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Electron Beam Welding: Narrow Weld Seams & Reliable Joints
Description
Description
The electron beam technology is used for creating extremely reliable, deep and at the same time narrow and parallel weld seams. Angle distortion, transverse shrinkage and other disturbing influences occurring during welding of delicate component are minimal.
Application possibilities
The application spectrum of this method ranges from welding of very fine films to joining of workpieces having a section thickness of more than 100 mm in only one operation. Almost the entire spectrum of metal-based materials and many combinations of such materials can be welded.
Additional benefit
There is a great cost savings potential in the design of mechanical components due to alternative component layouts. The high welding speed of the electron beam technology allows for a high productivity in large-series production in electrical and automotive engineering. For the processing of individual components and small series, e.g. for aerospace industry, shipbuilding or rail engineering electron beams have the advantages of being precise and repeatable since they are based on electronic measured and controlled variables as well as on control factors, which offer optimal conditions for automated production processes.
Benefit from our strengths:
Safe welding technology, efficiency, reliability.
Application possibilities
The application spectrum of this method ranges from welding of very fine films to joining of workpieces having a section thickness of more than 100 mm in only one operation. Almost the entire spectrum of metal-based materials and many combinations of such materials can be welded.
Additional benefit
There is a great cost savings potential in the design of mechanical components due to alternative component layouts. The high welding speed of the electron beam technology allows for a high productivity in large-series production in electrical and automotive engineering. For the processing of individual components and small series, e.g. for aerospace industry, shipbuilding or rail engineering electron beams have the advantages of being precise and repeatable since they are based on electronic measured and controlled variables as well as on control factors, which offer optimal conditions for automated production processes.
Benefit from our strengths:
Safe welding technology, efficiency, reliability.
Application Areas
Application Areas
Electron beam technology is used in almost all industries and for the solution of both standardized and technically demanding welding tasks.
Automotive industry: large quantities at high efficiency e.g. the complete power train (engine, drive) (figure 1).
Aerospace engineering: challenging special applications, such as helicopter components (figure 2) or satellite tanks.
Power & electrical engineering: large quantities based on materials such as copper and other contact materials e.g. power switching (figure 3).
Rail, ship and medical engineering: safe join connections, e.g. coupler on the ICE train (figure 4) and joining of implants (figure 5).
Mechanical engineering and food industry: small and medium quantities based on a broad range of high-grade steels and the combination of which. Here, components with a weight of up to 50 t can be welded by using the electron beam technology.
Research and Development: Challenging tasks with special materials ranging from tungsten to platinum are implemented in complex designs.
Automotive industry: large quantities at high efficiency e.g. the complete power train (engine, drive) (figure 1).
Aerospace engineering: challenging special applications, such as helicopter components (figure 2) or satellite tanks.
Power & electrical engineering: large quantities based on materials such as copper and other contact materials e.g. power switching (figure 3).
Rail, ship and medical engineering: safe join connections, e.g. coupler on the ICE train (figure 4) and joining of implants (figure 5).
Mechanical engineering and food industry: small and medium quantities based on a broad range of high-grade steels and the combination of which. Here, components with a weight of up to 50 t can be welded by using the electron beam technology.
Research and Development: Challenging tasks with special materials ranging from tungsten to platinum are implemented in complex designs.
Process
Process
The energy needed for the electron beam welding process (high voltage of 60–150 kV) is supplied by accelerated electrons. Beams are always generated in the vacuum. Mostly, the welding process is performed in the vacuum, but in some cases also on the atmosphere. When the electrons collide with the workpiece a large part of their kinetic energy is transformed into heat.
The energy density in the focal spot diameter ranges from less than 0.1 mm to 2 mm in the range of 105 to 109 W/cm2. Electron beam welding offers approximately the same power flux density like laser beam welding but it has a considerably higher efficiency (laser: 3–14 %, electron beams: approx. 70 %). This method allows for high welding speeds and for extremely deep and narrow weld seams. Due to the small seam width distortion can be kept very low. Electron beam welding is used for creating small weld seams since the electron beam can be deflected precisely by the applied electric fields. The weld seam depth spectrum ranges from 0.3 mm to 300 mm (aluminium); 150 mm (steel). The high energy density allows for welding all metals – also highly melting metals – as well as for the creation of mixtures by welding different materials, e.g. steel and bronze.
Electron beam welding systems are often used in the mass production of gearbox components in the automotive industry (particularly in Japan and Germany). Besides simple and well-priced commission orders, components for aerospace industry, railway transportation and food industry are welded by using the electron beam technology.
When penetrating into the material the electrons are decelerated and the largest part of their kinetic energy is transformed into heat.
The deep-penetration effect is created as follows:
One electron after the other collides with the workpiece surface and heats it spot-wise. At energy densities of more than approx. 106 W/cm2 the melted material will vaporize in the centre of the so-called focal spot. A vapor capillary is created, which is surrounded by liquid material. It allows the beam to penetrate deeper and to melt solid material again. If the workpiece is moved relative to the beam, the material in front of the beam will be melted. It flows around the vapor capillary and solidifies on the back of the capillary. .
The deep-penetration effect allows for creating narrow weld seams having a depth of more than 100 mm (figure: deep welding in aluminium (150 mm)). An aspect ratio of depth to width of the weld seam of up to 50:1 can be achieved. 
The high energy density allows for welding all metals – also highly melting metals – as well as for the creation of mixtures by welding different materials, e.g. steel and bronze (figure: typical deep welding in bronze/steel (20 mm)).
