Lasering with CNC.

As a metal-cutting manufacturing process, CNC milling is particularly suited to large-scale material removal. If, for example, moulds have to be milled out of a material, lasering is therefore significantly less efficient for contour formation. Due to the transmission effect of lasers, not all materials can be processed with the same energy efficiency, meaning that CNC milling could be more suitable for these productions. For the machining of brittle materials on which no equalising deburring takes place and which already have to be machined almost burr-free by the CNC machine, CNC laser machining makes more sense than the use of metal-cutting processes. In principle, CNC laser processing is most economical when cutting or engraving materials up to 50 millimetres thick. It is therefore particularly suitable for sheet metal processing.

CAD/CAM nesting software for CNC laser technology differs from the milling programmes. Software solutions specially developed for laser beam alignment, lens configurations and mirror calibrations must therefore be used for the processes involved in CNC-controlled laser processing. In contrast to milling machines, laser heads must be guided in such a way that gas flows are optimised, collisions with the material are avoided and pulse frequencies are adjusted at high speed.

All materials that can be melted using a laser can be processed. This also includes glass and ceramics. Attention must be paid to the respective transmission and reflection properties of the materials. Transmission is the ratio of energy that penetrates the material from the laser source. Metals, for example, have no transmission value. In addition, the energy absorption and thermal conductivity of the material also determine the setting of the laser. Wood and certain plastics can also be processed well with a CNC laser.

Both gas and solid-state lasers are used in CNC lasers. The latter are guided in the near-infrared range. These include so-called YAG lasers, fibre lasers and disc lasers, whose laser crystal differs in its functional form and orientation. Gas lasers, for example, are operated with CO2 (also known as "carbon dioxide lasers") as the laser medium. The containers for the respective gas should be large enough to allow the appropriate amount of gas to flow in during the machining processes.

CNC laser cutting is characterised by a wide range of advantages. These include, above all, the high precision with which lasers work, but also the elimination of post-processing. This is because laser cutting with CNC automatically produces clean and polished cutting edges for technical reasons. In addition, laser cutting is a very quiet technology that produces hardly any noise emissions. Fast set-up times and the non-contact operation of the laser also ensure significantly faster throughput of the individual workpieces and the associated higher productivity compared to CNC milling.

CNC milling involves mechanical processing using special milling tools. CNC laser cutting is based on the introduction of high energy into the material. As soon as the laser light hits the material, it vaporises within fractions of a second. This results in high-quality and extremely precise cuts or engravings. As the material is vaporised, no chips are formed, as is the case with CNC milling.

CNC machines are virtually maintenance-free, as the regular tool changes required for CNC milling machines due to wear are no longer necessary. In general, the maintenance requirements for CNC laser cutting machines are significantly lower. Laser diodes have a very long service life. As long as the laser diode is working at full capacity, hardly any maintenance work is required.

CNC laser cutting is completely contactless and force-free. This means that the laser neither touches the material nor exerts any form of force. As a result, the processed workpiece remains in position throughout the entire processing time without being fixed. A holding device such as a vacuum table is not required.

The integration of a CNC laser machine into existing work processes is uncomplicated and time-consuming programming is not required. To create the required file, use your usual graphics programme and simply transfer the finished information to the CNC laser using a print command.

High-power lasers, such as those used for CNC laser cutting, can cause serious damage. This applies to property damage and damage to human health. For this reason, modern lasers are housed in appropriately protected enclosures. These reliably protect people and property from the radiation. If, in exceptional cases, no protective housing is available, special protective equipment is mandatory. In addition to effective shielding of the laser, this includes special laser safety goggles and appropriate warning signs. If you operate class 3R, 3B and/or class 4 lasers, the appointment of a laser safety officer is mandatory.

In CNC laser engraving, the laser beam heats the material to such an extent that it vaporises. This creates an indentation of 10 to 50 um in the material. As the engraving consists exclusively of such indentations, it is permanent and can only be removed by removing the superficial layers.

CO2 and diode lasers are used particularly frequently for CNC laser engraving. The CO2 laser is suitable for all engravings from large-area to complex geometric figures. Diode lasers are ideal for all engravings that require shading. These include photo engravings or lettering on wood.

If used improperly, the pure energy of a laser can lead to damage to health as well as serious damage to property. For this reason, powerful lasers are located in safe protective housings that provide reliable protection against emitted radiation. If there is no protective housing, additional protective equipment such as special shielding, laser safety goggles and warning signs are mandatory. When operating class 3R, 3B and 4 lasers, the company must appoint a laser safety officer.

The power is the strength of the laser and is matched to the material and the desired result. The combination of power and speed leads to the desired result. The speed setting determines how long the laser acts on a point. The higher the speed, the shorter the laser's effect on the material. With high laser power, you achieve a different result at low speeds than with high laser power and low speed.

CNC laser engraving generates high temperatures that can damage the material being processed. After all, the laser beam delivers particularly powerful energy that is easily capable of melting the material. You can prevent damage by using a cooling system that is customised to the material and the laser. Please note that harmful vapours are produced when the material is vaporised and that an extraction system is required for engraving work.

CNC laser welding is the automated and particularly efficient variant of laser welding. The process uses a beam of light that is bundled by focussing optics. This results in a focal point of 0.2 to 2 millimetres that strikes the material. The resulting energy is so high that it is capable of rapidly melting the material surface. This narrowly limited focal point means that only minimal heat is transferred to the workpiece. This results in a high temperature difference between the workpiece and the welding point, which leads to rapid cooling of the seam. This in turn minimises the thermal distortion of the material. As with other welding processes, CNC laser welding is also used with or without filler metal for the joint. Shielding gas such as argon protects the weld pool from oxidation and the associated problems ranging from discolouration to poor stability of the weld seam.

Due to the localised input of energy, the material generally does not need to be preheated. This is because the heat input into the workpiece is so low that there is hardly any thermal distortion. However, there are numerous other advantages that speak in favour of CNC laser welding. - Weld seam offers high mechanical strength - hardly any post-processing required, as discolouration is very rare - very efficient process - visually appealing, slim weld seams - non-contact welding process minimises the effect of force on the workpiece - weld seams with high mechanical strength - suitable for many materials - highly precise results.

Laser technology for welding using a CNC machine works with high energy inputs and is therefore spot and fast. The weld seams produced are free of discolouration and visually perfect immediately after welding. This eliminates the need for the often time-consuming and costly reworking of the weld seams. Another important point is the high efficiency with which the available energy is utilised. This is optimally utilised in CNC laser welding. However, the combination of automation and high-performance technology also makes an important contribution to reducing costs thanks to the processing speed achieved.

Almost all metals and their alloys are suitable for CNC laser welding. This includes various steels and stainless steels as well as titanium and cast iron. Precious metals such as gold, silver and platinum are also suitable for laser welding.

In laser welding, a distinction is made between CW laser welding and pulsed laser welding. Pulsed laser welding is very suitable for thin components, as the molten metal cools down during the pulse pauses. This results in a smaller welding depth and a lower energy input into the workpiece. CW laser welding is also known as deep penetration welding, as it achieves large welding depths. It is very well suited for laser cladding and joint welding on base materials that are prone to cracking.

Observe the various legal regulations for CNC laser welding. The systems from isel Germany fulfil these requirements ex works. However, as the operator of the system, you are obliged to take further measures in terms of occupational safety. For CNC laser welding systems of laser classes 3R, 3B and 4 and higher, you must appoint a laser safety officer.