LASER MARKING
Laser marking: Precise, high-contrast, durable marks for traceability
www.lasersystemseurope.com/applications/marking-engraving
An overview of the types of laser marking, the technologies involved and the industries it serves
As its name implies, laser marking involves the use of a focused continuous-wave, pulsed, or ultrashort-pulsed beam of light that interacts with the surface of a material to alter its appearance and properties. The process can be used to create precise, high-quality, high- contrast and permanent marks that are easy to read or scan, on virtually any surface. The first laser marker was
developed in 1965 for drilling holes in diamond manufacturing dies, with the use of the technology growing rapidly thereafter. CO2
lasers were
first used for marking in 1967, with the technology reaching maturity in the mid-1970s through a commercial, modern laser system. Laser marking systems are
today used in the automotive, aerospace, pharmaceutical, retail and medical device industries, among others. Laser marking is quick to carry out; the fastest commercial laser markers can now process tens of thousands of parts per hour. In addition, in comparison with other marking technologies, such as inkjet printing, marks made with lasers are often more robust, repeatable, and cheaper to produce. Furthermore, the process does not require
the use of any consumables such as ink or paper, making it more environmentally friendly than conventional marking technologies.
Types of laser marking There are a wide range of laser- marking techniques available, the choice of which will depend on the material to be marked and the quality of marking required. Each of the below methods
can be applied to create, for example: lettering on awards, trophies and jewellery; symbols and maps on signage; and serial numbers, barcodes or data matrix codes on parts used in the automotive, aerospace, electronics and medical device industries – where traceability is becoming increasingly important.
Laser engraving Laser engraving involves using a beam to remove material from the surfaces of components. During the process, the material the component is made from will absorb heat from the laser until it vaporises, creating marks in the form of depressions. The material will also react with air, causing a colour change to black
that will make the mark more distinct. As no consumables are needed to carry out laser engraving, it is generally more cost-effective than other engraving methods, for example those that rely on drill bits, which need replacing as they wear out. Furthermore, laser engraving is highly versatile; it can be carried out on a wide range of materials, including metals such as steel, aluminium, and copper, as well as certain plastics and ceramics. The depressions created by laser engraving make the resulting marks highly tactile while also being very durable. However, laser engraving
can be energy-intensive when materials such as stainless steel are to be engraved. In addition, the integrity of the surface of the material can become compromised after engraving, which in some cases can hasten the corrosion of parts used in harsh environments.
Laser etching Laser etching involves using a fibre laser to create a raised mark on the surface of a material by delivering large amounts of energy to a small, localised area.
Consequently, the surface of the material melts and expands, and its colour changes to black, grey or white depending on the parameters used. Much like laser engraving,
laser etching is a versatile process and is suitable for marking a wide range of metals including aluminium, steels, zinc, lead and magnesium, as well as non-metals such as paper, wood and plastics. Compared to laser engraving,
laser etching is a faster process that consumes less energy. This is because more energy is required to vaporise material (as is done in laser engraving) than to simply melt material (as is the case in laser etching). However, while laser engraving doesn’t have the upper hand in terms of speed and energy consumption, its marks are notably more durable than those of laser etching. This is because the depressions made with engraving have a better protection against abrasion than the elevated marks formed with etching. Laser etching elevation can
reach up to 80µm, whereas engraved marks can often be up to 500µm deep.
Medical devices such as these scissors (left), kidney dishes (middle) and syringes (right) can be laser-marked with anti-corrosive traceability codes and other key information
46 LASER SYSTEMS EUROPE THE 2023 GUIDE TO LASER SYSTEMS @LASERSYSTEMSMAG |
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Foba & NKT Photonics
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