Laser cutting of parts is a modern and today the main technology for the production of high-precision complex mechanisms for a wide variety of industries, from medicine to mechanical engineering. This is a high-tech, fast and flexible process that can significantly reduce the cost of materials and get high-quality products as a result. We will consider all the nuances of this cutting technology in this article.
Features for laser cutting parts
Laser cutting in world industrial production is referred to as LBC (Laser Beam Cutting). The essence of the technology is to heat the cutting zone and the subsequent destruction of the material in this zone by a laser.
For metal cutting, a special setup is used that generates a laser beam that focuses on a small area of the treated area, creating high-density energy. This energy is enough for the active destruction of the material in the cutting zone (melting, combustion, evaporation, etc.).
This technology has obvious advantages, thanks to which it is widely used in metal cutting, in particular for production:
- Nodes of machine-building units.
- Elements of shelving, trade equipment and decorative products.
- Details of boilers, tanks and chimneys.
- Forged products for fences, various elements for doors and gates.
- Designer cabinets and cases for individual orders.
- Original letters and stencils for signage.
Due to the advantages of laser cutting over other types of metal processing, an increasing number of enterprises are using this technology as the main one in their production.
During the cutting process, a sheet of metal is burned through by a laser. The peculiarity of such cutting is that there is no direct contact of the cutting head with the processed material. Therefore, this technology is applicable to the most diverse in strength and brittleness of materials. The laser equally well cuts both thin sheet steel and refractory metals.
Laser cutting shows the greatest efficiency in the case of unit production or in the manufacture of small batches of the product, since the creation of any forms for metal processing is not required, therefore, there are no associated costs. Laser treatment is applied to steel of all grades and conditions, aluminum and its alloys, brass and copper.
The main advantage of this technology is minimal human intervention in the production process and a high degree of automation. In the macro-program block, it is required to set the parameters of the product geometry, the block will then independently start controlling the laser and the workpiece table. The laser focus is also automatically adjusted by changing the distance to the workpiece depending on the cutting efficiency.
See also: Types of metal cutting
Laser cutting technology
As already mentioned, cutting is carried out through the action of a focused laser beam under the control of the operator. The edges of the resulting cut are processed automatically and do not require subsequent fine-tuning. In the process of creating any product, there is no mechanical contact with the workpiece, so even fragile materials such as plastic and any kind of glass are suitable for such cutting.
Laser cutting of parts requires special equipment, including a coordinate table from 1500 to 2500 mm, which allows you to create any geometric shapes from a rough workpiece, both flat and complex three-dimensional.
The automatic process is controlled by software installed on the equipment and accepting text and graphic source information for processing. The laser heats up during operation, air cooling or exposure to a coolant, most often water, are used to cool it. Cutting performance can be improved by increasing the power of the laser beam. The consumption of laser cutting is reduced due to the fact that it is performed close to the workpiece.
Laser metal cutting uses machines with a laser energy density of 108 W / sq. see. Such a concentration of energy can be achieved due to the properties of the laser beam. We list three of its important properties.
- Unlike ordinary light rays, a laser beam has a constant wavelength (that is, it is monochromatic). This makes it much easier to focus the beam with conventional optical lenses on the surface of any material.
- The laser beam has a very small angle of divergence and, as a result, a high directivity. This feature also makes it easy to achieve the highest degree of focus on equipment.
- Another important physical property of the laser beam is coherence. The property lies in the ordering of the beam waves, which enter into resonance with each other and thereby multiply increase the total radiation power.
The processes occurring during metal processing can be clearly seen on the attached video. The laser beam, reaching the metal surface, quickly heats it and then melts it within the treated zone.
The melting zone quickly extends deep into the workpiece due to several factors, and the thermal conductivity of the material also affects this. If we continue to further influence the metal with the beam, the temperature of its surface in contact with the beam will reach the boiling point, as a result of which the metal will begin to evaporate.
Two main methods of laser metal cutting are used:
- fusion cutting;
- cutting by evaporation of metal.
