Metal laser cutting

Table of Contents

What is laser metal cutting?

Metal laser cutting is used to the process of heating and destroying metal using a laser beam. The international name of the technology is Laser Beam Cutting (LBC).

To date, there are 3 main ways to work with a laser for metal

  1. Melting is the most common method, which is suitable for a large number of materials. The laser beam heats the metal surface to the melting point, which differs for the types of raw materials. With a properly selected mode, the metal is melted only along the cut, the integrity of the edges is maintained. A stream of compressed gas beats into the processing zone, which blows out the molten metal, cools the edges, and prevents melting and deformation on the cuts. For example, the presence of oxygen when cutting stainless steel or aluminum threatens to oxidize the cut, so the surface is blown with nitrogen. The movement algorithm is compiled on the basis of information about the material (thickness, melting temperature) and embedded in the software that controls the equipment. This technology is characterized by high accuracy, speed and economy.
  2. Combustion is a metal laser cutting method that optimizes the processing of ferrous metals, but is not suitable for non-ferrous metals and steels with a high alloy content. Exposure to oxygen gives several times more thermal energy than the operation of a laser. Process cost and processing time are reduced. The technique has a drawback – the edges of some materials burn. The post-processing costs of slices can outweigh the savings of cutting directly. The choice of laser cutting technology “burning” determines the material. For example, black steel does not form oxides during processing or allows them to be easily removed. Aluminum alloys and stainless steel oxidize upon contact with O₂, therefore, when cutting these materials, the supply of oxygen is cut off by a stream of nitrogen.
  3. Evaporation – rarely used, in demand only when cutting thin-walled products or sheets of small thickness. The beam does not work with a continuous jet, but with short pulses, designed to melt and evaporate the metal without hitting anything around, for example, the substrate (in products). Air pressure removes technical debris from the work area. This technique requires much more heating of the material. For example, aluminum melts at 660 ํС and boils at 2519 ํС. Accordingly, you need almost four times more energy. The process is more expensive, therefore it is justified only in cases where other technologies cannot cope.

Thus, laser cutting by melting is the best value for money for most materials.

Metal Laser cutting equipment

Laser cutting devices are classified according to different parameters. According to the type of working environment – the source of laser radiation – there are three types of devices:

Solid state systems metal laser cutting equipment

The lighting module contains a solid working medium and a high-power gas-discharge lamp. The working body can be a rod made of ruby, neodymium glass and other materials. The edges of the rod are equipped with mirrors: translucent and reflective. The laser beam created by the working body gains power due to multiple reflections and goes out through a translucent mirror.

Gas devices. CO2 metal laser cutting equipemtn

Works in them (separately or in combination with helium and nitrogen). Carbon dioxide activates electrical discharges. To increase the power, a system of mirrors is also used.

Gas-dynamic metal laser cutting devices

Gas-dynamic devices have the highest power. The active substance is also carbon monoxide (CO₂), heated to a temperature in the range from 726 to 2726 °C. It is activated by an additional low power laser beam. Passing through a special nozzle, the gas changes state and becomes a source of radiation. This type of equipment is the most expensive.

The choice of the type of laser cutting machine depends on the material to be processed.

CNC metal laser cutting machines using carbon dioxide are excellent at welding, cutting, engraving metal, glass, plastic and other raw materials. Solid state type equipment is effective for cutting aluminum, copper, silver, brass. Do not work with non-metallic materials.

The quality of metal laser cutting. What does it depend on?

The quality of metal laser cutting is usually understood as accuracy, cut quality (minimum roughness, straight walls), speed of service delivery.

The result of the metal laser cutting work depends on many components:

  • Type and dimensions of the part;
  • Proper setup of laser cutting equipment;
  • Technical condition of the CNC machine;
  • Layout design quality.

To get the desired result, it is necessary to take into account all these parameters. Subject to the rules of use, laser cutters provide an accuracy of up to 0.1 mm.

The metal laser cutting speed is determined by the power of the equipment, the thickness and thermal conductivity of the material being processed. The higher the indicator, the faster the heat is removed from the working area, respectively, more energy is required. For example, a laser power of 600 watts is sufficient for cutting titanium or ferrous metals, but not enough for copper or aluminum.

Features of cutting individual metals

Individual material properties require the use of different metal laser cutting technologies. Alloys and non-ferrous metals are processed on machines with a power of at least 1 kW, for working with ferrous metals there will be enough power from 0.5 kW.

Carbon Steel

The cutting of high-carbon steels is carried out mainly by gas-laser technology using oxygen. Due to the strong thermal reaction in the area affected by the laser, the processing speed of the metal sheet increases.

This method gives a high quality cut. For curly cutting, for example, workpieces with sharp corners or holes, an inert gas is used in combination with a laser beam.

