What is the difference between laser engraving, laser marking and laser cutting?
At first glance, this seems like a basic question, but these terms get interchanged all the time. If you think about it, this could cause confusion on both the buyer’s and supplier’s side of the equipment, causing errors and mishaps when setting up the right machine for the job.
I have been involved in the laser business since 1986, currently with Trotec, but previously with different types of laser companies providing standard and custom equipment for a wide variety of applications. In that time, I have always worked closely with application technicians who are tasked with determining the feasibility of a project and specifying the correct process AND laser for the job. So this is what I learned from them over the years.
This is the most common term and simply defined, it means that in the process of creating the mark, the material is removed or vaporized during the process. An example in our business is CO2 laser plastic engraving for signage. Often this is a two-layer plastic with one color called the “cap” laminated to a contrasting color called the “core.” The etching process removes the cap and exposes the core to create a sign that has an attractive appearance. There is also engraving in metal processing. Typically used to ensure permanence, the material is removed to create depth. This is generally a process reserved for 1064nm wavelength lasers (eg YAG), as those types of lasers couple well to metals. When engraving metals in this way, the laser is breaking up the machined surface of the object, so oxidation or oxidation can occur as a result. This would be a question at the time of the feasibility test. “Do you want depth? If so, do you realize that the base material could oxidize? Depending on the answer, the next option could be Laser Marking.
Annealing or precipitation marking is commonly used when processing metal items where the surface of the part must remain intact. Items such as surgical implants, surgical instruments, or high-precision bearings often require this type of marking. With laser marking, the heat from the laser actually redistributes the carbon in the material to create a jet-black mark with micron-level surface disruption. If done correctly, there will be no oxidation or rust, even under autoclaved or salt spray tests. Some plastics like ABS and Delrin also allow good contrast when processed with a 1064nm laser. If you were to process the same material with a CO2 laser, you would get an etched marking without contrast. This is all a matter of wavelength and how it reacts with the material OR the pigment in the material.
This is sometimes confused with laser engraving, but it actually means totally sectioning a part or cutting shapes directly through the material. Most laser cutting is done with CO2 lasers as they again interact with the material rather than the pigment within the material. We do a lot of work with acrylics that can be used for signage, retail displays, and many other applications. During cutting, special attention is paid to smooth cuts and what are called “flame polished edges”. There are times when high power pulse YAGs are used for metal cutting, but even with these materials the high power CO2s seem to do the best job. In the world of cutting, the other technology that is used is the water jet, which also does a good job on metal and stone. However, cutting doesn’t always mean thick materials. Other common applications are paper cutting, leather cutting, and even things like gasket cutting.
So, in conclusion, understanding this basic terminology while shopping for a laser or a company to work with will go a long way in strengthening your communication with the supplier and give you a better chance of meeting their needs and expectations.