Very powerful equipment is required for cutting metal by evaporation, which entails increased energy consumption. Economically, this is not always advisable. Therefore, for this method, restrictions are introduced on the thickness of the processed material. Use this method only for cutting thin-walled products.
Types of equipment for laser cutting of parts
Today, there are three types of this equipment.
- Gas installations for laser cutting. In these installations, the atoms of the supplied gas are excited by electric discharges, as a result of which the gas emits monochromatic light. The gas used as a working fluid can be pumped both along the longitudinal and transverse patterns. The most common carbon dioxide used in slit-like installations. These installations are compact, easy to operate and at the same time quite high power. The operation of such installations is clearly shown in numerous videos on the Internet.
- Solid state type installations. Structurally, this type of installation consists of a pump lamp and a working fluid. An artificial ruby rod with the inclusion of neodymium yttrium garnet is usually used as the latter. The pump lamp on this equipment is needed to transfer radiation to the working fluid. The most widely used models with a pulsed mode of operation. There are also installations operating in continuous mode.
- Gas-dynamic equipment. Gas-dynamic installations preheat the gas to 2000-3000 degrees Celsius, after which the heated working gas is directed through the nozzle, while achieving supersonic speed, and then it is cooled. This technology greatly affects the final price of equipment, the high cost of which significantly limits its use.
By demonstrating the operation of the installation, it is quite difficult to understand the equipment belonging to a certain group. To understand, you need to know the device of this equipment.
Regardless of which group the installation belongs to, the following components will always comprise it:
- a gas generation and transmission system, also responsible for radiation and consisting in turn of a gas supply device, a nozzle, an alignment laser, various optical and other elements;
- a radiator with resonator mirrors, which includes an active medium, a pump and modulation system (in cases where it is necessary);
- general management and control system;
- a mechanism that moves the workpiece and the directing beam of the laser.
Requirements for drawings for laser cutting of parts
Especially for such part processing drawings are developed in AutoCAD or CorelDraw formats.
Drawing files must meet certain requirements depending on their format.
In AutoCAD format:
- Recommended software version: AutoCAD 2000.
- The scale of the drawing is 1: 1, the coordinate system is world, the representation of the drawing is two-dimensional.
- Used types of lines: closed Arc and Line. Spline type is not valid.
In CorelDraw format:
- Recommended software version: 6-14.
- Text and character elements must be converted to Curves type curves.
- The width of all curves should be fixed and stored in the Hairlilne constant.
- Scale drawing 1: 1.
- All contours in the drawing must be created by one closed element.
The equipment supports drawing files in CDR formats (CorelDraw 14 and above), DXF and DWG (AutoCAD versions up to and including 2007).
The external contour of the part in the schematic drawing should be closed. Inside the part there may be closed contours of holes and open lines of slots.
Basic requirements for drawings:
- Scale 1: 1.
- The external contour and the contours of the holes must be closed.
- The lines created by the LINE, CIRCLE, ARC commands are supported.
- Contours created using the SPLINE and ELLIPSE tools are not supported by the installed software.
- For a high-quality and even cut, it is recommended to combine very small lines into larger ones.
- Overlapping lines on each other must be avoided, otherwise the laser beam in the overlay will pass several times at idle.
- The drawing should contain the name of the material and the number of parts.
- Each file should contain only one drawing.
- The layout of the parts in the drawing is optional.
The workpiece for cutting should go beyond the contour of the part by 5-10 mm. In CorelDraw drawings, the outline of letters and symbols must be drawn at least 2 times. Curved line segments should be divided into elementary point fragments.
Laser cutting of a part is quite accurate, its deviation from the drawing does not exceed 0.03 mm. For steel workpieces with a thickness of 4 mm, a cut width of 0.3 mm is selected. When the beam is first cut into the material, however, a hole is created that is much larger than the cut width in diameter.
The 4 most common misconceptions associated with laser cutting parts
Despite the growing popularity of this technology, popular misconceptions associated with it still occur.
- This is the latest technology.
In fact, cutting metal with a laser first made itself felt back in 1960. This technology reached mass production by 1980. Today it covers a huge number of different fields of application.
- This is a sophisticated technology.
