Laser Etching an Introduction

In this blog we will look at laser etching and laser engraving, the differences between the two and the benefits of each. Laser etching and engraving are additional services we can offer customers and this allows us to offer products marked with images such as company logos or product part numbers.

The name Laser is actually an acronym that stands for Light Amplification by the Stimulated Emission of Radiation. In the most basic terms this means they produce an intense light that when utilised correctly can disform, melt or even vaporise materials such as metals. Lasers therefore found a place within manufacturing and have been used since the early 1960s. Initially continuous laser beams were created that allowed for laser cutting and welding to take place, and continuous lasers are still seen in many industries today for cutting and welding processes. Later in the 1960s a technique called Q-switching was created, this allowed a laser to be turned on and off extremely rapidly to create a pulsed laser beam. These pulsed lasers made it possible for laser etching and engraving to occur. However, it wasn’t until the late 1990s that computer processing and software specifically designed for lasers was integrated into laser engraving machines giving rise to the capabilities that we see today.

While laser welding and cutting has been used for some time in manufacturing, laser etching transformed from initially being used as a gimmick to create artwork on wood and other materials such as leather to now being used intensively within industry to permanently mark products with information such as barcodes, logos, date codes and product codes. This also has a lot to do with recent industrial and government legislation that requires part identification and traceability, the benefits of using laser etching are the ideal solution to these new standards.

Difference between laser engraving and etching

There are a few differences between laser etching and laser engraving which are important to note. Each style uses a fiber laser and marks the material surface with an image, lettering or numbers however each go about this in different ways and give a different overall outcome.

All lasers work by emitting laser beams, however by utilising different specific wavelengths the operator can affect the outcome. For instance Co² lasers used for welding and cutting use a wavelength of around 10,600nm whereas a fiber laser used for etching and engraving uses a wavelength of around 1,064nm. This lower wavelength effectively means the fiber laser generates more energy per pulse. This is important as the amount of energy per pulse used is what differentiates laser etching from laser engraving.

Laser etching works by altering the surface of the material, this is achieved by the laser delivering enough energy to a concentrated area of the surface to cause the material to melt and expand, when this area cools the surface roughness is changed creating a raised mark. Along with this slightly raised mark the surface is also discoloured and depending on how the operator has set the laser this can be black, white or grey in colour.

Engraving however requires an even more powerful laser or for the laser beam to pulse quicker resulting in a higher temperature. This is because engraving actually removes the surface material resulting in a cut or hole within the surface. This happens by heating the surface area to the point at which it vaporises. To produce a deeper engraving a laser may need several passes over the same area. This is why engraving takes longer to complete when compared with etching and results in only black markings. It is possible for a mix of laser engraving and laser etching to be used, this is a slower process but can result in the creation of very high contrast markings.

It would be remis at this point not to mention another type of laser marking, this is simply known as laser marking or laser annealing. This uses a laser beam that works at a lower temperature and moves slowly across the material surface in a method called discolouration. This option can create high contrast marks in different colours and does not damage the surface, however it takes a longer time to complete and can only be used on Steel, Stainless Steel and Titanium.

Benefits of Laser Etching and Engraving

The primary benefits of laser etching and engraving over other types of machined marking are due to there being no physical contact between the laser and the product meaning tool wear is no longer an issue and replacement tooling is not required, thereby cutting down on the longer term costs of marking products. Laser etching also allows for more intricate patterns to be created whether these be images, barcodes or written information and it offers better contrast over machined markings. Laser engraving can also offer deeper cut engravings which are more resistant to abrasion and are quicker to produce when compared to machine engraving saving on production time. Laser operating is also considered safer than machine marking for the operators.

As mentioned above the benefit of laser engraving over laser etching is that the markings are cut into the surface this means engraved markings are more resistant to abrasion. However, laser etching offers a higher contrast marking and can be created in black, white or grey compared with engraving which has less contrast and can only create black markings. This is why laser etching is predominantly used over laser engraving for the majority of products.