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What is a Laser Engraver and How Does it Work?

Laser engravers are machines that use a laser module to work on materials to engrave images, texts, and graphics. Most desktop laser engravers consist of the same basic components. Extruded aluminum rails, control board, stepper motors, laser module, belts and wiring. While these machines can be built from scratch, purchasing a unit with all the needed components is a massive convenience.
Assembly instructions can vary wildly from brand to brand, and some will be challenging when they're translated from a language that is foreign to your own. We've been through the struggles of building various models throughout the years, and our favorite one to assemble to date is the Sculpfun S9. It contains very well illustrated assembly instructions. They even package the hardware for each step of the assembly separately.
Getting back to the topic at hand though, laser engraving is a process that vaporizes materials into fumes to engrave permanent, deep or shallow marks based on the percentage of power you apply to the laser module. The laser beam acts as a chisel, incising marks by removing layers from the surface of certain materials, such as wood. With other materials such as canvas or cloth, you're actually burning the material to a certain degree in order to achieve the look that you're after. You can also create certain chemical reactions with some materials such as ceramic tile. You can paint over the tile with paint and create a chemical reaction between the paint and the tile to achieve engraving with a high degree of detail and depth.
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, which use computer and CNC controllers to control the laser or the work pieces movements. Some laser engravers also do laser marking jobs, 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 for the most part: 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 millimeter (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. Let's go over some types of materials that laser engravers can be effective 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 be 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.
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 painting the surface can significantly prevent the laser from reflecting away. For coated metals, on the other hand, they 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 engraving the 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.