Buyers often send us a parts list and ask one question about fiber vs CO2 vs UV laser marking: “Which one do I buy?”
The answer is almost never about watts. It is about what your parts are made of. Each laser makes light at a different wavelength.
Each material soaks up some wavelengths and lets others bounce off or pass through. Match the two, and you get a clean, fast mark. Get it wrong, and no amount of power will fix it.
Here is the short version. Metal parts: fiber. Wood, paper, cartons, leather, PET and most glass: CO2. White or light plastics, fine codes and heat-sensitive parts: UV. The rest of this guide shows why, with real samples from the HeatSign lab, costs, common mistakes and a material-by-material table.
Why Does the Material Decide Which Laser You Need?
A laser can only mark what it is absorbed by. Metals absorb fiber light (1,064 nm) far better than CO2 light (10.6 µm). Wood, paper, glass and most plastics absorb CO2 light very well. UV light (355 nm) is absorbed by almost everything, and its small spot gives the finest detail.
Think of it like sunlight on a black car and a white car. The black car gets hot because it soaks up the light.
The white car stays cool because it reflects it. Laser marking works the same way, only the “color” that matters is the laser’s wavelength.
Metal and fiber. Polished metal reflects most CO2 light. At room temperature, metals absorb roughly three times more light at 1 µm than at 10.6 µm, and for steel the gap can be larger. That is why a fiber laser marks steel in seconds, while a CO2 laser leaves bare steel almost untouched.
Non-metals and CO2. Wood, paper, leather, glass and most plastics soak up 10.6 µm light in a very thin top layer. The mark is fast and clean. It is the same reason CO2 lasers use special zinc selenide lenses instead of glass: ordinary glass would absorb the beam.
Clear and white materials and fiber. Fiber light passes straight through clear glass and clear plastic. White plastics reflect most of it. So a fiber laser leaves a weak mark, or none, unless the plastic is dark or contains a laser additive.
UV and small detail. A focused spot gets smaller as the wavelength gets shorter. With the same 160 mm lens, the theoretical spot is about 12 µm for UV, 40 µm for fiber and 260 µm for CO2.
Real lines are 1–3 times wider than the spot, but the order stays the same. That is why UV is the pick for tiny codes and micro text.
Five words you will see
- Wavelength
- The “color” of the laser light, in nanometers (nm) or micrometers (µm). 1 µm = 1,000 nm.
- Annealing
- Heating metal just under its surface so it turns dark, with no material removed. Common on stainless steel.
- Engraving
- Removing material to make a mark with depth. Lasts through wear and blasting.
- MOPA fiber
- A fiber laser whose pulse length can be changed. It widens what one fiber machine can do.
- Flying marking
- Marking parts while they move on a line, without stopping it.
Which Laser Should You Use for Each Material?
Use fiber for bare and coated metals and dark plastics. Use CO2 for wood, paper, cartons, leather, acrylic, PET and decorative glass. Use UV for white and light plastics, fine codes on glass, ceramics and electronics. When a cell says “test first,” the result depends on the grade and color of your material.
First choiceWorksTest firstNot suitable
Material | Fiber 1,064 nm | CO2 10.6 µm | UV 355 nm | What to know |
|---|---|---|---|---|
Stainless and carbon steel | First choice | Not suitable | Works | Fiber engraves deep or makes a black anneal mark. CO2 needs a marking spray on every part. |
Bare aluminum | First choice | Not suitable | Test first | Gray to white mark. Contrast is lower than on steel, so check code readability. |
Anodized aluminum | First choice | Works | Works | Bright white mark on dyed parts. A black mark needs a MOPA fiber. |
Brass and copper | First choice | Not suitable | Works | Fiber for depth and speed. UV gives fine, shallow surface marks. |
Painted or powder-coated metal | First choice | Works | Works | The laser removes the coating and shows the metal below. |
Dark plastics (ABS, PC, PA, PBT) | First choice | Test first | Works | Fiber gives a light mark. Too much power makes bubbles or burns. |
White and light plastics | Test first | Test first | First choice | UV turns the pigment dark. Fiber may leave little or no mark unless the plastic has a laser additive. |
Clear acrylic (PMMA) | Not suitable | First choice | Works | CO2 gives a frosted engraving. Fiber light passes straight through. |
PET bottles and film | Not suitable | First choice | Works | CO2 foams the surface into a white code. A 9.3 µm CO2 gives a whiter mark than 10.6 µm. |
PVC (cables, pipes, cards) | Works | Works | First choice | UV on white PVC, fiber on dark PVC. PVC fumes contain hydrogen chloride, so use fume extraction. |
Silicone and rubber | Test first | Works | Works | Soft surfaces. Check the mark after bending or stretching. |
Glass | Not suitable | Works | First choice | CO2 makes a fast frosted mark with tiny chips at the edges. UV makes finer text with less chipping. |
Glazed ceramics | Test first | Works | First choice | UV marks logos on mugs and tiles without cracking the glaze. |
Wood and plywood | Not suitable | First choice | Test first | Fiber light sinks into wood and heats it from inside. It leaves weak marks or scorches. |
Paper, labels and cartons | Not suitable | First choice | Works | CO2 burns away printed ink. Plan a dark “code window” on the box for good contrast. |
Leather | Test first | First choice | Works | CO2 gives a clean, darker engraving on natural leather. |
Electronics and PCBs | Works | Test first | First choice | UV marks small codes on chips, solder mask and housings with little heat. |
Based on HeatSign sample tests and published process guides. Plastics vary a lot by grade, color and additives, so always mark a real part before you buy.