This is an absolute myth, since even standard mechanical cutting of a product is technically more difficult than laser processing. During laser processing, it is not necessary to switch equipment and prepare a new sample each time you go to the next part. Each new order is loaded programmatically in the form of a drawing in the appropriate format. The only difficulty here is financial, since laser cutting machines are relatively expensive and require subsequent maintenance costs. For the rest, the cutting process at this installation is no more complicated than printing a picture on a printer.
- The laser beam burns through the material.
Here you need to figure it out. When processing wood with a laser, the edges of the material are really carbonized. However, for example, this does not apply to metal, since the edges along the cut of the metal are not carbonized, combustion does not occur, and the dimensions of the obtained product coincide with the set ones. In the process of laser cutting of soft materials, for example, plastic, the contact area of the laser beam with the material is too small for combustion to occur. The molten parts of the material are subsequently blown out with auxiliary gas (nitrogen or oxygen), which simultaneously cools the surfaces in the cut area. If the edges of plastic products are compacted during laser cutting, hardening areas are formed in metal blanks, which are difficult to process in the future.
- The laser beam will cope with any thickness of the material.
Laser cutting is used for different materials, however, their allowable thickness for cutting is limited depending on the technology used. Therefore, before cutting, you should choose from the available technologies suitable for the material. In any case, it is not worth refusing to use a laser in advance – the cost of this technology may pay off in the future.
Advantages and disadvantages of laser cutting of parts
First of all, we consider the advantages of laser cutting of metal parts over other processing methods. Among the many advantages, we highlight the most significant.
Advantages of laser cutting of parts:
- A wide range of allowable thicknesses of parts. Steel billets can have a thickness of 0.2-20 mm, copper and brass – 0.2-15 mm, parts made of aluminum alloys – 0.2-20 mm, stainless steel – up to 50 mm.
- There is no mechanical contact with the product. This makes it possible to cut even brittle materials without damaging them.
- Ease of setting the desired parameters for the future part. All you need is to download a drawing in a compatible format into the firmware. The equipment will perform the rest of the work on this drawing independently and with a minimum error (up to 0.1 mm).
- High processing speed of sheet steel and hard alloys.
- Ease of manufacturing small batches of products. The use of a laser is especially appropriate in these cases, since there is no need for expensive casting and stamping operations, and there are no associated costs.
- Low cost of products associated with high cutting speed and equipment performance. The volume of waste is also minimized, there is no need for subsequent processing of products.
Disadvantages of laser cutting of parts:
Laser cutting equipment is versatile, has high power and productivity. However, this equipment has certain disadvantages.
- Although the cost of the products obtained is not high, it is still higher than when manufacturing parts by stamping. Although the cost of manufacturing tooling is not included in the cost of stamping.
- Part thickness is limited by cutting technology.
Cutting of parts from various metals and other materials
Laser cutting of aluminum parts.
Due to the ability of aluminum to absorb the laser beam and the high thermal conductivity of this metal, it requires a high beam power to cut it. A laser cutting machine for any metal, including aluminum, requires special software in which the necessary cutting parameters will be set. The equipment itself can easily be used both in industry and for private needs.
To determine the necessary laser power when cutting aluminum, you need to know the parameters of the workpieces, including their dimensions. To ensure that the surface of the product is smooth, accurate and free of burrs, and also to avoid deformation of the part during operation, you should choose a low metal cutting speed.
Due to the lack of physical contact with aluminum, high quality of manufactured products is achieved. In addition, the installation has a purge zone, which also provides the most even outlines of the received parts.
On a CNC machine, the laser beam can be focused in the right direction. This allows you to get the product of any complexity as a result, provided that the parameters are set correctly.
Laser cutting of stainless steel parts.
Stainless steel is very resistant to laser and other external factors, so the laser cutting process of stainless steel is a certain difficulty. Nevertheless, laser cutting is the most effective type of cutting stainless steel.
During laser metal processing, protection against oxidation that occurs on the surface of the workpiece is required. To do this, a layer of nitric acid is applied to the surface, which protects the metal from ignition.
