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Testing & Power Grids
The process of establishing the correct laser settings to make TherMark laser marking materials successfully bond can be time consuming because of the number of variables involved. To expedite this process, it is possible to quickly determine the optimum settings using what is known as a “power grid”. In the laser bonding process, the two most important variables are the laser power and the speed with which the beam passes over the material. A power grid is a graphic file constructed to apply different speeds and powers to different parts of the image; this allows the user to test multiple settings with a single pass of the laser, greatly reducing the time taken to find the best setting.
In the picture below, each square in the grid has a different combination of power and speed settings as illustrated in the axes. The Y axis decreases power in increments of 10% from top to bottom (100% power at the top, 30% power at the bottom), while the X axis increases speed in increments of 10% from left to right (10% speed at the left, 100% speed at the right).
As you can see, optimal marking will only take place when the right amount of energy is transferred by the laser. Section (1) shows that when power is too low and speed is too high there is not enough energy to create a bond.
Likewise, section (2) shows that too much power at a low speed causes the material to be removed, possibly causing damage to the substrate surface.
The ideal “process window” lies in section (3) of the photo. Any of these settings will produce excellent marks on the substrate. Picking a setting in the middle will allow maximum latitude for variability between machines and material. In other cases such as a production environment, the fastest speed possible to create a mark may be preferred.
In summary, when using a TherMark product for the first time on a new substrate, it is advisable to run a power grid on a scrap part in order to determine the optimal settings for your laser/substrate/material/coating combination.
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