Laser Annealing

When a laser beam is held over a carbon-containing metal for a controlled time, the heat drives oxygen from the surrounding air into the top few hundred nanometres of the metal, growing a thin transparent oxide layer in place.

That skin sits on top of the original surface, so the part keeps its dimensions and structural strength — nothing is cut away. This is what makes annealing the marking method of choice wherever a mark has to survive without weakening the part underneath it, most notably on surgical instruments and implants.

A laser annealing marking beam heats the base metal — titanium, steel, stainless steel, or iron — and a thin oxide layer grows on top of it as it cools. The colour you see is determined entirely by how thick that oxide layer grows.

The colour comes from light bouncing off two surfaces at once — the top of the new oxide layer and the metal underneath it As the oxide layer grows thicker with more heat, the surface goes light golden to a flat grey-black as the layer gets thick enough to scatter light instead of filtering it.

Beam sets the exposure time Laser power, spot size, and scan speed decide how long each point on the surface stays hot enough to oxidise.

Oxide layer forms Oxygen from the air combines with the surface, building an oxide film only tens to a few hundred nanometres thick.

Light interferes Reflections from the top and bottom of that film cancel some wavelengths and reinforce others the film thickness picks the colour.

Colour reads as the mark The result is a smooth, wear-resistant, permanent mark with no groove and no material lost.

Laser engraving and laser etching both remove material to create a visible mark whereas annealing removes nothing. Engraving cuts a groove; etching melts a shallow surface texture; annealing only grows a thin, colour-shifting oxide layer on top of the original surface. Which is why annealing is the only process that leaves the part's dimensions, weight, and structural strength completely unchanged and does not change its functionality.

Markolaser designs and builds its marking machines including the LEO, Orion, Ursa, and Hercules ranges and UV lasers for the fine power control that annealing depends on.

Sample before you commit Send a part and get it annealed as a sample so the exact colour and finish can be checked before ordering a machine.

Pan-India service network Application and service support out of Gurugram, Haryana, Delhi NCR, Baddi, Telangana, Tamilnadu, Karnataka, Punjab, Gujarat, Coimbatore, Faridabad, Noida, Pune, Mumbai, Bengaluru and other manufacturing hubs of India.

Traceability built in Machines integrate with ERP/MES systems, so an annealed code can feed straight into a traceability record on the production line.