What is laser etching, and how does it work?
What’s the difference between laser etching and laser engraving?
What kind of machine is required for laser etching different materials?
The answer to these questions depends upon the various factors that govern these processes.
In this article, I have discussed the laser etching process in detail and pointed out the various factors that differentiate laser etching from laser engraving.
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What is Laser Etching?
Laser etching is a process in which the surface of a material is altered to create a mark that carries information or aesthetic value.
In this process, a high-energy laser is focused on the surface of the material to create the desired mark.
The laser energy is absorbed by the material, resulting in melting and vaporization of the surface.
In some cases, the mark is created just by melting the surface without removing any material.
Melting expands the material and results in micro elevations and discoloring on the surface of the material.
Applications
Laser etching has applications in various industries like automobile, aerospace, electronics, military, etc.
It is most widely used in manufacturing industries to etch serial numbers and barcodes on the various parts and sub-assemblies of automobiles, airplanes, medical equipment, etc.
These marks carry vital information used to track the source and origin of a product throughout its life cycle.
Furthermore, laser etching is also used by artists and designers to add intricate designs to their artworks.
How to do Laser Etching
The laser etching process consists of various steps and factors that govern the etching process.
Preparing The Design
The first step in any CNC machining process is to prepare the design.
There are various laser engraver/cutter software that can be used to make the design (CAD), convert the design into G-codes (CAM), and control the process parameters.
A good design should include all the required details while maintaining the material’s structural integrity.
The width of all the design components should be greater than the depth of etching to provide structural rigidity to the etched pattern.
Check for any overlapping components in the design and rectify them.
The overlapping design would direct the laser to pass over the particular curve more than once.
This will result in a deeper groove and darker color along the curve which will affect the appearance of the etched pattern.
When using laser etching to print a photograph, it is recommended to use an image with high contrast and minimal shadows to attain a high-quality output.
Furthermore, it is recommended to use a bi-directional hatch pattern when etching in raster mode.
Selecting the Right Laser for Etching
| Type of laser | Materials it can Etch |
|---|---|
| CO2 Laser | Non-metals and some metals |
| Fiber Laser | Metals and some plastics |
| Diode Laser | Both metals and non-metals |
Type of laser for different types of materials
Different materials have different absorption rates for light energies of different wavelengths.
A CO2 laser has a wavelength of 10600 nm and is readily absorbed by non-metals like wood, plastics, fabrics, etc.
Due to this reason, a CO2 laser is an ideal choice for laser etching non-metals.
Although high-power CO2 lasers can cut through various metal surfaces, they do not perform well in engraving or etching metals.
Fiber lasers have a wavelength of 1060 nm, which is best suited for laser etching metal surfaces as metals readily absorb the energy at this wavelength.
They can also be used to perform etching on some plastics, but the quality of etching on plastics by a CO2 laser is far superior.
Moreover, MOPA fiber lasers provide the ability to control the pulse width and frequency parameters individually, enabling to produce color laser engravings on certain materials.
Diode lasers have a wavelength of 450 nm – 950 nm and are readily absorbed by both metals and non-metals.
These lasers are generally available in low-power options, which are mainly suitable for etching non-metals like wood, plastics, and fabrics.
However, with optimal parameters and good process control, you can use a diode laser to etch metal workpieces.
Process Parameters for Etching
The optimal process parameters for laser etching depend on the material and laser engraver used for etching.
Some of the most significant process parameters that affect the quality of laser etching are laser power, etching speed, spot size, etc.
| Power | Moderate (above 30W) |
| Speed | Low speed (less than engraving speed) |
| Air assist | Not recommended |
| Spot size | Minimum |
Process parameters for laser etching
Power
Laser power generally determines the ability of the laser to cut through the material.
As laser etching does not require much of the material to be removed, a laser with moderate power (generally above 30W) is recommended for laser etching.
A high-power laser is capable of producing a dark etching with high contrast but can also result in over-burning of the material.
Etching Speed
The speed of the etching directly affects the quality of the mark.
Performing the etching at high power and high speed will result in poor quality marks with less detailing.
It is generally recommended to use moderate power at low speed for a high-quality etching.
Air Assist
Air assist is the use of compressed air that protects the focusing lens and facilitates material removal by forcing the molten material out of the kerf.
Using air assist during laser etching can result in unwanted sputtering of the material over the surface and degrade etching quality.
Therefore air assist is not recommended for the laser etching process.
Spot Size
The spot size of a laser refers to the diameter of the laser beam at the point of contact with the surface of the material.
The size of the laser beam is minimum at the focal point, and therefore it is recommended to focus the beam on the surface of the material to achieve the smallest spot size.
Smaller the spot size, the higher the resolution of the mark and the higher the quality of etching will be.
