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Engraving and deep engraving of metals
MOPA lasers open up many new possibilities for marking plastics and metals, including high-contrast marking, color on certain metals, and more. Learn more about MOPA capabilities.
In this article, we'll explain how to engrave or deep engrave metals using a MOPA laser. We will also share time and quality-optimized laser parameters for deep engraving of metals to help you improve your results.
Laser engraving of metals
During the laser engraving process, material is removed from a solid surface. materials such as steel, titanium and (almost) all other metals can be vaporized directly by the high-intensity laser beam. The laser's high intensity is achieved by means of the fiber laser's high pulse power (Trotec lasers offer up to 10 kW peak power) combined with a very small laser spot diameter (with Trotec ~ 45 μm with the F-160 lens). With this method, you can engrave texts, logos, serial numbers or other contents into the material. The process reduces the material volume and changes its color. The resulting brown areas consist of metal oxides (or rust), which can be cleaned using the cleaning cycle using polishing parameters. Engraving on stainless steel requires high power, low frequency (which results in high power per pulse) and marking speeds of 250 - 900 mm/sec.
Deep engraving of stainless steel
The laser process for deep engraving is almost identical to engraving, but with more passes. In these tips we describe two different sets of parameters:
- Time-optimized
- Quality-optimized
Please note that it takes about three times as long to reach the same engraving depth using the set of parameters optimized for quality versus the time-optimized parameters. In both cases, a 20 watt MOPA laser with F-160 lens is used. The time-optimized engraving results are shown at the top of the image, and the quality-optimized engraving results are shown at the bottom.
1. Time-optimized laser parameters
This set of parameters is used when you want to produce deep engraving as quickly as possible. The laser parameters are chosen so that the desired engraving depth (in this case: 200 μm) is achieved as quickly as possible. The quality of the deep engraving is not taken into consideration here. This results in a warp of up to 100 µm. The engraving depth ranges from the desired 200 μm to 240 μm.
The following parameters are used:
| Power | Speed | Frequency | Pulse duration |
|---|---|---|---|
| 100% | 250 mm/s | 60 kHz | 200 ns |
| Focus | Filling lines distance | Passes | Engraving time |
|---|---|---|---|
| In focus | 0.03 mm bidirectional | 32 (for 200 μm depth) | 112 seconds (5x5 mm square) |
2. Quality-optimized laser parameters
Quality-optimized laser parameters, on the other hand, were designed to be used in instances when you need to perform deep engraving with the highest possible quality. The laser parameters are selected to ensure that the desired engraving depth (also 200 µm) is achieved together with the best quality. The process using these parameters takes three times as long, but there is no warping. The engraving depth ranges from the desired 200 μm to max. 220 μm.
The following parameters are used:
| Power | Speed | Frequency | Pulse duration |
|---|---|---|---|
| 100% | 900 mm/s | 180 kHz | 200 ns |
| Focus | Filling lines distance | Passes | Engraving time |
|---|---|---|---|
| In focus | 0.03 mm bidirectional | 450 (for 200 μm depth) | 375 seconds (5x5 mm square) |
Different options for deep engraving metal
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Laser marking provides a number of options for marking metals, and MOPA laser sources extends those possibilities even further. As you can see from this example, there are many possibilities with deep engraving of metals. You can use many different parameters to achieve a certain result. In the time-optimized variant, for example, a great deal of material evaporates in a few passes (at a comparatively slow speed), and the quality-optimized variant uses significantly more (and faster) passes in order to remove the material in a more uniform and controlled manner.
Access our online SpeedMarker tutorials.
Contact our laser experts with any questions or unique application requirements. We will be happy to offer you a consulatation and/or material testing.
