How UV Laser Marking Works on Plastic
UV lasers operate at 355 nm — a wavelength that interacts with plastics through a fundamentally different mechanism called photochemical decomposition (often called “cold marking”):
The key difference: UV marking doesn’t rely on heat. The energy goes directly into chemical change rather than thermal absorption. This is why UV lasers can mark plastics that would melt, warp, or degrade under CO2 or fiber laser treatment.
UV Marking Results by Plastic Type
| Plastic | Mark Quality | Typical Result |
|---|---|---|
| ABS | Excellent | High-contrast dark mark; no melting or deformation |
| Polycarbonate | Excellent | Clean dark mark; no bubbling; maintains dimensional stability |
| Nylon | Excellent | Dark, high-contrast mark; no warping |
| PEEK | Good | Dark mark on light PEEK; slight surface modification |
| PE/PP | Fair | Lower contrast than CO2; may need additive-enhanced grades |
| PVC | Good | Clean mark but still produces chlorine gas — ventilation required |
| POM (Delrin) | Good | Dark contrast mark; minimal thermal impact |
UV Typical Settings for Plastic Marking
| Parameter | Range |
|---|---|
| Power | 3–10W (UV lasers are lower power but highly efficient) |
| Speed | 200–800 mm/s |
| Frequency | 20–80 kHz |
| Pulse Width | 1–20 ns |
| Passes | 1 (usually single pass is sufficient) |
Critical tip for UV on plastic: Focus is everything. UV lasers have a very small spot size (typically 10–20 µm), which means depth of field is tight. Even a 0.5mm focus error can significantly degrade mark quality. Always verify focus on a test piece before production runs.
When UV Is the Right Choice
- Medical device components (polycarbonate housings, ABS connectors) where dimensional accuracy can’t be compromised
- Electronic housings and connectors that require fine text, small QR codes, or micro-labels
- High-contrast marking on sensitive plastics where CO2 causes melting or bubbling
- Transparent or translucent plastics where you need a visible mark without structural damage
When David Kowalski’s medical device company switched from CO2 to UV marking on their polycarbonate IV connector housings, the defect rate from melting and warping dropped from 12% to under 0.5%. The UV system cost three times more, but it paid for itself in scrap reduction within four months.