Stainless steel

When processing stainless steel products or sheets, nitrogen is used, which is transported to the working area under pressure up to twenty atmospheres. Given the high strength of raw materials, laser cutting is practically the only method of high-quality processing of stainless and galvanized steel.

Working with non-ferrous metals requires more powerful metal laser cutting devices, such as solid-state type.

Brass, aluminum and alloy

For interaction with brass, aluminum and alloys with its content, an inert gas is used under pressure up to ten atmospheres. The edges are of good quality, some burr formation is possible, which is easy to remove.

Copper has high thermal conductivity properties. The optimal sheet thickness for laser cutting is no more than 0.5 mm. Large thickness requires significant costs, which is not economically feasible.

Laser systems have proven themselves in cutting pipes up to 30 mm thick. The cutting line can be directed at any angle. The result is a flat surface, ready for further installation or welding.

An alternative to laser metal cutting

In modern metalworking, four metal cutting technologies are effectively used:

  • laser;
  • Plasma;
  • gas;
  • Waterjet.

Each method has its own advantages and disadvantages in relation to different types of materials.

Plasma cutting of metal

Plasma cutting is a metal cutting technology in which a plasma jet acts as a cutting tool. The advantages include the ability to work with any raw materials: non-ferrous, refractory and other complex metals. Another advantage of the technology is the creation of cuts of any shape, including complex geometric ones.

Plasma cutting loses a little to laser cutting as edges, respectively, and in accuracy. In laser processing, the edges have a greater degree of correspondence in perpendicularity.

For materials thicker than 6 mm, the plasma method takes less time and energy costs compared to the laser method. However, when working with thin materials and manufacturing parts of complex geometry, the use of a laser is more efficient due to greater accuracy and maximum compliance with the technical specifications.

 

Gas cutting of metal

The essence of the gas cutting process is as follows: acid gas or propane heats the material to be processed to 1000-1200⁰С, then oxygen is connected, which ignites upon contact with hot metal and cuts it. The technology is suitable for materials whose combustion temperature is lower than melting: for steels with a low and medium content of alloying elements. The advantages of the method are low cost, simplicity, equipment mobility. However, it is not suitable for all materials, cutting accuracy is much inferior to laser and plasma.

Water jet cutting of metal

The working tool for waterjet cutting is a mixture of water with abrasive particles (grains of silicon carbide, electrocorundum, other solids, garnet sand). Water enters the cutting head under pressure up to 6000 atmospheres, from there it breaks out at a speed of about 1000 m / s (and higher) into the chamber, where it mixes with the abrasive. The mixed jet destroys the integrity of the metal and washes away the cut off particles. An important feature of waterjet cutting is that the treated surfaces practically do not heat up, which gives the method a lot of undeniable advantages.

The technology has a number of advantages:

  • Work with any materials;
  • High cut quality due to the absence of burning and melting of the surface;
  • Possibility of processing heat-sensitive raw materials;
  • No harmful emissions in the working process;
  • Fire safety works.
  • The disadvantages include a lower speed in comparison with plasma and laser processing, high equipment cost and the cost of the process.

Hydroabrasive metal cutting

Of the options considered, laser cutting is the most versatile tool. In addition to direct cutting, devices are used for laser engraving of metal, marking, marking and other operations.

Practical application of laser cutting technology

The production of products using laser equipment consists of several stages:

  • Formation of the product idea.
  • Development of an artistic sketch.
  • Creation of a technical layout of the model.
  • Making a test part on a CNC machine.
  • Control parameters and refinement if necessary.
  • Start of mass production.

The creation of a technical layout should be given special attention, since the quality of the finished product will depend on its accuracy.

The metal laser cutting machines use the formats of AutoCAD, CorelDraw programs, so drawings for laser engraving or cutting must be made in these programs.

  • Requirements for layouts for laser cutting
  • Drawing scale 1:1.
  • Closed external and internal contours.
  • CIRCLE, LINE, ARC – commands for creating contours.
  • ELLIPSE, SPLINE commands are not supported.
  • When the lines overlap each other, the laser cutter will follow the same path several times.
  • The drawing for laser cutting should indicate the number of parts and work material.
  • All information about the drawing must be placed in one file.
  • Pricing in metal laser cutting services
  • The price of services depends on a number of components and varies depending on the terms of reference.

What affects the cost of laser metal cutting services

  • Type of metal. For example, cutting ferrous metals, steel and stainless steel costs 2-3 times cheaper than cutting copper, brass, titanium, aluminum and its alloys.
  • Sheet thickness. The greater the thickness, the higher the price. Non-standard technical tasks are calculated individually.
  • Complex shape details. The more cuts required to achieve the result, the higher the price.

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