Another liquid state welding technology is electron beam welding. In such a case, the metal-to-metal connection is created while being liquid or molten. Because it joins two metal workpieces using the kinetic energy of electrons, the technique is sometimes known as welding. Karl-Heinz Steigerwald, a German scientist, created it. He developed the first functional EBW machine, which was put into use in 1958. The electron beam welding process is explained briefly in this article.
Electron Beam Welding
A welding technique based on the theory of electrons released in a vacuum tube or Braun tube is known as electron beam (light beam) welding. For applications ranging from thick to thin sheets and perhaps even in-depth welding, welding is carried out in a vacuum (high-vacuum welding). However, the range of applications has recently been expanded by the development of electron beam welding machines that can weld even in the absence of a complete vacuum (low-vacuum welding machine) or by shifting an electron gun (starting to move electron gun welding machine).
Fixed Electron Gun Vs. Moving Electron Gun
It is possible to install the electron gun within or outside the operating chamber to discharge the electron beam. With an electron gun positioned from outside of the processing chamber, external equipment is typically divided into two categories: fixed and moveable with a unique sliding seal. When using fixed electron guns, the base material is moved to alter the welding position. On the other hand, using movable electron gun devices, the welding location is altered by repositioning the electron gun. Devices with moving electron guns may weld in a variety of locations and have a rolling stroke of many meters.
Internal components include an electron gun that moves within the processing chamber placed on a robot that can simultaneously handle 5 coordinates (X, Y, Z, A, and C). These machines can weld in three dimensions, and some of them have a welding area that is at least ten meters. A low-power beam that is directed diagonally to the weld line scans the 3D weld location. A sensor integrated into an electron gun detects X-rays produced during welding to provide precise welding for grooves.
Electron Beam Welding Process
In EB welding, a high-velocity electron beam is directed towards the weld joint, often inside of a vacuum chamber. An electron gun is a high voltage power source that fuels an incandescent cathode, which then shoots out high-speed electrons. After that, the beam is accelerated and concentrated using a set of anodes and a concentrating coil, which focuses the beam using an electromagnetic field.
A deep, thin weld is produced by EBW, which has a beam that evaporates a hole into the workpiece material and a welding speed that is 10 to 100 times quicker than arc welding. Additionally, this causes extremely minimal distortion and small Heat Affected Zones (HAZ).
The components are typically moved beneath the electron beam by traditional rotational and linear motion systems, with programmable systems controlling power and weld speed. The location of the electron beam is typically fixed. Although there are many various types and configurations of electron-beam machinery, most of them operate in a similar way:
- The two components are properly cleaned to get rid of impurities and demagnetized if they are made of ferrous metals. Ideally, the contractor or welder should handle this.
- The components are fixed to their fittings and connected to the CNC-controlled work movement system of the welding machine. This may be programmed to move the components into place and make corrections as it goes.
- The vacuum pump is sealed, and a vacuum is produced by releasing the air within. For welding, certain materials, like titanium, need for a greater vacuum level.
- After the joint is aligned, the electron beam is created at the proper power. To ensure constant weld quality, beam settings may be physically or CNC changed throughout the cycle.
- The cycle of the e – beam welding is started.
- The vacuum pump is re-pressurized after welding is finished to enable opening and removal of the joined part.
- Fixtures are taken out, and the part is then put through a rigorous inspection procedure. Non-destructive The most popular quality assurance technique is fluorescent penetrant crack testing. This is frequently combined with radiography or visual inspection.
For better understanding, watch out this video:
Electron Beam Welding Requirements
There are a few fundamental requirements that must be met for electron welding to be effective:
- Stainless steel, titanium, various nickel and copper alloys, both high and low carbon steel, and other metals may all be joined together via EB welding. It may be used to effectively combine two different metals; however, when linked to other metal types with EB welding, refractory metals like aluminum and others produce varying outcomes.
- Since filler material is often not used in electron-beam welding, careful consideration should be given to the joint design. Both planetary and circumferential layouts characterize the finest joints. The majority of designs are suitable with EB welding, however, in order to achieve the closest abutment, it is crucial that the fit specifications of the joint be taken into consideration at the design stage.
- Since EBW is a machine-based technique, samples that are typical of the production component are often needed to establish and show weld outcomes. Then, these parameters may be applied to any future production needs.
Since not many welding procedures can weld steel that is, let’s say, 0.1 mm thick or, at the opposite extreme, 300 mm thick in a quick motion, the complete spectrum of electron beam welding fabrications is extraordinarily diversified. Here are some items that have been welded using an electron beam:
1. Bi-Metal Saw Blades
Electron beam welding is used to make a lot of bi-metal saw blades. The main portion of the blade, which is made of low carbon steel, has a small strip of high-speed steel that is needed for the cutting teeth that are electron beam welded to it. The bi-metal blade is much more flexible and less likely to break, which lowers the cost of materials. As a consequence, the product is more effective and less expensive.
2. Transmission Assemblies
Electron beam welding is widely used to create transmission assemblies. With significant material and machining cost reductions, complex items may be manufactured. The pieces may be finished machined and toughened before being put together by welding. This case illustrates how electron beam welding may limit distortion to a low degree, making it simple to fabricate parts that would otherwise be challenging or even unattainable.
3. Aerospace components
By using electron beam welding, titanium alloy aerospace components are created. Again, reduced distortion enables the precise joining of complex components. When welding such titanium alloys with an electron beam, there is little chance of oxygen pick-up and subsequent weld embrittlement since the vacuum welding atmosphere is so pure.
The strategy you must use when electron beam welding is greatly influenced by the metals you choose, the design process, joint preparation, and other elements. You can also read our article: Types of Welding Joints