While initially this question seems extremely basic, there is often a lot of confusion. When you think about it in detail, you realise that not knowing what each of these terms means could lead to a lot of confusion on the side of the buyer, and the equipment provider. This in turn can cause many problems when it comes to configuring the machine for the job.
The author of this article has been in the laser business since 1986 with different types of laser companies that provide standard as well as customised equipment for a large variety of applications. In the duration of his work, he has had to work with people known as Application Technicians who have to decide the feasibility of a project as well as the right processes as well as the laser for the task.
This type is the most common and is sort of self-explanatory in its name. This process involves creating a mark by removing or vaporizing the material. An example is Co2 laser engraving for signage. This consists of a two-ply plastic known as the “cap” made in a colour which is laminated to a contrasting colour known as the “core”. The process of engraving removes the cap and shows the core to create a sign that is attractive.
There is also engraving in the processing of metals and is used to guarantee permanence. Material is removed to create a depth involving the use of 1,064nm wavelength lasers as these types of lasers go well with metals. When a metal is engraved, the laser breaks the machined surface of the object, and this could cause rusting or oxidisation. So when you have to choose between methods, you have to choose between whether you want depth at the cost of oxidisation and if not, whether you should switch to a different option?
Annealing or precipitation marking is usually used on items of which the metal surface has to remain intact. This type of marking is usually done on surgical implants, surgical instruments, or high precision bearings. Laser marking is the process by which carbon that is present in the material is distributed in such a way using the heat of the laser to create a jet black mark. If this is done in the proper manner, there will be no risk of rusting or oxidation even under the effect of salt sprays or autoclaving. This can also be used on some types of plastic like ABS and Delrin which allow for a nice contrast when marked with a 1,064nm laser. If you tried the same thing on the same material with a Co2 laser, you will get an engraving with no contrast. All of this is dependent on the wavelength of the laser and how it reacts to the material or pigment in the material.
This types is often mixed up with laser engraving but what it actually involves is sectioning a part of or cutting shapes through a certain material. This type of laser cutting uses Co2 lasers as they interact more with the material rather than the pigment. A lot of acrylics can be used for signage, retail displays, as well as other applications. When one uses laser to cut, extra attention is taken to ensure there are “flame polished edges”. There are also instances when high powered, pulse YAGs but these are not as good as high powered Co2s. Another technology that is used to cut is water jetting which is effective on metal and stone. Other places where this is used are paper cutting, leather sectioning, and gasket cutting.
To conclude, it is important to know the difference between these terminologies so you can find the right equipment and service for your needs and requirements.