ELECTRON BEAM WELDING OVERVIEW
We Dive into the process, benefits, applications, and more.
Electron Beam Welding (EBW) Process
The electron beam welding process is one of the most technologically advanced welding processes available. In general, the eb welding process uses electrons to heat up and weld metals together. An electron gun accelerates the electrons to a very high speed.
Then, a focuser narrows the electron beam to form a very powerful beam of electrons.
Next, the beam of electrons make impact with the work pieces. Consequently, the very high kinetic energy of the electrons is rapidly transferred into heat. Finally, the workpieces are welded together to form a solid part.
The whole process is performed under a vacuum in a chamber. This ensures there are minimal impurities from the air, and keeps the electron beam from dispersing. The result is a very high quality weld with great repeatability.
Electron Beam Welding Machine
- Electron Gun
- Power Supply/Controls
- Workpiece Fixturing and Controls
- Vacuum Chamber
The electron gun is responsible for generating the stream of electrons. The electron gun produces electrons by metal wire that is heated. At this point, there is not enough power to weld materials. The electrons must be accelerated and focused into a narrow beam. A high voltage power supply accelerates the beam of electrons. The high voltage system drives up the electron beam welding price considerably, due to its cost, and technical problems associated with high voltage systems. Finally, a focusing lens narrows the beam of electrons to form a high power density beam. Now, the beam can be applied for welding. As you can see, there is a lot going on in the electron gun.
As mentioned above, the power supply is one of the more expensive components of electron beam welding equipment. The power supply must be high voltage to accelerate the electrons fast enough to weld. The typical voltage range for electron beam welding equipment is 30kV to 150kV. The voltage can be either higher or lower depending on the conditions and desired weld depth. Weld depths can range from as small as 0.01mm to 250mm+. This is what makes the electron beam welding process so very capable.
The EBW welding process can never use people to move the work pieces. First, it is a vacuum process. They wouldn’t be able to breathe. Second, it is a very high voltage process and the risk for electrocution is very high. Third, the stream of electrons is very high energy, and as such emits strong X-rays. Obviously, this is no place for people to operate. Not even interns..
Consequently, this is a very automated process. Fixturing of the workpieces is setup on CNC tables. Once the tables are loaded with the workpieces, they are moved into the chamber computer controlled software. Likewise, the energy beam welding is also done through software.
Advantages of Electron Beam Welding
Electron beam welding has many unique benefits when compared to other welding methods. The eb welding process is very precise. There is such a high degree of control over the weld versus traditional welding processes.
Also, electron beam welding is very repeatable due to the controls and automation involved. Consequently, the quality and mechanical properties of an electron beam welded part are excellent.
One of the more attractive benefits is the ability to weld dissimilar metals together. For example, eb welding is used to weld aluminum to titanium alloys.
The electron beam welding process produces a small thermo-heat affected zone. This is advantages for welding thinner materials where warpage and deflection can be a concern.
Electron beam welding is done entirely in a vacuum chamber. This virtually eliminates all impurities and contamination during the process. Furthermore, any impurities occurring in the materials will vaporize.
The main drawback from eb welding is the possibility of cracking in the welds. This is due to excessive shrinkage from cooling down too fast.
Also, the cost of electron beam welding machines is substantially higher than other welding methods. Plus, the maintenance to keep the machine properly operating is higher too.
Applications of EB Welding
The industries most commonly implementing electron beam welding includes:
Aerospace and automotive use it for electron beam welding aluminum. Being capable of welding very thin features makes electron beam welding aluminum an attractive solution for those industries.
Electronic components use low energy beam welding. They mostly weld micro components and low energy beam welding excels in this regard.
Conversely, oil and gas industries use high energy eb welding to join very thick metal joints together. Electron beam welding excels in this application with its high speed and repeatability.