Laser Etching
Key Takeaways
- Etching affects only the upper surface layers, typically a few microns deep.
- It sits between marking and engraving — deeper than a colour change, shallower than material removal.
- Laser choice follows the material: CO2 for polymers, fiber for metals and plastics, UV for high resolution.
- Fume extraction is required, since surface melting and vaporisation release byproducts.
Laser Etching
Laser etching is a shallow surface process that melts and slightly displaces the top layer of a polymer, altering its texture and reflectivity to create a visible mark, typically to a depth under 0.025 mm. It sits between surface marking, which removes nothing, and engraving, which cuts a measurable recess.
The contrast in an etched mark comes largely from a change in surface finish rather than a change in colour. A glossy moulded surface, locally melted and resolidified, scatters light diffusely and reads as a lighter, matte or frosted area against the surrounding gloss. On transparent polymers the same effect produces a translucent, frosted appearance.
How It Differs in Practice
| Etching | Engraving | |
|---|---|---|
| Depth | Under ~0.025 mm | 0.05–0.5 mm and beyond |
| Dominant mechanism | Surface melting and micro-displacement | Vaporisation and removal |
| Speed | Fast — usually a single pass | Slow — multiple passes |
| Heat input | Low | High |
| Abrasion resistance | Moderate | High |
Where It Suits Plastics
- Transparent and clear polymers — acrylic, polycarbonate and clear PET, where a frosted mark is legible without any colourant or additive. This is the classic application.
- Anti-glare and tactile surface features, where a matte region is functional rather than decorative.
- Decorative and branding work on gloss-moulded consumer parts.
- Heat-sensitive components where the low energy input of a single shallow pass avoids the distortion that engraving would cause.
Its limitation follows directly from its shallowness: an etched mark can be polished, abraded or worn away more readily than an engraved one. For parts facing sustained abrasion, chemical attack or aggressive cleaning cycles, engraving or an additive-driven carbonized mark will outlast it.
Getting a Clean Etch
Because the process operates in a narrow band just above the melt threshold, it is more parameter-sensitive than either marking or engraving. Slightly too much energy tips it into engraving with the associated burr and haze; slightly too little produces an inconsistent, patchy mark. Practical guidance:
- Start with low power and high marking speed, then reduce speed incrementally rather than raising power.
- Use a high repetition rate so that pulses overlap and produce a uniform matte field rather than discrete pits.
- On transparent parts, confirm that the beam is focused at the intended surface — it is easy to focus through the material onto the far face.
- Watch for stress crazing on polycarbonate and acrylic, which can appear hours after processing rather than immediately.
For heat-sensitive and optically demanding work, a UV vanadate laser produces a finer, cleaner etched appearance than an infrared source because the interaction is largely photochemical — see cold laser marking.
Related Terms and Reading
- Laser marking clear and transparent plastics
- Acrylic laser marking
- Laser engraving
- Plastics laser marking solutions
Applying this in production
The Sabreen Group provides independent engineering support for laser etching parameter development for transparent and gloss-moulded plastics. If you are specifying a process, qualifying a material or troubleshooting a production problem, our engineering services team can help. Contact us to discuss your application.
Frequently Asked Questions
What is laser etching?
A marking technique that creates shallow, visible marks by controlled melting and vaporisation of the surface. It is non-contact and precise, typically producing marks a few microns deep for permanent text, logos and codes.
How is etching different from laser engraving?
Depth and material removal. Engraving removes material more deeply to create recessed features, while etching only affects the upper surface layers. Laser marking is shallower still, often producing a colour change or surface reaction with no material removal at all.
Which laser type suits which material?
CO2 at 10.6 μm for polymers, wood, glass and some ceramics, which absorb it strongly. Fiber at 1.06 μm for metals and plastics, offering high precision. UV at 355 nm where high resolution and minimal thermal impact are needed.
What parameters control etching quality?
Laser power controls the degree of surface melting and mark visibility. Pulse duration affects thermal damage and detail, with shorter pulses cleaner. Scan speed trades heat buildup against contrast. Focus position determines energy concentration at the surface.
What material properties affect the result?
Melting point, absorption at the laser wavelength, and thermal conductivity. Heat management matters to avoid distortion or discoloration, and adequate ventilation and fume extraction are needed to handle the byproducts generated.
