Below are some basic information that should be known novice user to have an idea how a laser works.
How does the laser cuts and engraves?
Before making a final decision on the purchase of a laser cutter & engraver we need to know what to expect from him. From the many available on the market for CO2 lasers we should choose the most optimal for the work that we will perform in the future. To know what we can expect from the laser we need to know how it works.
The construction of the glass laser tube is virtually identical in all machines. An important difference is the length and quality of the laser tube. Different lengths correspond to different power. This affects the speed of work and allows faster processing of the cutting. We will try to present it at the example of the LiquiLaser PRO 50×30 and the LIQUIlaser BASIC 30×20. The principle of operation of other CO2 lasers is identical.
Machine control by software
Both machines will be controlled by a computer as an external device, so you can operate the engraving and cutting of the machine with the software installed in the computer, for example Corellaser or RDWorks. We use the software Corellaser in our BASIC models, it can determine the maximum page size, so in our example the laser will be working in the area of 320 x 260 mm. This is the working surface of the laser and the object needs to fit into the measurements to be engraved or cutted.
Scheme of the laser
The laser beam is emitted by the laser tube on the back of the device. By reflection from the individual mirrors and lens gets passed to the operating space. It is reflected at a right angle from the mirror and is transmitted in the direction of the laser head. Here the laser beam is reflected from the last mirror in the direction of the workpiece. At the end of the laser head is placed the focusing lens. It brings together the radius of the laser beam on the material. The carriage moves along the movable guide of the material (X-axis). The carriage guide and the mirror move across the material (Y axis). In this way, the carriage can be found anywhere on the material.
The distance between the laser head and the material can be adjusted. This allows the placement of materials with different thicknesses.
The laser head in the LiquiLaser PRO 50×30 can be moved using the arrows on the control panel. In this case, we have the ability to accurately adjust the zero point where the laser begins to cut or engrave. Very helpful is the red laser pointer mounted around the laser head. This red shining light pointer allows you to control the place where the laser starts to engrave or to control the arrangement of the material.
In the LiquiLaser’s PRO controller display you can change the position and speed of the laser head, select the files to be engraved with a USB stick or in the memory of laser. You can change the operating parameters for engraving or cutting and interrupt and resume the work of the laser at any time. The engraver remembers the last file so in case of an interruption of the electricity, we can repeat the work.
The laser head of our BASIC machines is controlled by the software every 10, up to every milimeter. The laser power can be determined from the control panel, the speed and other parameter will be controlled directly by the software.
Mode of operation of the laser when engraving or cutting is determined by several parameters: power, speed and resolution dpi. You can set them directly in the prepared file to be sent to the laser. The LCD screen of our LiquiLaser PRO displays the speed of the laser head, the minimum and maximum the power of the laser beam.
This is the beam power light beam emitted by a laser tube. The laser use for engraving the service capacity of 25 to 100 watts. 60 Watt power is quite sufficient for normal operation of conventional materials. It is also a protection for the future in case of power loss of the laser tube. More power is useful in devices for mass production. Thanks to it, we can shorten the time for cutting various materials.
The software does not adjust the laser power directly in Watts, but in percentage for processing the material. Each material has a different structure and different performance requirements. Dirtying of the optical system and the wear of the laser tube has an impact on the results of the engraving or cutting. Air blowing placed at the head always reduces the dirtying of the common lens. The depth of the engraving depends on the elected laser power.
The stronger the power, the deeper is the engraving. The lifetime of the laser tube reduces if we work already at maximum power. We can increase the engraving depth by lowering the speed or reduce the resolution dpi of the file.
Engraving or cutting speed
This is the speed the laser head is moving along the material to engrave or cut it. The parameter in the software is mm/sec. For each material we set a different speed for engraving or cutting. Higher speed always means faster laser operation. The speed depends on the depth of the engraving. If the speed of the laser operation is too high, we can not get the expected result because the design will be engraved very poorly. To have better engraving depth with the same laser power as before we need to reduce the speed of the laser engraving.
You can increase the speed and reduce the line screen for a lower engraving depth. In case of laser machines with 40 or 60W laser power and materials such as wood, glass, laminates, aluminum, leather, paper – usually must be operated with the power of 20% to 60%, and the corresponding result is achieved
by reducing the speeds of up to 20% of maximum.
Just as the printing plotter solutions, the resolution depends on the quality of the engraved image. It is given in the amount of dots fired by the laser in centimeter distance by the head – or dpi (dots per inch). The higher the resolution, the more accurately rendered fine details drawing and tonal gradations we will have, but also a long time engraving.
Possible settings are resolutions up to 1000 dpi but it works well with 500 dpi normally. With very precise work on some materials you should increase the dpi to 1000, for example, by engraving a photo and its delicated gradations (in pitches). With less accurate work the resolution can be reduced, for example. When you engrave large letters the reduction of line screen will not cause a large loss of quality, but really speed up the job. The resolution affects the duration of the work, because the lower resolution laser has to do less movement – horizontal lines).
The resolution does not correspond exactly to what is understood as a resolution in the printing plotters. You can specify it as a positioning accuracy of the laser beam. Now the question is why? As the laser burns the material as a homogeneous beam and burning is not only the radius in which the beam falls but also the side of the engraving material, because the heat spreads (for example engraving laminates or metacrylate).
Each material behaves differently when it will be engraves because it has a different structure. Final results for each material are different – wood, paper, leather, plex, glass, aluminum, and many more. The resolution dpi affects visually only on the quality of engraving. Cutting doesnt have any noticeable effect.
The order of engraving and cutting
The order of the engraving depends on the color of the object (layer). If all the objects have the same color they will be engraved at the same time with the same power and speed. If they distinguish in their colors they will be engraved in the order of colors or in the order they are exported. With colors mixed a raster will be created.
When cutting it looks different. What matters is the order of the layers of colors, but among the objects of the same color counts location on the “layers”. First cut objects are lying underneath, then those on the successive layers. Awareness of these facts is very important when cutting. For example, we cut the letter “A”. First, cut out the center – one falls out, then cut out the outer shape to give the desired end result. If you first cut out the outer contour of the letters, and she would go out of plate material, -not will then cut inside! So when cutting, it is important to separate letters or objects to curves, and those that are inside other move to the bottom (eg .: in Corel Ctrl + PgDn).
To save time when engraving an object you should lay the object on to the table and engrave along the X axis. But why? For example we have arranged to engrave an inscription on a rectangle 50 x 20 mm. The laser beam is emitted over the entire length of 50 mm. If we arrange the object along the Y-axis laser will emit a beam along a length of 20 mm performing very fast and short movements. The laser head has to accelerate and brake before and after the movement . It takes always more time if we arrange the object along the Y-axis.
Attention: It is not possible to cut from the JPG or bitmap file.