Electron Beam Welding Technology
EB welding technology offers superior welding quality on a wide variety of components, from very small electronic devices up to turbine housings several inches thick, making it more versatile than conventional arc welding.
The advantage of Electron Beam Welding and Laser Welding is superior quality of welds compared to conventional arc welding. Laser & Electron Beam have much in common that differentiate them from conventional welding processes.
Electron Beam Welding (EBW) & Laser Beam Welding (LBW) both offer:
- Low heat input
- Fast welding speed
- Fast welding speed
- Narrow weld zone
- Small, localized Heat Affected Zone (HAZ)
- Highly controllable weld parameters
- Very wide power range for shallow or deep weld penetration
- Clean welds with no subsequent finishing required
Differences between EBW and LBW:
- EBW is performed in a high vacuum environment, which is particularly suited to titanium, refractory metals and flammable metals.
- LBW does not need a vacuum chamber, and is usually performed with a shielding gas such as argon or nitrogen. LBW equipment usually falls into two categories: below 1 KW and above 1 KW.
- An EB weld is usually narrower than the laser weld.
- The laser weld is particularly suited to high volume applications with shallow to medium penetration.
EBW emerged as a production process in the late 1950s within the aerospace and nuclear power generation industries. Since then, it has become a preferred technique for small precision parts requiring very high-quality welds in steel, stainless steel, titanium and other exotic alloys. Among the many applications for EBW are aerospace, automotive, defense, communications, electronics, jewelry, medical, oil and gas exploration, semi-conductor, sensors, transportation and commercial uses. The process has proved very reliable and cost-effective in high volume production due to the advent of small vacuum chamber machines and high welding speeds. LBW has some similar characteristics.
One advantage of EB and laser welding is the ability to weld in areas not accessible by conventional means, since the beam can be projected into difficult locations. For very limited access, EBW is required.
EBW is usually performed in a high vacuum to prevent dispersion of the electron beam and to eliminate all oxidization. As the electrons strike the work piece, their energy is converted into heat, instantly melting the metal. Since the electron beam is tightly focused, the effective heat input is much lower than that of traditional arc welding and therefore only minimally affects the surrounding material, with a small heat-affected zone.
Distortion is greatly reduced and the work piece cools rapidly. While normally an advantage, this can lead to cracking in high-carbon steel if precautions are not taken. Almost all metals can be EB welded, but the most common are stainless steels, super-alloys and reactive and refractory metals. The process is also widely used to perform welds on a variety of dissimilar metal combinations.
The amount of heat input—and thus the penetration—depends on several variables, most notably the number and speed of electrons impacting the work piece, the diameter of the electron beam and their travel speed. Greater beam current causes an increase in heat input and penetration, while higher travel speed decreases the amount of heat input and reduces penetration. The diameter of the beam can be varied by moving the focal point with respect to the work piece: focusing the beam below the surface increases the penetration, while placing the focal point above the surface increases the width of the weld.