The photo above shows two similar white plastic housings. Both codes scan. Look closely, though: the UV mark is darker, with sharper edges and no yellow halo.
On other white plastics, such as some POM and PP grades, a fiber laser leaves almost nothing at all. Users on laser forums report exactly this: a 30 W fiber that “did nothing” on white POM.
Glass shows the CO2 vs UV trade-off. CO2 makes a frosted mark quickly, and it looks fine on a tumbler or bottle. Under a loupe you see tiny chips along the edges, because the surface heats and cracks.
For small text, codes, or glass that must stay strong, UV is the safer choice. For more detail, read our guide to CO2 vs UV laser on glass and ceramics.
What Is Each Laser Good At?
Fiber is the everyday tool for metal: fast, sharp and almost maintenance-free. CO2 is the low-cost workhorse for non-metals and packaging lines. UV is the specialist for light plastics, glass and tiny detail, where heat or contrast is the problem.
Fiber Laser Marking: The Metal Specialist
A fiber laser makes light at about 1,064 nm inside a glass fiber doped with ytterbium. The beam is fine, strong and steady. Metals absorb it well, so it marks steel, stainless steel, aluminum, brass and titanium directly, with no coating.
It can make three kinds of marks. A deep engraving survives blasting and paint. A black anneal mark sits under the surface of stainless steel, so it keeps the rust protection.
A light etch is the fastest, for logos and codes. See laser etching vs engraving for depths.
Most serials, VINs and Data Matrix codes on metal parts are made with fiber lasers. A 20–30 W machine covers surface marks.
A 50 W or higher machine digs deeper. Our 20 W vs 30 W vs 50 W guide explains the trade-off.
CO2 Laser Marking: The Non-Metal Workhorse
A CO2 laser makes light at 10.6 µm from a sealed gas tube. Industrial marking machines use an RF metal tube, not the glass tube found in hobby engravers. The HeatSign HS-CL series tube is rated for over 20,000 hours and is air-cooled.
CO2 is fast on anything organic or glassy: wood, paper, cardboard, leather, acrylic, rubber, PET and glass. That makes it the standard on packaging lines, where a flying CO2 laser prints dates and lot codes on moving cartons and bottles, with no ink to buy.
The limit is metal. CO2 can remove paint, powder coat or anodizing from metal, but it cannot mark bare steel or aluminum. To do that, you must spray a marking compound on every part.
UV Laser Marking: Fine Detail With Little Heat
A UV laser starts as an infrared laser, then uses crystals to turn the light into 355 nm. Each UV photon carries more energy, so it can break chemical bonds in plastic directly. The heat-affected zone is much smaller than with fiber or CO2.
You may see UV called “cold marking.” It is not truly cold, as some heat is still involved. But the mark stays crisp, and thin films, white plastics and glass do not melt, bubble or crack as easily.
UV is the go-to for white and light plastics, medical and cosmetic packaging, cable jackets, glass, ceramics and electronics. For a deeper look, read our UV laser marking guide or UV laser vs fiber laser.
Fiber
How the mark forms
Heats metal to change its color, or removes a thin layer. On dark plastic, it lightens or foams the surface.
CO2
How the mark forms
Burns or removes the top layer of wood, paper, ink and coatings. It foams PET white and frosts glass.
UV
How the mark forms
Changes the color of pigments just under a plastic surface, or removes a very thin layer with little heat.
How Do Fiber, CO2 and UV Compare on Cost, Speed and Upkeep?
