JCZ, files and recipes. For an English-site audience, the conclusion is unambiguous: treat magnesium and zinc as fast-oxidizing, low-melting alloys that reward a gentle recipe, and they will deliver a permanent, corrosion-resistant, high-contrast code without the pitting, warping or coating damage that comes from treating them like steel.