How to mark blank metals
It is possible to mark blank metals using a laser machine, however a CO2 laser source will require additional consumable products to achieve this. This is because CO2 laser sources have a wavelength of 10.6 µm which is not suitable for metal marking. Prior to laser processing the marking solution should be applied to the metal. To achieve the desired results there are several factors which need to be conisdered. These include the “power” and “speed” parameters, while the z-offset, selected resolution and lens also have a significant influence on the results.
The perfect tool for metal marking in terms of productivity and quality is the fiber laser source. Fiber lasers are available as laser plotters in the Speedy series as well as galvo lasers in the SpeedMarker and ProMarker series. The best machine to use depends on your application.
The following guide offers you a step-by-step guide for finding your desired parameters with a Speedy laser.
Important: When using a fiber laser additional focus must also be placed on the selected frequency as well as the laser power, speed and Z offset. Higher resolutions for graphics also play an important role in achieving good results, bewteen 500 and 1000 dpi resolution should be used due to the small beam diameter of approximately 25 µ.
We used a graphic comprised of 16 quadrants, corresponding to the 16 process colours for determining parameters. To find out the correct frequency, set the speed v and power P for all 16 colours to the same value. Set the resolution between 500 and 1000 dpi in the printer driver settings of JobControl®. Use "Colour" as the grid, since only with this process can the individual colours be assigned to the parameters.
Machine example: 20 watts FLP; 2.85" lens; P: 100 % ; v: 5.5 %
Now, select a frequency value for each colour. Start with the lowest frequency possible of 20,000 Hz for black and then increase the value by 5000 Hz for each successive colour. Adjust the Z offset to the desired result as well. An offset of 0.5 mm to 2 mm can result in a more homogeneous colour change.
The start frequency always depends on the laser power, since the lowest possible pulsation must match the power: Thus to achieve the nominal power, for example 20 watts, of the laser source, the frequency must be above 20 kHz.
Below this nominal frequency, the number of pulses is not sufficient to reach the maximum average power. Any value below this Hz level throttles the power.
Before processing blank metals with a CO2 laser, a marking solution must be applied.
Determining the parameters for the CO2 laser source can be done simply using the grayscale matrix. If no parameters are available, you can easily download tested parameters for the metal marking solution 'MarkSolid'.
The matrix is sent to the laser with the laser process “Relief” and a resolution of 600 dpi. After cleaning, parameters can be read directly from the material. For more information about the application of the grayscale matrix, please follow these instructions.
|CO2 with marking solution (eg MarkSolid)||Marking with fiber laser - Annealing marking|
Using a fiber laser to mark metals opens the door to additional processing methods. Depending on the chosen parameters and frequency, a white marking can be produced or deep engraving achieved.
White marking is an abrasive procedure that only changes the uppermost layer of the material, thus giving the surface a white finish. This process can also be used as a way of cleaning other processing methods, such as a deep engraving. This method uses high speed engraving and low power. We recommend a frequency between 25,000 and 50,000 Hz.
When processing engravable metal, a high power and low speed is needed. We selected a low frequency for the engraving to exploit the high pulsing peaks.