Fiber has the lowest running cost and almost no upkeep. CO2 machines are low-cost and air-cooled, with a gas tube that is refilled after tens of thousands of hours. UV costs a little more, uses the least power, and needs more care: crystals wear, and the 10 W models need a water chiller.
Fiber | CO2 | UV | |
|---|---|---|---|
Wavelength | 1,064 nm | 10.6 µm (some 9.3 µm) | 355 nm |
Typical marking power | 20–100 W | 30–60 W | 3–10 W |
Theoretical spot, 160 mm lens | About 40 µm | About 260 µm | About 12 µm |
Electricity to laser light | About 20–30% | About 10–15% | About 10% or less |
Laser source life | Pump diodes projected at 100,000 hours | RF tubes 20,000–45,000 hours, then a gas refill | Tens of thousands of hours; crystals and diodes wear |
Cooling | Air | Air (water optional) | Air on 5 W, water chiller on 10 W |
Things you keep buying | Fume filters only | Fume filters; tube refill after years | Fume filters; chiller water; crystal service |
HeatSign price range | $1,950–$5,000 desktop; $4,000–$7,000 flying | $2,900–$5,900; flying from $3,800 | $3,000–$5,900 desktop; more for over 10 W, flying or custom builds |
Spot sizes are theoretical, for a typical beam and a 160 mm lens. Efficiency and lifetime figures are laser-source makers’ ratings, not guarantees.
On a marking machine, the power bill is small for all three. A 50 W fiber laser draws a few hundred watts in total.
The real cost differences are upkeep, scrap and downtime. So pick the laser that marks your material right the first time, then compare prices.
Three claims to read carefully
- “Fiber lasers are over 50% efficient.” That figure comes from kilowatt cutting lasers. Pulsed marking sources are rated at about 20–30%.
- “A fiber laser lasts 100,000 hours.” That is the makers’ projected life of the pump diodes. It is a design figure, not a machine warranty.
- “UV marking is completely cold.” UV has a much smaller heat zone, not zero heat. Thin or sensitive parts still need the right settings.
Can a MOPA Fiber Laser Replace a UV Laser?
Sometimes. A MOPA fiber lets you change the pulse length, from a few nanoseconds to several hundred. That makes black marks on anodized aluminum, black and color marks on stainless steel, and gentler marks on many plastics. For dark marks on white plastic, clear materials or glass, you still need UV.
MOPA fiber is enough when
- Most of your parts are metal
- You need black marks on anodized aluminum
- You need black or color marks on stainless steel
- Some plastic parts are dark or colored
You still need UV when
- You need dark codes on white or light plastic
- You mark glass, clear film or clear plastic
- Codes are very small, under a few millimeters
- The part cannot take heat, like thin medical film
One lesson we see often: buying more fiber watts does not make a black mark on stainless steel. A forum user with a 100 W standard fiber could not get a steady black. A 60 W MOPA made it on a cheap knife.
The pulse control matters more than the power. See the HeatSign MOPA fiber laser and our MOPA vs Q-switched guide.
Which Setup Fits Your Production Volume?
The material picks the laser type. Your volume picks the setup. Small batches run on a desktop marker. Daily production adds a safety enclosure, a rotary axis or fixtures. Continuous lines use flying lasers that mark parts as they move.
Batch
A few to a few hundred parts a day
Setup: desktop fiber, CO2 or UV marker.
Focus: clean marks and quick file changes.
Most factories
Daily
Steady shifts, many part types
Setup: enclosed Class 1 station, rotary axis for round parts, fixtures.
Focus: cycle time and operator safety.
Inline
Parts never stop moving
Setup: flying fiber (up to 12,000 mm/s) or flying CO2 on the conveyor.
Focus: line speed, encoder sync, uptime.
Work out the seconds you have per part. Then pick a power that finishes the mark inside that time, with room to spare. Too little power slows the line.
Far too much adds cost you do not need. If you are not sure, send us a part and your target speed. HeatSign will test it and tell you the power and setup that fit.
Do You Need One Laser or Two?
If over 80% of your parts are one material family, buy one laser for that family. If you mark metal parts and also cartons, wood or white plastic housings, plan for two: fiber plus CO2, or MOPA fiber plus UV. No single machine can switch wavelengths.
Many shops learn this the hard way. They buy one machine to “do everything,” then add a second within a year. Users on laser forums who own both a fiber and a CO2 say they still use each one every week, for different jobs.
