Fiber lasers are used to carry out laser direct part marking (LDPM) on various metals. From the softer to the hardest metals, it is possible to mark individualized identifiers that takes the forms of barcode, 2D codes, logos and texts.
Our experts at Laserax recommend the use of 2D barcodes for most industrial applications, particularly DataMatrix Codes (DMCs) for the following reasons:
- DMC encoding algorithm is built to prevent the loss of information due to partial erasure of the codes.
- DMC has a very high density of information
- DMC are easily read by vision systems and handheld scanners
Want to learn more about barcodes, Data Matrix Codes and QR Codes as they relate to their uses for industrial traceability? Download our new ebook today.
Three Types of Laser Marking Used on Metals
There are three laser marking mechanisms commonly used on metals. There is laser engraving, laser etching and laser annealing.
For aluminum and many other metals, it is customary to use laser engraving or laser etching to uniquely identify products. It is possible to create markings such as the one illustrated in the image above.
For stainless steel, carbon steel, chrome, other ferrous metals and titanium, another laser marking process exists: laser annealing. Both laser engraving and laser annealing will be discussed further below.
You can also get more information on the differences between laser engraving, laser etching and other laser marking processes in this other blog post.
Laser Engraving and Laser Etching: Definition, Characteristics and Example
Laser engraving involves high power in very little time and creates crevices in the material. Shallow crevices (as shown in Figure b in the image above) reflect light beams in all directions, resulting in a pale marking. Deep crevices (as shown in Figure c ) reflect much less light, resulting in a darker mark. Laser etching is very similar except that the markings end up being deeper.
Main Characteristics of Laser Engraving and Laser Etching
- High speeds when engraving with high power lasers
- The resulting markings have good legibility (machine and human)
- Easy to automate, resulting in reduced human errors
- There are no limitations as to the size of the mark
- Used for traceability purposes in the primary metals and automotive industry.
For more information on the impact of laser marking on the surface of aluminum parts and the optical mechanism behind the change in colour for laser marking, consult Laserax’s white paper, entitled: Surface Analysis Study of Laser Marking of Aluminum published at ICSOBA 2016 conference.
A Typical Application of Laser Engraving
Here is an example of an automated laser marking machine we delivered to one of our customers in the aluminum industry in our blog post, Automation of Laser Marking System for Pick-and-place Robots.
Laser Annealing: Definition, Characteristics and Example
Laser annealing is completely different from laser engraving and laser etching. It involves relatively low power over longer periods of times. No materials are removed; however, the color of the stainless steel surface is changed. By modulating the laser parameters, we can get a rather wide array of colors, as shown in the picture above.
Main Characteristics of Laser Annealing
- Absence of nooks and crannies that helps prevent rust and oxidation
- The marks are easy to clean
- Possibility to generate some colour variations
- Slower marking process than laser engraving and laser etching.
Example of Laser Annealing
Laser annealing is often used for the identification of medical instruments. It is especially popular since regulations in the US requires Unique Identifications (UIDs) of all medical instruments.
Another typical application is the direct part marking of automotive parts that are subjected to salty environments at high temperatures.