What is Laser Engraver and How Does it Work?

Laser engravers are machines that use laser to work on materials to engrave images, texts, graphics. Laser engraving is a process that vaporizes materials into fumes to engrave permanent, deep marks. The laser beam acts as a chisel, incising marks by removing layers from the surface of the material. The laser hits localized areas with massive levels of energy to generate the high heat required for vaporization. Nowadays, most laser engravers are CNC machines(链接到CNC文章), which use computer and CNC controllers to control the laser or the work pieces movements. Some laser engraver also do laser marking job, laser marking is a broader category of methods to leave marks on an object, which also includes color change due to chemical/molecular alteration, charring, foaming, melting, ablation, and more.

A laser engraver consists of three main parts: a laser, a controller, and a surface. The laser is a drawing tool: the beam emitted from it allows the controller to trace patterns onto the surface. The controller determines the direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The surface is chosen to match the type of material the laser can act on.

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. This point is typically small, perhaps less than a fraction of a millimetre (depending on the optical wavelength). Only the area inside this focal point is significantly affected when the laser beam passes over the surface. The energy delivered by the laser changes the surface of the material at the focal point. It may heat up the surface and subsequently vaporize the material, or perhaps the material may fracture (known as “glassing” or “glassing up”) and flake off the surface. Cutting through the paint of a metal part is generally how material is laser engraved. Types of materials that can laser engravers work on:
1.One of the most common materials that laser engravers work on is natural materials, especially wood. The laser power required to engrave wood is often less than 10 watts. Hardwoods like walnut, mahogany and maple produce good results. Softwoods can be judiciously engraved but tend to vaporized at less-consistent depths. Laser marking softwood requires the lowest power levels. If you want to work on softwoods with strong laser power, it is recommended to active cooling, for example a fan with sufficient airflow to inhibit ignition. Hard papers and fiberboard also can be engraved.
2.Most types of plastics can be engraved. The laser irradiation can generate direct chemical modifications, melting or evaporation of the material. Plastics are rarely seen in their pure state because several additives are used such as colorants, ultraviolet retardants, release agents, etc. These additives impact the result of laser marking. Standard cast acrylic plastic, acrylic plastic sheet, and other cast resins generally laser very well. A commonly engraved award is a cast acrylic shape designed to be lasered from the back side. Styrene (as in compact disc cases) and many of the thermoforming plastics will tend to melt around the edge of the engraving spot. The result is usually “soft” and has no “etch” contrast. 
3.Metals are heat resistant materials, marking metals requires high-density laser irradiation. For non-coated metals especially those has reflective surface, laser may be reflective away from the engraving spot leaving on enough power for metal vaporization, black-paint the surface can significantly prevent the laser from reflecting away. For Coated metals, on the other hand, can be easily engraved with clean and impressive details without black-painting on.
4.Stone and glass do not turn gaseous very easily, but when a laser hits glass or stone, something else interesting happens: it fractures. Pores in the surface expose natural grains and crystalline “stubs” which, when heated very quickly, can separate a microscopic sized “chip” from the surface because the hot piece is expanding relative to its surroundings. So lasers are indeed used to engrave on glass, and if the power, speed and focus are just right, excellent results can be achieved.
5.As with regular etched mirrors, the initial focus of laser engraving machines was to etch an image onto the glass surface of the mirror. When power, focus and speed are optimized, similar results to sandblasting or chemical etching can be achieved. In a new form of mirror engravingthe laser pulsates through the reflective silver layer at the rear of the mirror. As a result, the glass side of a laser engraved mirror remains intact, maintaining the full reflective qualities of the original mirror.

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