Your parts | Good pair | Why |
|---|---|---|
Metal parts + cartons or wood crates | FiberCO2 | Each laser stays in its comfort zone. Both are low-cost. |
Metal parts + white plastic housings | MOPAUV | MOPA covers metals and dark plastics. UV covers light plastics and small codes. |
Bottles, film and labels only | CO2 or UV | CO2 for PET and paper. UV for thin film and fine codes. |
Cables of many colors | FiberUV | Fiber for dark jackets, UV for white ones. See our laser wire marker guide. |
Before you buy, send us these 6 things
- The material, grade and color of each part.
- Two or three real sample parts.
- What you mark: text, logo, barcode or Data Matrix, and its size.
- How it must read: by eye, by scanner, or to a code grade.
- Parts per hour, or line speed.
- What happens after marking: painting, blasting, passivation or washing.
What Mistakes Do Buyers Make When Choosing a Marking Laser?
The common mistakes are buying CO2 for bare metal, fiber for white plastic, more fiber watts for black stainless steel, and CO2 for small codes on glass. Ignoring fumes and code contrast causes the rest. A real sample test before purchase avoids all of them.
1. CO2 for stainless steel parts
CO2 light bounces off bare metal. The only way is to spray a marking compound on every part, and the mark can rub off if the settings are wrong. For metal parts, choose fiber.
2. Fiber for white plastic
White pigment reflects 1,064 nm light. The mark comes out faint, or not at all. Test first, or choose UV.
3. More watts for black stainless
A deep black anneal mark depends on pulse control, not power. A 100 W standard fiber can fail where a MOPA succeeds.
4. CO2 for small codes on glass
CO2 cracks glass into a frosted mark with chipped edges. That is fine for a logo. For small text and 2D codes, choose UV.
5. Light ink on cartons
CO2 makes contrast by burning away ink. On pale yellow or beige print, there is little to see. Ask your printer for a dark code window.
6. No fume plan for PVC
PVC releases hydrogen chloride when heated. It corrodes machines and harms workers. Add fume extraction from day one.
Is Laser Marking Safe? Eyes, Fumes and Enclosures
Yes, when the machine is set up correctly. An enclosed marking station with door interlocks is Class 1, so operators need no goggles. An open machine is Class 4 and needs wavelength-rated eyewear. All three lasers make fumes, so use a fume extractor, especially on plastics, PVC and coatings.
The laser inside almost every marking machine is Class 3B or 4. A full enclosure with interlocks makes the whole machine Class 1.
If you open the service door, it is Class 4 again. Read more in Class 1 vs Class 4 laser markers.
Eyewear must match the wavelength. Fiber goggles do not protect against UV, and UV goggles do not protect against fiber light.
Choose glasses rated for your laser, as explained in our OD4 vs OD6 guide. HeatSign UV machines ship with UV-rated goggles.
For fumes, use a HEPA filter for dust and a carbon filter for gases. University safety guides warn that heating PVC releases hydrogen chloride and other toxic gases. If you must mark PVC, use strong extraction, like our industrial fume extractor.
See Each Laser at Work
Where Does a Diode Laser Fit?
A diode laser is a low-power blue or infrared laser built for hobby engraving on wood and leather. It is slower, less precise and less durable than fiber, CO2 or UV for factory marking, and it cannot mark bare metal well.
Diode lasers are popular on desktop craft engravers because they are cheap. For production marking, they lack the power, speed and duty cycle you need. If you are weighing a diode against a CO2 for non-metals, see our CO2 vs diode laser comparison.
Which Laser Do Common Industries Use?
Automotive and machined parts use fiber. Food, drink and pharma packaging use CO2 for cartons and PET, and UV for white HDPE bottles and thin film. Electronics and medical devices use UV for small codes and fiber or MOPA for metal parts. Cable makers use fiber and UV.
Automotive and machined parts
Need: VINs, serials and Data Matrix codes that survive blasting, paint and years of use.
Laser: Fiber deep engraving or black anneal. See Data Matrix marking.
Food, drink and pharma packaging
Need: dates and lot codes at line speed, with no ink or solvent.
Laser: CO2 flying laser for cartons and PET; UV for white HDPE bottles and film.
Electronics and medical devices
Need: readable micro text and 2D codes with almost no heat damage.
Laser: UV for plastics and PCBs; MOPA for stainless instruments.
Wire and cable
Need: text on moving cable, in many jacket colors.
Laser: Fiber for dark jackets, UV for white and PTFE wire.
Which HeatSign Machine Fits Your Job?
For metal parts, start with a desktop fiber marker. For non-metals and packaging, a galvo CO2 marker. For light plastics, glass and fine codes, a 5 W or 10 W UV marker. All three run the same EZCAD software for text, serials, dates and 2D codes.
