By Alex Fraser on January 27, 2021
Laser Marking
Deep laser engraving is a process that uses a highly focused beam of light to engrave 3D forms into metals. Pulsed fiber lasers are the best tools for deep engraving because they reach the high peak power needed to carve metal surfaces.
Laser engraving and deep engraving are not so different. Deep engraving is just deeper, takes longer, and usually includes finish requirements that are pleasurable both visually and to the touch. If you have depth and aesthetic needs, keep reading to learn more.
How Deep Can You Laser Engrave?
When it comes to deep engraving, the depth can easily reach a few millimeters into metals. This is in stark contrast with regular laser engraving, which is typically only a few microns deep.
But regular laser engraving can also be deep—up to 500 microns. This is often the case with shotblast resistant laser marking.
The real difference between deep engraving and laser engraving is that deep engraving comes with depth and aesthetic requirements. On the other hand, laser engraving requires a high contrast to meet traceability requirements—just like laser etching.
What Is Deep Engraving Used For?
Deep laser engraving is used to incise 3D forms such as logos, drawings, text, serial numbers and barcodes into parts and workpieces. It is a high-quality process whose results are repeatable, uniform and precise.
This process is used in a wide range of applications. The most common are deep logo engraving, stamping plate engraving, and mold insert engraving (especially for automotive parts).
Other examples include engraving high-value metal parts like custom knobs and guns. Deep metal engraving can also be used to fully carve a 3D part or to remove material.
Can You Deep Engrave Stainless Steel?
You need to proceed with caution if you want to deep engrave stainless steel, as you will remove the protective oxide layer that prevents rusting. Stainless steel may also change colors during the process. Color changes result from specific alloys, but they’re mostly due to how the laser parameters are configured.
When the laser is configured to engrave as fast as possible, stainless steel tends to blacken. To get a clean surface finish, the process will take more time.
An important thing to keep in mind is that since the protective layer is removed, you need to prevent rusting with an additional process, such as painting, chrome plating, and so on.
What Are the Most Important Parameters?
Laser Power
When choosing a laser, one of the most important parameters needed to meet cycle time requirements is the laser power. A 500W laser may not be 5 times faster than a 100W, but it is still much faster.
Most deep engraving applications require at least 100W. At Laserax, we provide two types of lasers. Our high-power fiber laser starts at 200W. We also offer a 100W fiber laser, a less expensive option.
Deep engraving is also possible below 100W, but you may find that the engraving times are too long. We do not recommend it.
Lens
As surprising as it may sound, laser power is not the most important parameter needed to achieve a high speed when engraving. The lens is more important.
Lenses control how the laser beam is focused, and only a highly focused beam can reach the intensity required for deep engraving. Using the right lens can effectively double the engraving speed.
Our laser experts performed tests using a 254 mm lens and a 420 mm lens. Results show that the smaller lens is most effective.
| Lens and Material Used | Engraving Speed |
|---|---|
| 254 mm lens on aluminum | 0.41—0.70 mm3/s |
| 420 mm lens on aluminum | 0.22—0.36 mm3/s |
| 254 mm lens on steel | 0.05—0.11 mm3/s |
| 420 mm lens on steel | 0.04—0.09 mm3/s |
Scanning Speed
The scanning speed is the speed at which the laser beam moves. A slower scanning speed means that the laser beam remains longer over the same area. This increases the amount of energy in that area, allowing you to engrave deeper and faster. But there’s a point where too much energy may overheat and discolor the surface.
Whether you need a fast or slow scanning speed depends on your quality and cycle time requirements. The key is to find the right balance between speed and quality. When we perform sample tests for clients, we show different results and let them decide which they like best.
Part Temperature
Certain metals like aluminum can be engraved faster and deeper when they are preheated, as they reach the temperature required for ablation more quickly. Our tests showed that aluminum could be engraved up to 40% deeper within the same time.
Preheating can be done by including heating plates with the laser engraver.
Line Width
The line width is the distance that the laser beam travels over a given line before starting a new line. Whenever the laser starts a new line, there’s a small delay of about 0.03 seconds known as the hatch speed. This delay may seem insignificant, but it adds up!
For a short line width of 1 mm, the hatch speed delay can represent more than 50% of the marking time. For a longer line width of 50 mm, it may only add up to 10%.
Put simply, the longer the line width, the faster the engraving speed. For example, engraving a small logo could be done at 1 mm3/s compared to 2.51 mm3/s for a large logo. This is why we provide speed ranges for our lasers.
What Laser Engraving Machine Do You Need?
Deep laser engravers are ideally enclosed in a manually operated laser marking machine. The main reason is that deep engraving is a long process that may take several minutes for a single part, or even several hours.
Since automation is unnecessary, deep engraving machines are more affordable than other types of machines. All you need to do is launch the process, then come back and load a different part when it’s done.
What About Safety?
Regarding safety, you need to know two things.
The first one is that workers need to be protected from the laser beam. For this, all you need is a Class-1 laser safety enclosure, which is 100% safe according to international standards.
The second one is that deep engraving generates dust and fumes when it vaporizes the surface of your parts. Since a lot of material is removed, you need a laser fume extractor. This will make sure that you keep a clean air for your workers.
If you have a project and need a laser engraver, contact a laser expert to discuss your requirements and get your samples marked.
