GlossaryKind of term: Manufacturing termLaser marking
What is laser marking?
Laser marking applies text, a number or a code to a surface with a laser beam, without contact, mainly for identification and traceability.
No ink or stamp is involved, and besides text and numbers the mark can be a logo or a machine-readable code. The laser changes the surface locally: it discolours it, removes a thin layer or alters the colour of a coating. What has to go on the part comes from the drawing or the purchase terms: part number with revision, a serial or batch number, sometimes a Data Matrix code. Position, character height and font are often specified too.
What does laser marking depend on?
The effect depends on the material, any coating and the laser settings. On steel and stainless steel, annealing marking produces a dark oxide colour with no appreciable material removal; engraving does remove material and leaves a depth you can feel. On black anodised aluminium the laser bleaches or removes the dye in the oxide layer, leaving a light mark. Plastics discolour, carbonise or foam depending on their composition and additives. For a Data Matrix code marked directly on the part, contrast, cell size and the substrate decide whether it can be read reliably. Annealing marking puts heat into the surface and can lower the corrosion resistance of stainless steel locally.
How does laser marking work in practice?
A short text often takes the laser only seconds; deep engraving or a large area takes longer. Each piece adds handling: picking up, positioning, often in a dedicated nest, and unloading. A unique number or code per piece needs the data prepared per piece and the mark verified. The order relative to finishing matters: on black anodised aluminium you mark after anodising, and pickling or electropolishing can attack an annealing mark. For medical, food-contact or wet-environment applications the customer sometimes fixes the marking method or a post-treatment. When marking is subcontracted, transport and lead time come into play.
What is laser marking often confused with?
Laser marking is not laser cutting: marking changes only the surface, cutting goes through the material. Laser engraving is one form of laser marking in which material is deliberately removed; not every laser mark is an engraving. Engraving with a cutter on the machining centre is a different process: it costs spindle time but can be done in the same setup without extra handling.
Frequently asked questions
Should I mark before or after anodising?
For a light mark on black anodised aluminium, mark after anodising: the laser takes the colour out of the layer. Engraving before anodising is possible, but the engraving is dyed along with the rest and then shows little contrast.
How do I price laser marking?
Usually as handling per piece: pick up, position, mark, check and unload. If every piece carries a unique number or code, preparing that data counts as well. A dedicated nest is a one-off cost.
Does a laser mark harm stainless steel?
It can. The heat of annealing marking forms an oxide layer that can reduce corrosion resistance at that spot. How much depends on grade, settings and environment. For critical applications the customer often specifies the method or a post-treatment.