Marking is not cutting
A laser cutter is designed to go through the material. A laser marker is designed to change only the surface, or a very shallow layer of it, and leave the part intact. The beam is usually steered by a pair of small mirrors that move it very quickly across a limited field, rather than by moving a gantry over a large sheet. Power is typically lower, pulses are shorter and the aim is a clear, durable, repeatable mark. For the cutting side of the technology, see laser cutting machines.
Marking is common on tools, medical parts, electronics, automotive parts, packaging and many other products. The categories below are laser source types, not products; capabilities differ by manufacturer.
Common mark types
- Engraving. The laser removes material to form a recess. Deep engraving takes many passes and is slower, but the mark can survive wear, painting or light abrasion.
- Etching and ablation. A thin layer is vaporized, for example removing a coating or paint to reveal the material beneath. This is common for backlit buttons and labels.
- Annealing. The surface of some metals, such as stainless steel and titanium, is heated without removing material, producing an oxide layer that appears dark or colored. The surface stays smooth, which is a reason why annealing is often chosen for medical and food-related parts where crevices are undesirable. Acceptability for a particular application should be confirmed against the relevant requirements.
- Foaming and color change. Some plastics respond with a light or dark mark when heated by the beam.
- Surface texturing. Fine patterns can be created for grip or appearance.
1. Fiber laser markers
Fiber lasers are the usual choice for marking metals and also work on many engineering plastics. They tend to be reliable, compact and low maintenance, and they can engrave, anneal and ablate. They are the common general-purpose industrial marker. Some materials, such as clear plastics and glass, do not absorb their wavelength well.
2. CO2 laser markers
CO2 lasers have a longer wavelength that organic and non-metallic materials absorb well, such as wood, paper, cardboard, leather, many plastics, glass and coated surfaces. They are widely used in packaging, labeling and consumer goods. They are normally not the best choice for bare metals.
3. UV laser markers
UV lasers use a short wavelength and are often called cold marking because they put less heat into the part. They suit heat-sensitive plastics, thin films, glass and fine detail on small components such as electronics and medical devices. They are usually more expensive than fiber systems and are chosen where gentler marking matters.
4. Green laser markers
Green lasers sit between fiber and UV in wavelength. They are used for materials that absorb that wavelength better, such as some reflective metals and certain plastics, and for high-contrast marks on small electronic parts. They are more specialized than fiber systems.
5. MOPA fiber markers
A MOPA fiber laser is a fiber laser with adjustable pulse duration, which gives more control over how heat affects the surface. This widens the range of marks, including smoother annealing colors on stainless steel, black marks on aluminum and fine marking on plastics. They are a flexible option where many materials and mark styles share one machine.
Traceability uses
A central use of laser marking is identification. A permanent mark can carry a serial number, a batch or lot code, a date, a logo or a 2D code such as a data matrix. Following a part through machining, assembly and service by its mark supports recall handling, warranty checks and quality investigations. In regulated fields, including medical device equipment, direct part marking is often part of a broader identification system. Requirements differ by industry and region, so check the applicable rules.
For a mark to be useful, it must be readable. Many plants verify marks with a code reader or vision camera, tying into inspection sensors and wider automated quality control. Contrast, size, surface finish and the angle of reading all influence whether a code can be read reliably.
Choosing a marker
Consider:
- the materials and finishes to be marked;
- the mark type and depth required, and whether the surface must stay smooth;
- field size and part size;
- cycle time, and whether the marker will be inline on a conveyor or fed by a fixture or robot;
- the need for fume extraction;
- after-mark processes such as coating or heat treatment that might alter the mark.
Testing on actual parts is the best way to judge results. Laser markers are classified as hazardous, so follow the manufacturer’s enclosure, eyewear and interlock requirements, provide fume extraction, and use trained personnel in line with local regulations.