Laser marking, engraving, cutting and welding could be applied to most of plastics, depends on the application, there is a wide spectrum range of laser types for plastic industry laser process: UV lasers, green lasers, fiber lasers as well as Co2 lasers for marking, Co2 lasers for cutting and diode laser for welding.
There are 4 technologies for plastic laser marking:
2: Color changing.
The plastic change color when laser light heats up the work piece surface locally, the exact color of marking depends on material type as well as laser additives in the plastic, the color change normally comes with chemical degradation and the material frothing process, the frothing laser could be seen and felt.
The color changing is either to get a white marking from black plastics or to get a black marking from white plastics, for a high contrast, readable making effect, good for most thermoset plastics.
Diode-pumped laser, Fiber laser at 1064nm wavelength, green laser at 532nm wavelength and UV laser at 355nm wavelength can be used for plastic color changing, green laser and UV laser is especially good to mark dark color against white plastics material.
A partial thermochemical process creating small gas bubbles with in the material when laser heat the work piece, forming a plastic foam layer. This makes the processed area appears brighter than the other parts of material.
Foaming normally used for dark thermosets plastic laser marking to get a high contrast bright marking effect, laser additive can be used to improve plastic absorption character.
Fiber laser at 1064nm is good for plastic foaming.
In laser engraving, short, powerful laser beam used to heat up the surface and subsequently vaporize the material, a visible depression up to 0.5mm created in the work piece, depends on the material's optical properties and the laser parameters.
There is often a chemical degradation at the engraving area, a color changing can be produced along with engraving.
Almost all plastic material could be engraved, thermoset plastics normally use fiber laser at 1064nm for engraving.
Instead of removal plastic material, laser ablation is used to partially remove the painted coating layer from the base materials and the base material become visible, the painted coating layer should have a different color with the base material.
A typical application of laser ablation is the back-lit keyboard and control elements in automotive industry for day/night design, expiry date laser coding on the lacquer layers of packaging material is another case of laser ablation.
Diode-pumped laser, Fiber laser at 1064nm, Co2 laser at 10640nm and green laser at 532nm is good solution for laser ablation.
UV laser opened a new avenue of laser marking, UV laser can give higher contrast marking effect for some of plastic and expedite the yield rate. Instead of heat up the work pieces, UV laser beam causes a photochemical reaction on the material surface, very low heat dissipation introduced and this is referred to as “cold marking” process.
The UV marking laser is good for thermal sensitive plastic products, leaving high contrast marking effect without damage on the thermal sensitive materials. The typical application of UV laser is silicon and glass.