How Does Laser Marking Work?

Laser marking is a popular, efficient and highly safe process that has allowed for a wide range of markings to be created on various materials around the world. This may be for aesthetic reasons, or perhaps to help label products, it has been adopted by many industries around the world, such as the aerospace or automotive (including e-mobility) sectors.

As one of the most important processes that our fiber lasers complete, we thought it would be worthwhile sharing more detailed information on the use of a laser marking machine, its applications and how laser marking works.

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Dark Contrast Marking

What is the marking process?

As its name alludes to, it is simply the placing of a mark on a material using a focused laser beam. This can be done on a number of materials, such as metals, ceramics, plastics and rubbers. This mark will be left at surface level and can be left in both black or colour.

It is important to note that while this process has many similarities to laser engraving, it has enough differences to be considered a process in its own right. The main difference is that the aim of laser engraving is to leave a deep engraving, while laser marking systems leave a mark at surface level.

Laser marking is often used in the aerospace industry

Laser marking is often used in the aerospace industry

The marking process, which can also be referred to as laser colouration, is generally used for things such as bar codes, QR codes, logos or other types of identification markings. While laser engraving can also be used for this if the identification mark needs to be deeper, engraving is most typically used for personalisation and customisation reasons.

How does the process work?

So, now that you know a little more about the process and what it’s used for, we want to examine how laser marking works.  It’s important to note at the beginning that this is a high speed and high precision process.

It works quickly, effectively and safely, leaving a high-quality mark on whichever material that it is working with. This may be flat surfaces, flexible materials or even complex shapes as laser marking takes place without any contact.

To laser mark, one directs a focused laser beam onto the surface of the material that they are working with, and the heat of the beam will generate a contrast between the affected area and the surrounding material.

Essentially, the beam oxidises the area underneath the surface of the area that it is targeting, causing it to change colour. The majority of markings will turn black, but some surfaces will cause a colour change instead.

A big allure with this process is that the surface layer of a material, and the material itself, isn’t damaged in any way or made uneven. No layers are removed, they are simply adapted through localised heating.

What are the different types of marking?

There are different types of laser marking machine processes, each with its own unique array of properties. We’ve covered each of these briefly below.

Annealing

The annealing process is reserved for metals. While the majority of marks produced are black, the oxidisation that occurs beneath the surface with annealing will result in a colour change. Frequently used for marking iron, the colour will be dependent on the level of heat, but typical colours are yellow, red and green.

Colour marking

With laser colour marking, the heat of the beam will cause a chemical reaction. The aim here is to create a variety of different colour shades on the material that is being worked with. The shade that will be produced is dependent on the material’s chemical composition. Colour marking is particularly popular within the jewellery industry.

Engraving

As discussed earlier, laser engraving is a process that is sufficiently different from marking to be considered an application in its own right. However, the two are often compared together, so it’s worth touching on here.

With laser engraving, the surface layer of a material will be melted and vaporised by the beam, leaving a deep engraving beneath. The level of depth can be controlled depending on the user’s requirements.

Foaming

With foaming, the laser beam will melt the area that it is working with, causing gas bubbles which will reflect the light. The areas that have been marked, therefore, will be lighter than the areas that haven’t.

Carbonising

Carbonising works in a similar way as foaming, with the end result helping to produce strong contrasts on typically bright surfaces. The laser will heat up the area it is working with, emitting gases such as oxygen or hydrogen. In its wake will be left a dark area with a much higher level of carbon concentration.

Night and day marking

This type of marking is a highly useful process, which leaves a mark that is both easy to read during the day and then illuminated at night. You will commonly find this type of marking on somewhere like a car dashboard.

Scribing

This is where a message is scribed on the material. This includes hallmarks and inscribing diamonds.

Night and day marking is used for car dashboards

Night and day marking is used for car dashboards

Where do SPI Lasers come in?

Here, we manufacture only fiber lasers, and we believe (with the data to prove it) that a fiber laser is the strongest type of laser when it comes to marking. Pulsed fiber lasers are most commonly used for this process, and they offer the user an accurate and precise beam with high peak power. We have a range of fiber laser models to suit a variety of needs when it comes to the power level or beam quality.

As well as marking use our fiber lasers for these applications too – ablation, additive manufacturing, cleaning, cutting, drilling, engraving and welding. If you would like to find out more, you can find our contact details below.

You may also like to read the following related content:

Would you like to find out more about laser marking systems?

If you would like more information on how to use a laser marking machine, then we would be happy to share our knowledge with you! You can call +44(0)1489 779696 or  contact us directly here, or find out more about our range of fiber lasers here. For regular updates, click this link.

Image credits: Clker-Free-Vector-Images, gustavmelin0 and Toby_Parsons

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