Using a Laser Marking Ink
Depending upon the process parameters and the type of material, the etched mark can be white, grey, or black with different levels of darkness.
Applying a layer of laser marking ink on the surface of the material to be etched will result in a dark black etching with high contrast.
The high-energy laser melts the material and fuses the marking ink into the surface, thereby creating a permanent mark.
Using stencil or inks containing Polyvinyl chloride (PVC) is not recommended as laser cutting vinyl produces harmful fumes of sulphuric acid that can be toxic to humans and can damage the laser equipment.
Some of the most commonly used laser marking inks are:
Laser Etching vs Laser Engraving -Explained
Laser etching and laser engraving are two different processes that serve a similar purpose.
Both the processes are used to print a visible mark of desired shape and size on the surface of the workpiece.
Although both have similar functionality, there are significant differences between the two processes.
Working Depth
| Process | Working Depth (inches) |
|---|---|
| Laser Etching | 0.001 |
| Laser Engraving | 0.001-0.005 |
| Deep Laser Engraving | 0.005-0.125 |
Working depth of different laser processes
Laser etching and laser engraving print a mark on the material by altering the surface.
The primary difference between the two processes is the depth at which these processes affect the material.
Laser engraving uses a high-powered laser beam to remove the layers of the material and create a cavity in the shape of the required pattern or design.
Depending upon the depth of engraving, the engraving can be categorized as laser engraving and deep laser engraving.
Laser engraving involves material removal up to a maximum depth of 0.005 inches, whereas laser engravings deeper than 0.005 inches are considered deep laser engravings.
These engravings are generally limited to a maximum engraving depth of 0.125 inches.
On the other hand, laser etching uses a comparatively lower-powered laser to alter the material up to a maximum depth of 0.001 inches.
When comparing laser etching with laser marking and laser engraving, the mark produced by laser etching is more durable than laser marking but less durable than laser engraving.
Material Removal
Laser engraving uses the energy of the laser to burn, melt and vaporize the material up to the desired depth in desired shape and size.
Whereas laser etching does not necessarily involve vaporization of the material.
In laser etching, the marks are created on the surface of the material by either of the two methods.
The first method involves material removal by a high-energy laser beam that burns, melts, and vaporizes the material.
This creates a mark in the form of a shallow (0.001″ deep) void of desired shape and size on the surface of the material.
In the second method, the laser energy alters the physical form of the material up to a maximum depth of 0.001″.
The laser heats and melts the surface, which results in the expansion of the material.
This expansion of the material creates micro elevations on the surface of the material that highlights the required pattern or design, thereby creating a visible mark on the surface of the material.
Marking ink is generally used in the second type of etching, where the laser melts the material, and the ink gets fused with the molten material to create a permanent mark.
Speed
The working depth and material removal directly affect the speed of both processes.
As laser etching requires no or minimal material removal, it is comparatively faster than laser engraving.
This results in a shorter cycle time for laser etching which makes it preferable for marking products in mass production.
The marks produced by laser engraving are comparatively more long-lasting and are preferred for products prone to scratches and abrasion.
Frequency
The laser frequency determines the number of laser pulses per unit time (Hz) or the number of pulses per inch (ppi).
Increasing the frequency increases the number of pulses striking the surface, thereby increasing the amount of energy absorbed by the material.
However, setting the frequency too high will result in a dark mark with high contrast at the cost of clarity.
As less material is to be removed during etching, the optimal pulse frequency or pulse per inch (ppi) for etching process is relatively lower than the engraving process.
What Materials Can Be Etched By a Laser?
The type of materials that a laser can etch depends on the laser used.
Generally, a CO2 laser is used for etching non-metals, and a fiber laser is used for metals.
Diode lasers are low-powered lasers that are generally used by beginners and DIY enthusiasts to etch various types of soft materials like wood, plastics, fabrics, etc.
However, some special materials like anodized aluminum, laserable brass, etc., can also be etched by CO2 and diode lasers as they consist of a non-metallic layer on top of the base metal.
When laser etching these materials, the laser removes the upper non-metallic layer revealing the shiny metal underneath.
This adds to the aesthetics of the etched design and results in a beautiful mark with high contrast that is easily visible.
Advantages of Laser Etching
Laser etching is performed by a CNC laser engraving machine that offers various advantages over the traditional etching methods.
Quality
The quality of the etching produced by the laser etching process is far superior to that of any traditional process.
It produces a dark mark with high contrast, which generally does not require any secondary process like oxidation.
Speed and Precision
The material removal rate of a laser is faster than most of the traditional methods.
This reduces the time required for etching a material and increases the productivity.
Combining the speed with high precision enables to etch intricate designs with ease that otherwise would be difficult to etch with traditional methods.
Non-contact Process
The non-contact nature of laser etching allows creating a permanent mark on the surface of the material without inducing any unwanted mechanical stresses in the material.
