However, because of this efficiency, the equipment used in laser engraving may heat up rather quickly. The beam is highly focused and collimated-in most non-reflective materials like wood, plastics and enamel surfaces, the conversion of light energy to heat is more than efficient.
If the surface material is vaporised during laser engraving, ventilation through the use of blowers or a vacuum pump are almost always required to remove the noxious fumes and smoke arising from this process, and for removal of debris on the surface to allow the laser to continue engraving.Ī laser can remove material very efficiently because the laser beam can be designed to deliver energy to the surface in a manner which converts a high percentage of the light energy into heat. Cutting through the paint of a metal part is generally how material is laser engraved. It may heat up the surface and subsequently vaporise the material, or perhaps the material may fracture (known as "glassing" or "glassing up") and flake off the surface. The energy delivered by the laser changes the surface of the material at the focal point. Only the area inside this focal point is significantly affected when the laser beam passes over the surface. This point is typically small, perhaps less than a fraction of a millimetre (depending on the optical wavelength). The point where the laser beam touches the surface should be on the focal plane of the laser's optical system and is usually synonymous with its focal point. Laser engravers using this technology can work in either raster or vector mode. In the third genre, both the laser and workpiece are stationary and galvo mirrors move the laser beam over the workpiece surface. A second genre is for cylindrical workpieces (or flat workpieces mounted around a cylinder) where the laser effectively traverses a fine helix while on–off laser pulsing produces the desired raster image. Sometimes the workpiece moves in one axis and the laser in the other. Sometimes the laser is stationary and the workpiece moves. The most common is the X–Y table where, usually, the workpiece (surface) is stationary and the laser optics move around in two dimensions, directing the laser beam to draw vectors. There are three main genres of engraving machines. The surface is chosen to match the type of material the laser can act on. The controller determines the direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The laser is a drawing tool: the beam emitted from it allows the controller to trace patterns onto the surface. To create a clean mark, short bursts of high quality laser pulses are preferable, since they are able to transfer large amounts of energy without causing significant heating and melting of the sample.Ī laser engraving machine consists of three main parts: a laser, a controller, and a surface. The choice of lasers is important for the quality of the mark. Engraving can achieve depth of 100um and beyond, whereas laser marking is typically shallower. On harder surfaces, the mechanism of action is primarily the ablation where the focused beam of laser dislodges microscopic particles from the substrate. Depending on the materials, the laser-material interactions can be different. Laser engraving is the process of selectively removing microscopic layers of material, thus creating visible marks on the treated surface.
The machines for laser engraving and laser marking are the same, so that the two terms are sometimes confused by those without knowledge or experience in the practice. The term laser marking is also used as a generic term covering a broad spectrum of surfacing techniques including printing, hot-branding and laser bonding. These include laser-sensitive polymers and novel metal alloys. The impact of laser marking has been more pronounced for specially designed "laserable" materials and also for some paints.
The technique does not involve the use of inks, nor does it involve tool bits which contact the engraving surface and wear out, giving it an advantage over alternative engraving or marking technologies where inks or bit heads have to be replaced regularly. Laser marking, on the other hand, is a broader category of methods to leave marks on an object, which in some cases, also includes color change due to chemical/molecular alteration, charring, foaming, melting, ablation, and more.
Laser engraving is the practice of using lasers to engrave an object.
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