What is the difference between laser marking and engraving metal?

From welding plastics to engraving metal, lasers have a place in every industry. If you’re relatively new to the technology, you might be wondering what’s the difference between laser marking and laser engraving – but more importantly, which process is right for you.

Laser engraver

Laser processing method of metal
The term laser marking is often used as a word to describe a set of processes. This can range from surface marking to deep engraving, both of which leave „marks“. Below are the industry standard terms we use to describe the types of tagging methods.

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ablation. The terms laser engraving and laser etching are subtypes of this process, which differ by the depth of the cavity and the way light is reflected to show contrast. Laser engraving is an umbrella term for this method.

annealing. This is the surface level change of the metal to provide contrast for legibility. Laser marking is used to describe this method more generally.
Although these terms are often used interchangeably, there are differences between laser marking, laser engraving, and laser etching.

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What is laser engraving/ablation?
Laser engraving, or ablation, is a process that involves high laser power and high-speed movement of the laser beam to rapidly vaporize material, revealing an image at eye level. This creates durable cavities in the material and is usually done before the powder coating process. Ablation can also be used to remove thin layers of materials such as paint, anodizing, and plastic films. The process called laser cleaning is a form of ablation used to remove contaminants such as rust and oil from metal, as well as to clean molds used in injection molding.

There are two main subtypes of ablation, called engraving and etching. Etching is similar to engraving, but is identified by raised edges that reflect light differently and have a shallower depth.

Engraving depths up to 0.02″ and above
Etch depth typically not more than 0.001″

Sample A was engraved using an ultrafast picosecond fiber laser. The edges are clean and the surrounding material is not affected by the heat of the laser. This is called the heat affected zone (HAZ). We discussed this topic in our previous article on the unique processing capabilities of ultrafast lasers.

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What is laser marking/annealing?
Laser marking or annealing is the process of modifying the surface properties of a material through an oxidation process to produce contrasting marks. This oxidation is accomplished by slowly heating the material at low power to attract carbon to the surface, creating a clear mark. This process works on steel and most plastics that contain carbon molecules. When annealed, material is not removed from the surface, resulting in a smooth finish.