Laser marking and engraving
Marking and engraving are synonyms, the same operation: in both cases, the laser burns a rasterised or vectorised image (photos, lines, letters) in the surface of the material. Both metal and non-metal material marking is possible.
The applications of laser marking:
- product marking – serial numbers, logos, symbols
- promotional items – engraving of pens, pencils, keychains, mobile phone charms
- denim distressing and engraving
- anodised aluminium marking – selective removal of the anodised surface
- stamp making
- tags and plates engraving – metal signs, wood plates, plastic nametags
- plastic cards marking – logos, names, numbers, EAN codes
The advantages of laser marking:
- high precision(in µm)
- lightfast, waterproof and abrasion resistant marking (compare to printing)
- greyscale marking possible
- variable depth (from light marking to stamp making)
- very thin lines or small dots possible
- minimal heat load
- no dust, almost no noise
- easy production line integration
- “on-the-fly” marking possible
Almost all metals are suitable for laser marking.
- gold, silver, platinum
Lasers for metal marking:
Nd:YVO4 fiber laser – with its high life expectancy and low maintenance, the Nd:YVO4 fiber laser, with power from 5 to 200 W, is a very popular solution for metal marking. The 1064 nm wavelength provides thin, precise lines and dots. Fiber lasers can be fitted with a guiding pilot laser for exact positioning and preview. The high acquisition cost is compensated for by the efficiency (50 %), small size, simple air cooling and easy installation and integration.
Nd:YAG – older, but still popular. In comparison to Nd:YVO4 lasers, the Nd:YAG lasers need more maintenance (optical parts replacement, resonator and pilot laser resetting, lamp replacement) and a water cooler is often necessary, even for low power systems. Cheaper systems often suffer from a low quality, less precise beam. The main advantage of Nd:YAG lasers is high pulse energy in Q-switched systems.
CO2 laser – not the first choice for metal materials. Needs a much more higher power in comparison with shorter wavelength lasers.
The best systems for marking are:
- galvo lasers – extremely fast and precise, low-maintenance, with high life expectancy. The laser beam is deflected by rotatable, dynamic mirrors and therefore is not always strictly perpendicular to the working surface. Thus, galvo lasers are not recommended for deep engraving, eg. stamp making. The speed and flexibility makes the galvo lasers perfect for production lines.
- laser plotters (flatbed lasers) – the beam is applied vertically, at a right angle. Plotters are suitable for a wide range of applications, including marking, engraving and cutting, can have a very large working area and are perfect as standalone machines.
Anodized aluminium marking:
- paper, cardboard
- perspex / plexiglass / acrylic glass
- wood, plywood
- leather, leatherette, denim, felt
- PVC (fume extraction and filtering necessary)
Lasers for non-metal marking:
CO2 laser – for marking, 30W to 150W laser sources are typically used. (150W and more is also suitable for cutting). CO2 laser have a high life expectancy (10000-20000 hours) and simple maintenance requirements (check-up and cleaning once or twice a year).
DPSS laser – with wavelength 532 nm (green laser), suitable for high contrast marking of PVC and other plastic materials. Low power (up to 10 W) laser with a very thin beam (20 times thinner than CO2 laser).
Wood cutting and marking with a 100W CO2 laser:
Leather marking and cutting test on thick vegetable tanned leather: