Laser Welding Process History
Laser welding is a method of welding metal, which can design for a particularly precise connection of products. It will often use in the presence of a complex configuration of the contact of the elements that can weld. This technology is not used so often, but still, it has a lot of positive features.
With the help of it, you can get an aesthetic, smooth and smooth seam without deformed, curvatures. Welding can suitable for joining products make of stainless steel, aluminum, and even silver. Of course, these are not all the characteristic qualities of this type of welding, there are other features that deserve special attention.
- General characteristics
- Laser welding technology
- Advantages and disadvantages
- Conditions and methods of laser welding
- Types of lasers
- Application of hybrid installations
- Features of welding of thin-walled products
- Application of laser welding for glass and plastic products
- Models of laser welding machines
- How to make a laser cutter for a garage
- Possible seam defects
Laser welding of metals can perform using special equipment. This method appeared not so long ago, but it will manage to gain high popularity.
It can use in various fields of industry to create a strong all-in-one connection. This welding method has high accuracy, good performance and excellent connection quality.
Heating and melting in the working area occurs using a laser beam. The luminous flux generate can the laser is monochrome. All waves have the same length indicators.
This is what makes it much easier to control the flows, which will do for focusing lenses and deflecting prisms. The laser shows the phenomenon of wave resonance, which increases the starting power many times.
All these properties help to understand what laser welding is. During this technology, various welding machines can use – semi-automatic, automatic, and even robotic, which carry out work without the presence of a person. Each of them delivers a laser beam that heats and melts the selected area of the metal product.
The principle of operation of laser welding will base on the following properties:
- coherence. This indicator can base on the relationship of the phases of the thermal field of the laser beam in different zones;
- monochromaticity. This property will characterize a small width of the spectral lines that can emit to the source;
- orientation. During the welding process, the beam can not scatter when it moves from the source to the product being welded.
Thanks to these indicators, the power of the laser beam increases, it provides accurate measured melting and evaporation of metals in the welding zone.
The source can be at some distance from the welding zone, and the presence of a vacuum can not require in the area of the welding laser bath.
So how does laser welding work? When connecting products using a laser beam, the following processes can observe:
The elements that can prepare for connection can tightly connect to each other along the line of the future connection. Next, a laser beam will aim at the joint area.
The generator turns on. During this, the uniform heating, melting and evaporation of particles on the edges begins.
Due to the fact that the cross-section of the laser beam has a small size, the molten metal fills all the micro-dimensions and defects of products that fall within the range of the laser beam.
Important! Laser welding has a positive feature – during it, a welded joint with a high density is formed. But porosity and other defects that are inherent in other welding methods are absent during this technology.
Due to the fact that the laser beam moves along the connected surfaces at a high speed, metal oxidation does not occur during the welding process. With the help of the beam, you can make two types of seam – continuous and intermittent. Using the first option, stainless steel pipes can weld, where high tightness is required. The second type can use when welding small structures that have surface damage.
Advantages and disadvantages
The advantages of laser welding have made this technology popular and in demand. But it also, like other welding works, has negative aspects that must consider beforehand.
Among the advantages of welding, we can distinguish:
- Laser beam welding can use for a variety of materials-from metals and magnetic alloys to thermoplastics, glass, ceramics.
- There is a high accuracy and stability of the trajectory of the heating spot. Small size of the welded joint.
- This is what makes it invisible.
- There is no heating of the near-ear region. As a result, minimal deformation of the welded parts observe.
- During heating, no combustion products can form, X-ray radiation does not appear.
- High chemical purity of the welding process. This is due to the fact that additives, fluxes, and electrodes can not use during welding.
- It is suitable for welding in hard-to-reach places and can use at a great distance from the laser location zone.
- It can use for welding elements that are located behind transparent materials.
- Quick reconfiguration when switching to the manufacture of a new product.
- The welds are of high quality and strength.
Despite the fact that laser welding is a popular method that is excellent for repairing the car body, for working with various structures, metal products, it is still worth considering the pros and cons of the technology. As we understood, it has quite a lot of advantages, but do not forget about the disadvantages.
Special attention should be paid to the following negative qualities:
- laser welding equipment has a high cost. Also, accessories, spare parts are quite expensive. For this reason, this technology can use only in production facilities, enterprises. And some craftsmen resort to making laser welding with their own hands, but this requires some knowledge, and it is also necessary to have diagrams, drawings, instructions;
- laser-arc welding has a low efficiency index. For solid-state alloys, it is 1%, and for gas alloys it can be 10 %;
- dependence of the efficiency of the welding process on the reflectivity of the workpiece;
- high requirements for the qualification of service personnel;
- special requirements for the premises where the laser equipment is located. This applies to the indicators of vibration, humidity and dustiness.
Conditions and methods of laser welding
Laser welding of stainless steel, alloys and materials must be carried out in accordance with certain features. To get an increased beam power, its precise focusing is required.
At the moment when the beam intensity indicators become higher than the maximum value, it is passed through the central area of the front mirror and then through the system of guiding prisms to the working area.