Furthermore, laser etching minimizes the risk of unwanted chemical reactions of the material as there is no or minimal chemical contact for darkening the etching.
Best Laser Etching Machines
The ability of a laser etching machine depends upon various factors such as type of laser, power, speed, etc.
On the basis of these factors, here are some of the best laser etching machines available in the market.
Trotec Speedy 100
Trotec Speedy 100 offers a work area of 27” x 13.5” with a footprint of 40” x 31” x 40”.
It has a high marking speed of 110 ips, which reduces the cycle time and increases the productivity.
The feature that gives Trotec Speedy 100 an edge over other machines is its flexible laser module options.
It comes with a CO2 laser module option that has a power rating of 30W – 60W which can be used for etching various non-metal surfaces.
For those who want to etch metals, Trotec also provides an option to select a fiber laser with a power rating of 20W – 30W.
Furthermore, the Flexx technology by Trotec enables to have an all in one machine that includes both, fiber and CO2 laser for etching metals and non-metals.
Trotec provides various laser engravers under the Speedy series that offer comparatively larger work area.
| Model | Work Area | Laser Power (W) (CO2/Fiber) | Engraving Speed (ips) |
|---|---|---|---|
| Speedy 100 | 27” x 13.5” | 30-60 / 20-30 | 110 |
| Speedy 300 | 31” x 17” | 30-120 / 20-50 | 140 |
| Speedy 360 | 35” x 24” | 60-120 / 20-50 | 140 |
| Speedy 400 | 43” x 27.5” | 60-120 / 20-50 | 169 |
Different models of the Trotec Speedy series
OM Tech FM1212-50
The OM Tech FM1212-50 is a desktop laser engraver that offers a comparatively smaller work area of 7.9″×7.9″ (200×200 mm).
It houses a 50W fiber laser which makes it an ideal machine for etching metal workpieces.
The ability to focus the laser in a tight spot size of around 20 nm and the galvanometric marking system, enables to use OM Tech for etching intricate designs at high speed.
It comes with a rotary axis included in the kit that enables to etch cylindrical workpieces.
Furthermore, a 2-year part replacement warranty and US-based tech support ensures reliable after-sale services.
A more detailed review of this laser engraver can be found here – Best Fiber Laser Engravers & Cutters
High-speed Gavanometric marking system
Rotary kit included
Ortur Laser Master 2
Ortur Laser Master 2 is a budget-friendly DIY laser engraver that houses a 1.6 – 5.5W diode laser.
It provides a surprisingly large work area (around 15.5″ x 17″) for its price point and has a footprint of 21.2” x 19.68” x 5.9”.
Laser Master 2 has a remarkably high marking speed of 120 ipm and can be used for etching various non-metals and some special metals like laserable brass, and anodized aluminum.
It does not come with a safety enclosure, but Ortur offers an add-on safety enclosure that can be added to your kit at the time of purchase.
A more detailed review of this laser engraver can be found here – Ortur Laser Master 2 Review
120 inches/min high-speed etching
LaserGRBL and LightBurn compatible
Final Thoughts
Laser etching is a quick and easy way to create permanent marks on the surface of a material.
As laser etching is performed on the top surface of the material, it can be easily scratched and is not recommended for products that are prone to abrasive conditions.
The optimal parameters for laser etching vary from one setup to another, therefore it is recommended to perform test runs to find the parameters that produce the desired results.
Furthermore, laser etching metals can be dangerous as some metals reflect the laser beam, and the reflected laser can cause eye injuries.
Therefore it is strongly recommended to follow the laser safety procedures and wear the appropriate safety glasses when etching metal surfaces.
Frequently Asked Questions (FAQ)
What is laser marking, and how is it different from etching?
Laser marking is the process of creating marks on the surface of the material.
Although it sounds very similar to laser etching, there is a significant difference between them. In laser marking, there is no melting or vaporizing of material. Instead, the laser heats the surface, resulting in pigmentation of the material due to oxidation. In contrast, laser etching involves melting and/or vaporizing the top layer of the material to create a void or micro elevations that highlight a desired shape or pattern.
Can you laser etch glass?
Yes, you can laser etch glass. Laser etching glass with a 40W CO2 laser gives excellent results with a greyish-white hue that enhances the contrast of the design. Furthermore, laser etching of glass is preferred over laser engraving because it is a fragile material, and creating a deep grove can weaken the glass.
Unlike sandblasting, laser etching glass uses a focused laser beam at the desired point, eliminating the need to mask the material.
Can you remove the laser etching mark from a material?
Yes, you can remove the laser etching mark from a material.
As the mark produced by laser etching is not too deep (<0.001″) into the material, it can easily be removed using sandpaper. It is recommended to polish the material after removing the mark to restore its smooth surface finish.
