In this post we will talk about a marking technique called continuous mode. This type of marking can only apply on ferrous metals.
Ferrous or ferrous metals are those that contain iron as a base element. May also contain small amounts of other metals.
In spite of the inconveniences of this type of materials due to its mechanical resistance (iron, steel, stainless steel, etc.). They offer us the possibility of making a type of marking that not affect the surface of the material to treate. But will allow us to obscure the zone that comes into contact with the laser, turning completely black in some cases.
For lamp lasers or diode pumped the technique is very simple. We will have to configure the laser so that the Q-swich does not module and does not generate the pulses with which we record normally. To achieve this, we must disable the Q-swich if the software of our machine allows it or raise the frequency above 50khz. It is advisable to raise as much as the type of software allows us, 70khz, 90khz or 100khz. We must also reduce the marking speed. Since this technique requires that the laser be more time over the area to achieve color change.
The speed will depend on each particular characteristic and machine model. But between 50 and 150 mm / s would be a good parameter to start. Also the power for marking must also be high, since we need to generate a significant amount of heat to make a pseudo tempere of the material that will change its color. Between 60% and 85% of the power of the machine.
For fiber lasers, we only need to configure the machine with a positive blur that will vary depending on the watts of power of our system. Between 1 and 3 mm would be the correct parameter, high power and high speed. We just have to play with the number of passes, which must found in trial / error mode. Trying to see how many passes are necessary to obtain the desired finish.
This method of engraving slower than pulsed engraving. But it allows us a type of finish impossible to achieve with it. One of the systems to achieve this technique is the Nd: YAG fiber laser machine PC20FP.