What Laser Engraving is and how it works
Laser Engraving is based on the principle of using a laser light beam to modify the surface characteristics of the material by locally vaporising and removing material (laser ablation), passing the beam several times over the surface in order to obtain cavities with well-defined geometric properties. defined (edges, fillets, surface finish of the excavation, etc.).
In order to direct the beam during machining, a laser head is used equipped with two or more mirror galvanometers which are used to direct the beam during machining with extremely high speed and precision.
Laser engraving is used in various industrial sectors, such as jewellery, the production of mechanical components and the decoration of art objects. Furthermore, this technology is also becoming increasingly popular among private individuals, who use laser engraving to personalize objects such as smartphones, tablets, key rings and bracelets. The flexibility and precision of processing that can be achieved with a Laser Engraver are superior to any other mechanical and chemical processing method that can be compared.
Laser Engraving applications
Deep Laser Engraving
This technique is used in the construction of tools, moulds, in the identification of chassis in the automotive or in the jewellery.
It consists of incision deeply (up to a few millimetres) into the material, using a multi-pass ablation strategy.
Black Laser Engraving
In this case, Laser Engraving exploits the chemical process of oxidation of the molten material on the surface which occurs thanks to the presence of oxygen.
The surface roughness absorbs a lot of light and gives the effect of black or grayish-brown engravings on specific materials such as (aluminium, copper, brass, etc.).
White laser engraving
White engraving is a shallower process that creates smooth and highly reflective surfaces. In this process the fusion of the material is limited and it adapts perfectly to dark metals such as galvanized steel, hardened steel, etc.
The sectors of greatest interest for Laser Engravers are many, including: mechanics in general, automotive, moulds, tools, medical, jewellery, watches, etc.
A particular incision is that of Laser Cleaning, which through the removal of a surface layer of material, is used for pre-processing operations of materials (for example for the removal of oxides on metals) or finishing at the end of the processing cycle ( for example for the removal of chips or particles).
The sectors of greatest interest for Laser Cleaning applications are: mechanics in general, moulds, medical, printing and packaging, etc.
Micro Laser Engravings
Laser micro ablations are used to create laser micro engravings on the material and create patterns or simply excavations of any geometric nature.
Sometimes these processes have a functional purpose and are used to change the surface characteristics of the material (wettability, water repellency, etc.).
An important application related to micro ablation is the removal of thin film deposited on the substrate, which has wide application for the electronic and semiconductor sectors.
Laser Engraving - Usable Materials
Laser engraving of metals is one of the most widespread applications in the mechanical sector. The excellent results obtainable in terms of contrast and sharpness of the processing, accuracy of the engravings (which can reach the micron in the most demanding applications) and the possibility of leaving the nature of the metal almost unchanged, make the Laser the optimal choice for most of the applications.
The engraving processes also have characteristics of great resistance over time and allow to avoid corrosion phenomena.
Metals suitable for laser engraving are:
- Stainless steel
- Special steels
- Anodized aluminum
- Hardened metals
Plastics are now fundamental in the creation of all sorts of products and it is therefore a need to be able to use the laser for product traceability, or to engrave logos and writings. Plastics change their compatibility characteristics with laser radiation in an important way between the various families and types. This characteristic requires a careful choice of sources and technological solutions to be adopted.
The plastics that can be used for laser engraving are:
- Polyamide (PA)
- Polycarbonate (PC)
- Polyethylene (PE)
- Polyethylene terephthalate (PET)
- Acrylonitrile-butadiene-styrene (ABS)
- Polypropylene (PP)
Glass and ceramic
The processing of glass and ceramics is one of the most challenging due to the brittleness problems of the material and the normal insulation behavior it has with respect to heat sources. For many applications, lasers have replaced mechanical machining as the lack of a contact tool avoids waste related to cracks and fissures. Furthermore, even the maintenance costs of the tools are eliminated and the process times are much lower than traditional processes.
Furthermore, ceramic is a material increasingly used for electronics and sensor applications that require micromachining and that the laser can tackle with excellent results, challenging the fragility related to the various degrees of hardness of the material.
There are various sources for glass and ceramic processing, some examples are CO2 sources and UV sources, but more and more there is the use of ultra-short pulse sources (USP), which with the high peak energies of the pulses are able to accurately and quickly cut and engrave the hard surface. There are also special process measures, such as the adoption of specific spot formers that are able to limit thermal shocks and therefore allow the process speed to increase without creating waste and defects.
Organic (Wood, Leather)
Wood is an important material used for its versatility and wide availability. working with this material with the laser is simple and practical and it is possible to easily engrave both woods of all kinds (including painted ones), to create handicrafts, souvenirs, plates, pieces of furniture, toys, etc. The result that can be obtained is a clean and homogeneous engraving that cannot be obtained with other woodworking methods.
Leather and hide are resistant and rigid materials, difficult for traditional processing. The laser engraving of the leather produces a sharp contrast on the surface, with a tendency to embossing. A greater contrast is obtained with the incisions on darker skin, less in the case of fair skin. The results obtained depend on the type of skin, the laser being used, and the setting of the power, speed and frequency parameters.
Composite materials are formed by combining several materials with different properties to obtain a new material with different properties and usually superior to the starting ones. Generally a matrix material is used to which a fiber is then added. The most common laser-machinable composites are fiber reinforced polymer composites (FRP), metal matrix composites (MMC) and ceramic matrix composites (CMC). The laser can be used with these materials to successfully engrave and cut the surface by creating shapes, holes and engravings.
Why prefer a Laser Engraver to other technologies
Laser engraving compared to other technologies offers important advantages which must be considered in the selection phase:
Laser engravers allow you not to use parts in contact with the piece, being for this reason ideal for materials or products that require careful processing. Furthermore, since there are no contact tools, there are no related wear and maintenance costs.
Respect for nature (Green)
The engraving process is ecological and does not use inks and chemical materials which must then be disposed of.
Modern laser engravers consume less than a home appliance and certainly much less than many of the competing technologies, thus emitting less CO2 into the environment and being more respectful of nature.
Quality and precision of workmanship
Laser engraving are characterized by the quality and precision of the workmanship, as they exploit beams that can reach a few tens of microns. The details, the high contrasts obtainable and the chemical, thermal and corrosion resistance make Laser the main technology for high-level and indelible engraving applications over time.
The possibility of working with a laser engraver on any type of material, the easy integration into systems and lines and the digital nature of the laser management process make it flexible to adapt to any application and suitable for highly customized products.
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