Electron Beam vs Laser Welding

Electron Beam Welding vs Laser Beam Welding

When comparing electron beam welding (EBW) vs laser welding (LW), it is important to note that both processes fall under a general heading of power beam welding.

 

The difference between laser beam welding and electron beam welding

Electron beam welding uses a finely focused stream or beam of electrons, whereas lasers use monochromatic coherent light, photons. In both cases, the energy of the electrons or photons is turned into heat energy when they impinge upon the surface of the metal.

Electron beam welding is lesser-known than laser welding out of the two techniques. This is not because it is an inferior process to laser, but mostly due to people’s perceptions. Most have heard about or have seen Star Wars, James Bond, and a host of other hi-tech sci-fi films that have bombarded our screens over many years and coupled with the high profile many respected institutions have been putting forward, unfortunately, the electron beam process has taken a back seat.

The following article examines some of the differences between electron beam welding in a vacuum vs laser welding with a shielding gas.

 

Vacuum Environment

Electron beam welding in a vacuum aids the weld quality, as it tends to pull contamination away from the weld pool. Welding in a vacuum also results in the operator not becoming exposed to the hazardous welding environment.

Conventional laser welds at atmospheric pressure, with an additional shielding gas. However, you can laser weld in a vacuum, which significantly increases the depth of the weld.

 

Shielding Gas

Shielding gas is not required for electron beam welding as the process is done in either low or high vacuum.

Laser welding in a normal atmosphere requires a shielding gas; it is an expensive, but essential, consumable. Fume extraction may also be an issue.

 

Component Size

Electron beam welding in a vacuum places restrictions on component size, as it must fit inside the vacuum chamber. Chamber volumes are kept to a minimum to reduce evacuation times.

Laser welding with a shielding gas can accommodate any component size, as there is no vacuum chamber. Furthermore, fibre optic delivery systems can be used. This allows the welding head to be remote from the power source.

 

Welding Speed

Electron beam welding can achieve deep penetration welds over a wide range of speeds, whereas laser welding with a shielding gas requires high welding speeds due to the plume of metal vapour that forms.

 

Weld Quality

Electron beam welding produces high-quality welds in a wide variety due to the inert atmosphere, which creates a very stable and repeatable environment. Joint finding and imaging using backscattered electrons are advanced options that can further increase the weld quality.

Laser welding needs a shielding gas, typically nitrogen or argon, to prevent oxidisation of the weld area and stability of the weld pool. Real-time monitoring of weld depth and quality are expensive options, but they can improve weld quality.

 

Single Pass Welding of Thick Sections

Electron beam welding in a vacuum can achieve 20mm penetration in stainless steel when using 6kW beam power at 60kV. Up to 300mm thicknesses can be welded in a single pass.

Laser welding with shielding gas can achieve approximately 1kW per mm depth of weld in steel. However, limited availability and high cost of high-power laser systems is a factor.

 

Automated Process

Electron beam welding can be highly automated with the evacuation time of the chamber in a few seconds. 40 seconds per components is a typical cycle time within the automotive industry, but time is dependent upon the length and complexity of the weld.

Laser welding can also be highly automated with high production rates, in addition to there being no waiting time for chamber evacuation. Beam splitting and beam sharing are also possible.

 

Wearing Components

The main wearing component within the electron beam welding process is the filament. Metal vapours can deposit on the viewing prism, but this has no effect on weld characteristics and the prism can be cleaned.

During the laser welding process, optical devices such as mirrors and lenses can be coated by a metal vapour that is produced during welding, leading to a drop in beam power.

 

Power Efficiency

Electron beam welding is a very efficient process, typically converting 85% of electrical power.

Laser welding typically converts up to 40%, when using modern fibre and disc lasers.

 

Cost Comparison

Electron beam welding is more expensive than tungsten inert gas (TIG) and metal inert gas (MIG) welding.

Laser welding is also more expensive than TIG and MIG, with prices increasing steeply with increasing power.

 

Turnkey Solutions

Electron beam systems include a chamber, fully automatic vacuum system, work handling, and control system.

Laser welding usually requires a systems integrator to provide an integrated solution, as the laser source does not include a control system or work manipulation.

 

 

The best process to use is often dependent on the given application. If you are not sure which system is right for your application, please get in touch! Our machines are built-to-order and manufactured at our Cambridge Headquarters. With 60-years of process know-how in providing turn-key solutions, we can find the right solution for your application.

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