Although all carvings look alike, there are significant differences in their craftsmanship and application.
Depending on the material removal pattern and depth, laser engraving can be divided into different categories.
Laser engraving can be divided into three main types: laser ablation, concave laser engraving, and convex laser engraving. Each of these laser engravers differs in mode of operation, depth of engraving, and type of outline created.
Besides that, some special types of laser engraving include deep laser engraving, laser marking and laser etching.
Typically, as the engraving depth increases, so does the requirement for higher laser power, increasing the cost of the laser engraver needed for the job.
However, these engravers are powerful tools that can be used to perform a variety of operations, and understanding the various factors associated with laser engraving will allow you to explore the full potential of your laser engraver.
Laser ablation is the process of removing layers of material by shining a laser beam on a surface and evaporating it.
This can be achieved by using a continuous or pulsed laser beam.
As the name implies, pulsed laser beams operate with short pulses of high-energy laser light, and the amount of material removed depends on the duration of the pulse.
Short-pulse laser beams can precisely laser engrave or cut materials with a minimal heat-affected zone, leaving surrounding areas of the material unaffected by heat.
Every material has an ablation threshold. Once that threshold is exceeded, the illuminated area evaporates into smoke.
Certain materials, such as aluminum, will reach the ablation threshold faster if preheated. In this way, they can be laser engraved faster and deeper.
Preheating can be done by using a heating plate in the working area of the laser machine.
Laser ablation has many applications in different branches of medicine such as ophthalmology, general surgery, ENT, dentistry, etc.
Concave Laser Engraving
Concave engraving is a process in which a laser beam is moved along the path of a desired pattern, creating a design in the form of a void.
As a result, the engraving achieves a concave shape, leaving the material around the motif intact.
The laser energy is kept constant throughout the process, and simple shapes such as characters and numbers are engraved in an intaglio manner.
On the other hand, laser energy changes when engraving detailed items with areas of light and dark contrast.
Concave engraving typically uses a raster design to remove material in the desired shape, making it ideal for producing intricate designs with a high level of detail.
Convex Laser Engraving
As opposed to intaglio, this process applies to the part around the pattern.
Convex engraving removes material surrounding the pattern, resulting in a lifted design.
This type of engraving is often used for letter engravings, figure outlines, and other minimal patterns that do not require a high degree of detail.
Here the laser energy is the same for all points on the pattern.
You should pay attention to laser power settings and material thickness. Since you're engraving the design, edge burn may be more prominent.
Convex engraving, while not capable of producing fine engravings, is ideal for producing complex patterns while maintaining the structural integrity of the workpiece.
Special laser technology for permanent marking
Deep Laser Engraving
Deep laser engraving differs from regular laser engraving in terms of depth and is commonly used to perform 3D laser engraving.
The main disadvantage of laser engraving compared to CNC engraving is the ability to engrave deeply. This shortcoming can be overcome by using a powerful laser.
High power pulsed fiber lasers, typically 100W or more, are used for deep laser engraving of metals, while CO2 lasers rated over 100W are suitable for deep engraving of wood.
Normal laser engraving has a maximum depth of approximately 0.02", while deep laser engraving has a depth of approximately 0.02"-0.125".
This provides the ability to engrave at varying depths to create 3D forms on the workpiece surface.
In addition to laser power, focusing lenses also play an important role in producing deep laser engravings.
A focusing lens with a tight spot will be able to focus the laser and achieve the power intensity required for deep engraving.
A higher powered laser can work faster, but it also runs the risk of burning or discoloring the surface.
Therefore, you should choose the power level so that you can laser engrave at maximum speed without burning the material.
Deep engraving of stainless steel will remove the top protection and compromise its corrosion resistance.
Therefore, it is recommended to paint or chrome-plate the engraved surface to make it rust-proof again.
Deep laser engraving is used to create logos, stamped plates, artwork, mold inserts, drawings, text, serial numbers and barcodes on surfaces of different materials.
Laser marking requires a relatively low-powered laser machine. The laser thermally oxidizes the surface of the material and creates a black mark.
This produces a high-contrast permanent mark on the workpiece surface without removing material.
It is important to note that laser marking is also sometimes referred to as "laser dark marking" or "laser coloring".
UV lasers are most commonly used to mark materials because they operate at a relatively low temperature, which prevents the material from overheating and evaporating.
Laser etching is similar to laser engraving. Their main difference is how deeply the laser affects the material.
Laser etching either melts and solidifies the material, or vaporizes the area to create an engraving.
It typically affects material to a maximum depth of approximately 1/1000".
Laser etching does not visibly alter the surface, but changes the surface finish of the metal and creates a high-contrast mark.
It can be performed on anodized, plated or bare metal surfaces.
Materials Compatible with Laser Engraving
With the proper type of laser and optimal laser power, laser engraving can be used on a variety of materials to produce permanent marks.
Laser engraving and cutting diagram
In the table below I list the laser power settings for engraving and cutting different materials.
It is important to note that laser engraving materials that contain PVC or vinyl components can produce hazardous fumes that can damage the machine and injure the operator.
Therefore, it is very important to check the composition of the material before laser engraving.
Different laser types
Depending on their source and wavelength, there are different types of lasers that can be used to engrave various materials.
Applications of Laser Engraving
Some of the main applications for laser engraving are barcode/QR marking on trophies, trophies, machine parts, electronic equipment, medical equipment, logos and badges.