Laser Engraving Machine

A laser engraving machine can be thought of as three main parts: a laser, a controller, and a surface. The laser is like a pencil - the beam emitted from it allows the controller to trace patterns onto the surface. The controller (usually a computer) controls the direction, intensity, speed of movement, and spread of the laser beam aimed at the surface. The surface is picked to match what the laser can act on.

There are three main genres of laser engraving machine: The most common is the X-Y table where, usually, the workpiece (surface) is stationary and the laser moves around in X and Y directions drawing vectors. Sometimes the laser engraving machine is stationary and the workpiece moves. Sometimes the workpiece moves in the Y axis and the laser engraving machine in the X axis. A second genre is for cylindrical workpieces (or flat workpieces mounted around a cylinder) where the laser engraving machine effectively traverses a fine helix and on/off laser pulsing produces the desired image on a raster basis. In the third method, both the laser and workpiece are stationary and galvo mirrors move the laser engraving machine beam over the workpiece surface. A laser engraving machine using this technology can work in either raster or vector mode.

The point where the laser touches the surface should be on the focal plane of the laser engraving machine’s optical system, and is usually synonymous with its focal point. This point is typically small, perhaps less than a fraction of a millimeter. Only the area inside this focal point is significantly affected when the laser engraving machine’s beam passes over the surface. The energy delivered by the laser engraving machine changes the surface of the material under the focal point. It may heat up the surface and subsequently vaporize the material, or perhaps the material may fracture and flake off the surface. This is how material is removed from the surface to create an engraving using a laser engraving machine.

A laser engraving machine 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. The laser engraving machine’s 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 very efficient. However, because of this efficiency, the laser engraving machine may heat up rather quickly. Hence, elaborate cooling systems are required for the laser engraving machine. Alternatively, the laser engraving machine beam may be pulsed to decrease the amount of excessive heating.

Different patterns can be engraved by programming the laser engraving machine controller to traverse a particular path for the laser beam over time. The trace of the laser engraving machine beam is carefully regulated to achieve a consistent removal depth of material. For example, criss-crossed paths are avoided to ensure that each etched surface is exposed to the laser only once, so the same amount of material is removed. The speed at which the laser engraving machine beam moves across the material is also considered in creating engraving patterns. Changing the intensity and spread of the laser engraving machine beam allows more flexibility in the design. For example, by changing the proportion of time (known as "duty-cycle") the laser is turned on during each pulse, the power delivered to the engraving surface can be controlled appropriately for the material.

Resources - Tell Me About It