Laser welding of stainless steel and other metals can be carried out at different locations of the products being welded.
The depth of penetration of the metal structure can be adjusted in a wide range – from surface to through. The working process can be carried out by a continuous beam or intermittent pulses.
Please note! Laser pulse welding is suitable for joining and processing products made of thin sheet metal. In addition, this technology can easily weld profiles with a complex design and parts with a large thickness.
It should bear in mind that laser welding of aluminum, copper, stainless steel, and other metals can carry out in several ways:
Butt method. It does not require additives, or flux. There may be a joint between metal products, but its size should not be more than 0.2 mm.
The same indicator will consider the limit for focusing the laser beam on the joint. The welding process carry out using a “dagger” penetration of metal surfaces to the entire thickness, while the intensity of laser radiation can observe up to 1 MW/cm2.
In these situations, the seam must protect from oxidation, argon or nitrogen is suitable for this. But helium will be able to prevent breakdowns of laser radiation.
The overlapping method. During welding, the sheets can superimpose on each other, their connection can make to powerful radiation.
During welding, local clamping of products is applied. The maximum gap between the surfaces of metal products during operation should be no more than 0.2 mm.
Types of lasers
Laser welding of aluminum alloys, copper, stainless steel and other metals, materials can carry out with different lasers. Devices can be solid-state and gas-type.
Each type can select according to the purpose of the equipment application. But at the same time, do not forget about the important characteristics of each species.
Laser welding of copper, aluminum, stainless steel, silver, plastic and even glass carry out with a solid-state laser. It requires the main component-a ruby rod, it can also make of glass with neodymium. Usually this element can locate inside the lighting chamber.
At the moment when light with a high power can supply to the chamber with a certain frequency, the excitation of atoms occurs in the crystal at this moment.
All this leads to the emission of light, which has waves with the same length. The end parts of the rod element consist of reflecting mirrors. One of them is partially transparent. Energy can release through it in the form of laser radiation.
It is worth noting! Solid-state lasers have a low power. This indicator can vary from 1 to 6 kW.
Gas-type lasers can consider more powerful and productive devices, in which a gas mixture acts as an active body. However, laser welding of titanium, copper, aluminum, and stainless steel, which can carry out using these devices, has important features:
The gas can pump from the cylinders by pump. For this purpose, a gas-discharge pipe can use.
An electric current discharge occurs between the electrodes, which causes an energetic excitation of the gas mixture.
In the end zones of the gas discharge pipe there are special mirrors through which laser beams can pass.
When performing laser welding of frames, car body and other products, the electrodes can connect to a power source. The cooling process of laser devices can carry out by a water system.
But still, gas devices have a significant drawback – large dimensions. But laser units with transverse gas pumping have small dimensions.
The total power indicators of the equipment start from 20 kW and higher. Thanks to this, metals with a thickness of up to 2 cm can weld at a speed of up to 60 meters per hour.
Laser welding of silver, copper, aluminum, titanium, stainless steel, and other metals can perform under atmospheric conditions. It requires a vacuum, but at the same time, there must the protection of the molten-metal from the influence of air.
Gases, usual argon, are used for this purpose. Due to the fact that there is high thermal power of the beam on the surface of the welded element, there can increase evaporation of the metal. The vapors can ionize, as a result of which the scattering and screening of the laser beam occur.
Laser welding of glass, plastics, and products makes of different metals, during which gas mixtures can use, can characterized to the fact that in addition to the protective gas, a plasma-suppressing gas penetrates into the welding area.
Helium can use as it, which is much lighter than argon, it will not scatter the laser beam. To simplify the process, many experienced welders often use combined gas mixtures that have plasma-suppressing and protective properties.
Features of gas-dynamic lasers
Gas-dynamic units have high power indicators. Carbon monoxide acts as the active body. It is heated to 3000 K and passed through the Laval nozzle. At the outlet of the nozzle, there is a rapid decrease in pressure and a gradual cooling of the gas mixture.
Application of hybrid installations
Laser welding of the car body, various structures with thick elements, and components with a gap can carry out using additional additive materials.
For these purposes, a wire feed can use, which ignites an electric arc. Thanks to this, the space between the plates can fill and a connection with high strength can create.
Important! When conducting laser welding of a car, or thick metal structures, the welding bath can protect by blowing with an inert gas, which can supply through a nozzle fix next to the laser head.
Laser welding of the body and other products with a high thickness can perform on a table or stands from the equipment. The process can carry out in several stages:
At the initial stage, the metal can clean of scale, oil stains, signs of water, and moisture.
Then the parts can tightly fit butt-to-butt.
Chemical etching of the surface of the metal product can perform.
Laser welding can configure with the require parameters depending on the type of metal weld.
Next, the head from the welding equipment can move to the start line of the connection, the welding start button can press.
During the welding process, it is necessary to constantly monitor the penetration of the beam into the joint area.
Features of welding of thin-walled products
The main advantage of laser welding is its variety. Suitable devices and devices can select for each type of work. But all when choosing them, it is worth relying on the type and features of the materials that will weld.
