05 Feb What is Laser Marking?
What is laser marking and how does it work?
Laser cutting and engraving are the most common terms used when referring to modifying the surface of a material with a laser. Marking is less frequently mentioned, but just as effective for many purposes. It is one of many uses for industrial lasers as well cutting and engraving.
It’s main difference to engraving, is that it does not remove areas of the material. Instead, it heats up the surface causing its colour to alter, permanently marking the material. As with any laser application, this is much more effective than manually modifying the material.
Types of laser marking
There are a number of variations, the following methods are the most common, and each form is achievable on our fiber engravers. The versatility of these machines means you can change the settings to achieve completely different results. These variations include:
- Annealing – A process in which the beam heats up the surface enough to finely oxidise it. The process is used on metals containing carbon e.g. titanium.
- Carbon Migration – Heat from the laser raises carbon molecules to the materials surface resulting in a dark marking. This is another variation suitable for only carbon-containing metals.
- Foaming – Foaming is a variation used on plastics, particularly dark ones. The focused material is melted creating a foamy appearance that remains sealed once the material has cooled down. This reduces the density of the focused area, therefore allows light to pass through it, leaving a light, smooth marking.
- Colouration/discolouration – The laser heats the material enough to oxidise its surface, altering its colour. The result depends on the type and colour of material used, but can leave a contrasting finish on any colour of material.
Comprehensive Materials Processing provides scientific background on various types of marking.
CO2 Laser Markers
It is important to note that unlike fibre markers and cutters, CO2 lasers aren’t designed to cut, engrave or mark metals. However, you can mark coated metals, removing coating to reveal the underlying metal. This is a very common way of personalising objects. You can also add a marking compound to the material to achieve a similar finish. This is a fairly simple method, yet leaves a stunning, bright finish. MarkSolid Spray and Paste is designed specifically for this application. To use; apply the solution, allow 15-20 minutes to dry, laser the material, wipe of excess compound with a cloth and IPA solution.
Materials that can be marked include but are not limited to:
- Coated metals
- Uncoated metals
Examples of laser marking application
There are many applications of marking dependent on requirements. One of the most popular is text and figures.
The precision of marking is perfect for serial and batch numbers, bar codes etc. They have no problem producing letters and numbers easily readable to the human eye, but can even create lettering so small it’s only recognised with magnifying equipment or automated technology.
‘Night and day marking’ is another widely used application. This allows material markings to be seen in light and dark (with backlighting), as used in laptop keyboards, car dashboards and drinks machines.
Benefits of laser marking
- Extremely high production speed
- Structural integrity of the lasered material isn’t hindered as the change is minuscule
- The nature of the process minimises waste and mess
- Use of codes are extremely useful for traceability and accountability
- The finish is permanent and highly resistant to fading due to wear