For metal parts: fiber laser marking machines20, 30 and 50 W desktop models from $1,950, a Class 1 enclosed model, rotary and flying versions. Air-cooled, no ink or gas.See fiber machines → 
For non-metals: CO2 laser marking machine40 or 60 W RF metal tube, rated over 20,000 hours, air-cooled. Galvo speed up to 7,000 mm/s. From $2,900.See the CO2 marker → 
For light plastics and glass: UV laser marking machine355 nm, 5 W air-cooled or 10 W water-cooled. Fine codes on plastic, glass and ceramics. Desktop models $3,000–$5,900; higher power, flying and custom builds cost more.See the UV marker →
Not sure which laser fits your parts?
Send us your part list or a few samples. HeatSign engineers will mark them on the right laser and send you photos or a video of the result, usually within one business day.
Fiber vs CO2 vs UV Laser Marking FAQ
Can one laser marking machine mark both metal and plastic?
A fiber laser marks metal and many dark plastics. It struggles with white, light and clear plastics. A UV laser marks most plastics and can mark metal, but more slowly. No machine can switch between fiber, CO2 and UV light, so mixed jobs often need two lasers.
Can a CO2 laser mark metal?
Not bare metal. A CO2 laser can remove paint, powder coat or anodizing from metal. To mark bare steel, you must spray a marking compound on each part first. For metal parts, a fiber laser is faster and needs no spray.
Can a fiber laser mark plastic, wood or glass?
Dark plastics, yes. White plastics, sometimes, and only weakly unless they contain a laser additive. Wood marks poorly and can scorch. Clear glass, no: the light passes straight through. Use CO2 for wood and UV for glass.
Is UV laser marking really cold?
Not completely. UV light breaks chemical bonds directly, so the heat zone is much smaller than with fiber or CO2. That is why it suits thin film, white plastics and glass. Some heat is still involved, so settings matter.
Which laser is better for white plastic, fiber or UV?
UV, in most cases. It turns the white pigment dark and gives sharp, high-contrast codes. Fiber can work on some white plastics, but the mark is often faint. Mark a real part with both before you decide.
Which laser needs the least maintenance?
Fiber. It is air-cooled, has no gas tube and needs only fume filters. An RF CO2 tube runs 20,000 to 45,000 hours before a gas refill. UV needs the most care: crystals wear, and 10 W models need a water chiller.
Does laser marking weaken stainless steel or cause rust?
For normal parts, no. A deep engraving can break the thin layer that stops rust. A black anneal mark avoids this, because it forms under the surface without removing metal. If your parts are passivated, plan where marking fits in the process.
Is laser marking safe to use?
Yes, with an enclosed Class 1 machine or the right eyewear on an open machine. Goggles must match the wavelength. Use a fume extractor with HEPA and carbon filters, especially for plastics, PVC and coated metals.
Can the software mark serial numbers and 2D codes?
Yes. The included software makes text, logos, barcodes, QR codes and Data Matrix codes. It counts serial numbers, adds dates and times, and can read data from a database or PLC for variable codes on a moving line.
Do I need a rotary axis?
Only for marks that wrap around rings, pipes, bottles or shafts. The rotary turns the part while the laser marks, so the text runs evenly around it. For a flat spot on one side, you do not need one.
Sources
- W. M. Steen, Laser Material Processing (metal absorptivity at 1.06 µm and 10.6 µm)
- Xie, Kar et al., “Temperature-dependent absorptivity and cutting capability of CO2, Nd:YAG and chemical oxygen-iodine lasers,” Journal of Laser Applications
- RP Photonics Encyclopedia, “CO2 lasers” and “Laser marking“
- Thorlabs, F-theta scan lens tutorial (focused spot size)
- IPG Photonics, nanosecond pulsed fiber laser data (wall-plug efficiency, pump diode lifetime)
- Laser Focus World, “Sealed CO2 lasers enter the high-power arena”
- J. Gabzdyl, “Application versatility of nanosecond pulsed fiber lasers,” Industrial Laser Solutions
- T. Lippert, “Laser Application of Polymers,” Advances in Polymer Science
- Novanta Photonics, “Alternative CO2 Laser Wavelengths” white paper (9.3 µm on PET)
- Carnegie Mellon University EHS, Laser Cutter Safety guideline (PVC fumes)
- IEC 60825-1, Safety of laser products
- HeatSign fiber, CO2 and UV laser marking machine specifications and sample tests