Usually, solid-state lasers and gas-based devices can use for thin-walled products. But all the first options can consider the most preferable.
Laser welding of small thicknesses can always perform using solid-state lasers. It is suitable for working with small products. Often these are microelectronic elements, for example, thin leads made of wire with a diameter of 0.01 to 0.1 mm.
Often, a solid-state installation performs spot laser welding using a solid-state laser device. But it is suitable for products made of foil structure with a point diameter of 0.5-0.9 mm. Using this method, a sealed cathode connection can make on the kinescopes of modern televisions.
The connection of small and thin-walled products can carry out at minimum power. If welding can perform in pulse mode, then it will be necessary to increase the pulse duty cycle and reduce its duration. But in continuous mode, it is necessary to increase the speed of the laser.
Application of laser welding for glass and plastic products
Laser welding of plastics and glass is performed using solid-state installations. They have a simple device – two electrodes can install in the reflecting tube, and in the space between them there is a mixture of ionizing gases.
Please note! Solid-state equipment is often used in the repair of glasses made of plastic and glass. It has become particularly popular when welding frames, this is due to the fact that this process does not require the use of solder.
Welding of plastic and glass products can perform in the same sequence as the connection of metal elements:
- the surfaces of the parts to weld can thoroughly clean of dust, stains, and various contaminants;
- then the installation and the electrode can prepare for subsequent work;
- the focusing lens can adjust. If a defocused lens can use, the laser beam will be blurred and it will not be possible to create a local melting of the metal. A properly focused beam should have a round shape;
- the required value of the welding power will set.
Models of laser welding machines
We have considered what laser welding of metal is and how it can carry out, but it is still necessary to know the models of devices that can use for its implementation. Mobile and compact type equipment can use for it.
The following laser devices are often used in industry:
Kvant-15 laser welding: The device is the most expensive and multifunctional. It can use in seam and spot welding technology for joining various metals and alloys with a penetration depth of up to 2-3 mm. It can also use for cutting tool, structural, high-alloy alloys.
LAT-s: This installation can use for laser welding and metal surfacing. It has high power and performance. The equipment can equip with coordinate tables, it is due to this that it is possible to process complex products.
MULE-1: This can small-size equipment that is used for laser welding and metal surfacing. With the help of it, soldering of silver and gold products can perform. The use of laser welding in jewelry makes it possible to easily weld with high accuracy. Even the connection of the frames of plastic glasses can allow.
Manual laser welding is carried out using devices:
WELD-WF: A portable device suitable for welding hard-to-reach places. Its device includes a manipulator that connects to the fiber. The power is 1.5 kW;
CLW120: Manual unit with low power. It is suitable for the jewelry field, which requires maximum precision. It can also use for spot laser welding. The power is 10 kW.
How to make a laser cutter for a garage
Many people can interest in how to do laser welding yourself. Since the equipment is quite expensive and not everyone can afford it, you can try to make a simple cutting machine using a laser yourself.
With it, it will be possible to cut a variety of patterns on strong steels, cut metal components or connect simple steel products.
For manufacturing, you will need a laser pointer. Additional components will also be needed:
- a flashlight that runs on batteries;
- an old DVD-ROM from which you will need to extract the matrix with a laser drive;
- soldering iron and screwdrivers for tightening.
At the initial stage, it is necessary to completely disassemble the drive of the old disk drive for the computer. It is from it that you need to remove the device.
Everything should do carefully, so as not to damage the main device. The disk drive must be a writing drive.
After the red diode can remove, it is he who burns the disk while recording information on it. With the help of a soldering iron, the diode fasteners can solder. This element is very sensitive, it does not need to throw.
Next, the laser pointer is analyzed, and how it is done can view on the video on the Internet. The diode from the pointer can replace with red light from the drive. The body part can make up a flashlight. And rechargeable batteries will need to power the laser cutter.
Possible seam defects
Laser welding tests can often carry out at production facilities, which allows for to prevent of possible seam defects. But still, even proper preparation does not always protect against deformations, non-cookers, and other unpleasant situations.
The following defects of laser welding are distinguished:
- Non-welding of the seam.
- Formation of pores and cracks.
- Swells, craters, welded shells.
- Extraneous inclusions.
These phenomena can form when the technology can not follow. The welder must always correctly set the settings in the equipment, depending on the metal to weld.
In addition, he must clearly control the process and monitor the movement of the laser beam along the welded area.
Laser welding technology is a popular method of joining different metals, as well as products made of glass, plastic and precious metals, which allows you to get a high-quality and strong connection.
But still, before starting it, it is necessary to carefully consider the important features, the principles of technology, on which the final result depends. In addition, in order for the process to carry out correctly, it is necessary to have experience and skills.
I’m Sahadat Hossain. I am working as Assistant Professor at Joynagor Technical and BM College. Besides, I have one welding workshop business from 2013. And in 2018 I started blogging about welding accessories. I want to share my experience with using welding accessories. In this blog, all content is written by me.