In this article, we shall learn about electron beam welding its diagram, working, applications, advantages, and disadvantages. We have also provided a PDF for the same
This Welding Process was first developed in 1949 by Karl-Heinz Steigerwald who was a German physicist. In this article first, we will see the Definition, how it Works, Applications, Advantages, and Limitations of EBW Machine as well.
What is Electron Beam Welding?
Electron Beam Welding is a liquid state welding process in which two similar or dissimilar metals are joined by the use of heat and that heat is generated by high energy electrons. When an electron strikes with a high speed to the workpiece there are two forms of energy conversion that take place namely kinetic energy and thermal energy.
Construction of Electron Beam Welding Machine:
Electron Beam Welding Machine consists of the following parts:
- High Voltage Power Supply
- Electron Gun
- Cathode Grid
- Optical Viewing System
- Magnetic Lens
- Deflecting Coil
- Vacuum chamber
- Workpiece Holding Device
Let us discuss each part in detail.
High Voltage Power Supply:
The Power supply is categorized into two ways one is low, and the other is high voltage.
- Low voltage range of the thin welding is between 5 to 30 kV.
- High voltage range for thick welding is between 70 to 150 kV.
In electron gun, the free electrons are generated by means of thermo-emission from a hot metal strap or wire. The main purpose of the electron gun is to convert free electrons into an electron beam with the help of cathode grid, anode, magnetic lens, and deflection coil.
By this part, the free electrons are generated. However the voltage of generated free electrons is very low. To accelerate this free electrons, they are passed through high electric field which is produced by Anode and emitter (Cathode).
The anode is used to accelerate the electrons which are generated by the cathode grid.
Optical Viewing System:
Optical viewing system helps us to determine and set up the point of action where the electron beam is impacted on the workpiece.
Magnetic lenses allow only the converging electrons to pass. It absorbs the low energy of divergent electrons and It provides a high intense electron beam.
- The deflection coil is a type of magnetic lens and It is used in cathode ray tubes.
- It helps to scan the electron beam all over the screen.
- In the vacuum chamber, there is no presence of air. The welding in this machine takes place in a vacuum.
- The pressure presets here is below or at the atmospheric pressure.
- It is also known as the Braun tube or chamber.
- The workpiece is attached to the fixtures.
- The workpiece can be of similar or dissimilar metals.
Workpiece Holding Device:
- The workpiece holding device is also called as Fixtures. It is used to hold the workpiece rigidly.
- The fixtures are made up of steel castings, stainless steel, cast iron, high tensile steel, and so on.
Working Principle Electron Beam Welding:
The working principle of electron welding is the same as electron beam machining. Here we use to join similar metals or dissimilar metals with the help of the beam of electrons.
First we supply the power to the system. There is a cathode [negative charge] attached which is made up of Tungsten. And just below it, the anode is connected.
Now we have to create a potential difference around 30 to 175 kV because when the coherent light produces from the cathodes which pass through the anodes and that anodes help to accelerate it as much as It can.
Now the coherent light appears directly to the workpiece, meanwhile focusing coil is attached which decrease the extra gap between the coherent light.
Now the light directly comes at the workpiece with the help of a deflection coil and here temperature is so high that it melts the workpiece. The kinetic energy is now converted into thermal energy.
The workpiece is attached to the fixtures here and the whole process is done in a vacuum which means there is no air. If air is allowed, the direction of coherent lights may get deflected and it may appear in some other place that we do not want to weld.
Video of Modern Electron Beam Welding Machine:
Applications of Electron Beam Welding:
Electron Welding has wide range of applications. Following are some of them:
- It is used for welding and drilling the workpiece.
- Electron beam welding is used for various industries like Marine, Automobile, Aircraft, Manufacturing, etc.
- It is also used in the defence sector for making various products.
- It is for joining two similar or dissimilar metals.
- For joining of refractory material and those are tungsten, ceramics, and so on.
- It also used in the medical industries.
- The electron welding cuts the narrow slots 25-micron meter.
Advantages of Electron Beam Welding:
So here are some advantages of Electron beam Welding:
- There is no requirement for filler material in electron welding.
- There is very little distortion.
- The welding defects appear also very less.
- Electron welding also welds the hard material.
- The surface finish obtained in this process is high.
- It also provides a high metal joining rate.
- The heat effective zone and welding are narrow.
- This process also helps to join uniform and diffusion metals.
- The welding process is continuous and tight.
- The workpiece has high strength properties and maintains up to 95% of the strength of the base materials.
- This beam welding process is very precise.
- The welding process is fully automated.
Disadvantages of Electron Beam Welding:
The disadvantages of Electron Beam Welding are following:
- The process can not be done by a semi-skilled worker so it requires a high skilled worker that means the person must have knowledge of the electron welding process.
- The workpiece size is not big, it is limited because of the vacuum chamber.
- High maintenance is required.
- The electron welding equipment is costly.
- The Installation and Capital cost is high.
- The electron welding has x-ray radiation and that is a major problem for human.
- The production expenses are also high.
- All the images of this article are made by Saubhik Roy- Design team LM.
- Feature Image is modified by the author.
- Video by: Ústav přístrojové techniky v.v.i. ISI Brno