Deep engraving of metals | Tips Trotec Laser

In this simple step-by-step tutorial, we show you how to engrave or deep engrave metals using a MOPA laser. You will also be provided with both time-optimised and quality-optimised laser parameters for deep engraving metal material.

Laser engraving of metals

Engraving is a process that involves the removal of material from a solid surface. Given the incredibly high intensity of the laser, materials including steel, titanium and most other metals can be vaporised directly. The high pulse power of the fiber laser (with Trotec up to 10 kW peak power) and the very small laser spot diameter (with Trotec ~ 45 μm with the F-160 lens) further facilitate this process. With this method, texts, logos, serial numbers or other contents can be engraved into the material. The volume of the material is reduced and its colour is changed. The resulting brown areas consist of metal oxides (or rust), which can be cleaned with a second cleaning cycle using polishing parameters. Note that engraving on stainless steel requires high power, low frequency (which results in high power per pulse) and marking speeds of 250 - 900 mm/sec.

Comparison of the deep engraving results

Deep engraving of stainless steel

Deep engraving entails a very similar process to that of engraving. The key different is that it requires more passes. Here, we describe two key sets of parameters:

Time-optimised
Quality-optimised

Please note that the set of parameters used to achieve optimal quality (2) takes about three times as long to reach the same engraving depth. A 20 watt MOPA laser with F-160 lens is used in both cases. The time-optimised engraving results are displayed at the top of the image, and the quality-optimised engraving results are displayed at the bottom.

1. Time-optimised laser parameters

Deep engraving, in the first step, is carried out in the quickest time possible. We have specifically selected these laser parameters so that the desired engraving depth (in this case: 200 μm) is achieved as quickly as possible. Here, the quality of the deep engraving is not taken into consideration. This results in a warp of up to 100 µm. The engraving depth ranges from the desired 200 μm to 240 μm.

Parameters 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)

Quality-optimized deep engraving under the microscope

Deep engraving on metals: laser engraved quality-optimized

2. Quality-optimised laser parameters

Deep engraving, in the second step, is carried out with the best possible quality. We have selected these laser parameters to ensure that the desired engraving depth (200 µm) is achieved together with the highest quality possible. This increases the engraving time threefold, but it also means there is no warping. The engraving depth ranges from the desired 200 μm to max. 220 μm.

Parameters 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)

Endless possibilities with deep engraving metals

We are happy to advise you.

There are endless possibilities with deep engraving metals. Different parameters can be used to cater for different requirements. In the time-optimised variant, a great deal of material evaporates in a few passes (at a comparatively slow speed), and the quality-optimised variant uses significantly more (and faster) passes in order to remove the material in a more uniform and controlled manner.

Our laser experts are happy to consult with you regarding your requirements. You can also sample your materials.

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