Auxiliary gas should be supplied to the working area under a pressure of 20 atm. The thicker the sheet of metal, the larger the cross-sectional size of the material and the greater the amount of nitrogen must be supplied to the treated area.
Laser cutting of copper parts.
Copper has a high thermal conductivity. This must be considered when working with copper parts. In particular, the cutting speed of a copper product should be small, and the laser beam power should be as high as possible. Otherwise, the cutting quality will be low – the cut line will be uneven, with areas of deformation of the cut edge.
It is difficult to cut large thicknesses with a laser. Especially powerful equipment is needed, which entails an increase in its cost and the total cost of the work. In this laser cutting thick sheets of copper can only be cut. Products of complex shapes cannot be made.
The cutting of copper parts is preferably performed by solid-state beams. In other cases, you can get deformed products. During the cutting of thick sheets of copper, a plasma is formed in the cut zone, heating and melting the metal when the melting point is reached.
Laser cutting of brass parts.
Brass is actively used for laser processing, both in industrial production and in the piece manufacture of parts using manual labor. Steel and brass are very easy to laser cut. It is also not difficult to control the process – it is enough to set the necessary parameters in the system and you can get a product shape of any complexity at the output.
Laser cutting of titanium parts.
Titanium and its alloys give an active reaction when exposed to oxygen and nitrogen. In the case of using oxygen as an auxiliary gas, a layer of oxides and nitrides is formed on the surface of the cut in a solid and brittle state. The resulting details will be unsuitable for many tasks. An approximate reaction gives nitrogen. Therefore, inert gases such as argon and helium should be used for laser cutting of titanium. Argon is cheaper than helium, but its use can lead to some difficulties. As a result of overheating of the cut surface, a change in the phase state of the material in the working zone is possible (formation of an alpha structure). In this case, the fatigue strength of titanium decreases, and the product becomes unsuitable for use in the aerospace industry. Helium has a high heat capacity and thermal conductivity, so it is often mixed with argon to cool the cutting area. As a rule, a 25% helium content in the total mixture with argon is sufficient; however, in some cases its proportion in the mixture is increased to 50%.
Laser cutting of plywood parts.
Today, laser cutting of plywood and wood parts is quite popular. This technology makes it possible to realize the most daring design and engineering ideas thanks to the ultra-thin laser beam (less than a millimeter in diameter). The result is products with high detail and complex shape, while giving a tiny amount of waste.
Ideal for laser cutting veneers with a thickness of 0.6 mm or more. The cut on such a material always remains even and smooth, without carbonization and darkening. Product quality also depends on the wood of which the plywood is made, as well as the glue used. The most suitable for laser processing is plywood from coniferous wood, purified from resin.
With the help of laser cutting, the so-called busy boards are created from plywood elements – developmental stands for children with numerous switches, buttons, latches and other details that attract small children. In addition, the business board can contain various toys and other objects of different shapes, colors and textures. All this can be touched, switched, pressed and done all that, as a rule, small children with real details are not allowed to do.
Laser cutting of plastic parts.
The modern world has almost captured plastic. Having cheapness, sufficient strength, durability and resistance to temperature fluctuations, plastic has found application in all sectors of human activity.
Plates, signs, dressing numbers, stencils, various advertising and gift products are made of plastic blanks in this way.
However, not every plastic is suitable for laser cutting. For processing PVC and materials containing PVC, it is better to use a milling machine.
Laser cutting of acrylic parts.
Acrylic was the first material to test the new laser cutting technology. The peculiarity of this material is that when exposed to a laser, acrylic evaporates without leaving any traces.
Details obtained by this method are used in advertising and trading business, in science. Acrylic is also used to make souvenirs in this way. Because acrylic is easy to cut with a laser beam, the result is details with smooth and neat edges.
The resulting products can have the most bizarre shapes and complex patterns. The width of the cut depends on the material used. Another feature of acrylic is that it actively interacts with the laser beam only along the narrow working area of the cut, the rest of it remains unchanged. As a result, the edges of the products are smooth, without cracks and chips, so the products do not need further processing.