Thus, by using the electron beam technology pro-beam is able to join aluminium pressure die castings in a safe manner. Rests of releasing agents that may be locked in the material as gas can slowly escape without causing the dreaded explosive expansion of the gases. The formation of hot cracks in high strength nickel alloys can often be controlled by heating in a systematic offset manner. 
The application of the pro-beam multi beam technology allows for producing up to sixty weld seams simultaneously by using only one electron beam. The axial weld on a synchronizing gear is produced by using three beams (figure: three-beam technology for welding a synchronizing gear).
This method minimizes the distortion and reduces the welding time by two-thirds. Furthermore, expensive clamping technology and tack welding are not necessary. In this example, the deviations from true running and axial run-out are less than five-hundredth millimeter.
The energy density in the focal spot diameter ranges from less than 0.1 mm to 2 mm in the range of 105 to 109 W/cm2. Electron beam welding offers approximately the same power flux density like laser beam welding but it has a considerably higher efficiency (laser: 3–14 %, electron beams: approx. 70 %). This method allows for high welding speeds and for extremely deep and narrow weld seams. Due to the small seam width distortion can be kept very low. Electron beam welding is used for creating small weld seams since the electron beam can be deflected precisely by the applied electric fields. The weld seam depth spectrum ranges from 0.3 mm to 300 mm (aluminium); 150 mm (steel). The high energy density allows for welding all metals – also highly melting metals – as well as for the creation of mixtures by welding different materials, e.g. steel and bronze.
Electron beam welding systems are often used in the mass production of gearbox components in the automotive industry (particularly in Japan and Germany). Besides simple and well-priced commission orders, components for aerospace industry, railway transportation and food industry are welded by using the electron beam technology.
Further information
Deep-penetration effect
When penetrating into the material the electrons are decelerated and the largest part of their kinetic energy is transformed into heat. The deep-penetration effect is created as follows:
One electron after the other collides with the workpiece surface and heats it spot-wise. At energy densities of more than approx. 106 W/cm2 the melted material will vaporize in the centre of the so-called focal spot. A vapor capillary is created, which is surrounded by liquid material. It allows the beam to penetrate deeper and to melt solid material again. If the workpiece is moved relative to the beam, the material in front of the beam will be melted. It flows around the vapor capillary and solidifies on the back of the capillary. .
The deep-penetration effect allows for creating narrow weld seams having a depth of more than 100 mm (figure: deep welding in aluminium (150 mm)). An aspect ratio of depth to width of the weld seam of up to 50:1 can be achieved.
Process parameters
The electron beam can be controlled precisely. All process parameters can be measured and controlled directly and as electric variables. The measurement of electric currents is easier than the measurement of light and optical variables. Innovative deflection methods and fast CNC control systems offer new possibilities for material processing.
The precise adjustment possibility is the advantage of all electron beam applications:
The precise adjustment possibility is the advantage of all electron beam applications: By simple and reliable measurements all setting parameters of the beam it can be exactly recorded and easily reproduced. A direct feedback to the control loop is possible. Thus, the electron beam can be oriented to the area being worked on both manually and automatically. It is easy to handle as well.
The precise adjustment possibility is the advantage of all electron beam applications:
The precise adjustment possibility is the advantage of all electron beam applications: By simple and reliable measurements all setting parameters of the beam it can be exactly recorded and easily reproduced. A direct feedback to the control loop is possible. Thus, the electron beam can be oriented to the area being worked on both manually and automatically. It is easy to handle as well.
Permissible gap
The maximum permissible gap width ranges between one to five percent of the welding depth, however, it is maximum 0.3 mm. Variations from this values must be checked for the concrete application case. In case of welding larger gaps, there will be a reduced weld seam quality (weld depression) or filler material must be used. With regard to technical and commercial aspects, both cases are not wanted.
Design
The electron beam technology opens up to designers new possibilities for coping with joining problems. The optimization of the materials used allows for the application of cost-efficient production processes because working with the electron beam does not only guarantee little distortion and highest precision.
The application of the electron beam in the multiple beam process also overcomes the limitations of other welding methods:
In the welding process the electron beam will have an advantage over the laser if production must be performed within narrow tolerances, if the workpiece must not become too hot or very large welding depths are required. Since it is possible to join many workpieces from individual components, expensive materials can often be replaced by more economic ones. Thus, an intelligent welded design can redundantize expensive chipping or eroding processes.
The application of the electron beam in the multiple beam process also overcomes the limitations of other welding methods:
In the welding process the electron beam will have an advantage over the laser if production must be performed within narrow tolerances, if the workpiece must not become too hot or very large welding depths are required. Since it is possible to join many workpieces from individual components, expensive materials can often be replaced by more economic ones. Thus, an intelligent welded design can redundantize expensive chipping or eroding processes.
Materials
The high energy density allows for welding all metals – also highly melting metals – as well as for the creation of mixtures by welding different materials, e.g. steel and bronze (figure: typical deep welding in bronze/steel (20 mm)).Thus, by using the electron beam technology pro-beam is able to join aluminium pressure die castings in a safe manner. Rests of releasing agents that may be locked in the material as gas can slowly escape without causing the dreaded explosive expansion of the gases. The formation of hot cracks in high strength nickel alloys can often be controlled by heating in a systematic offset manner.
Multi beam techology
The application of the pro-beam multi beam technology allows for producing up to sixty weld seams simultaneously by using only one electron beam. The axial weld on a synchronizing gear is produced by using three beams (figure: three-beam technology for welding a synchronizing gear).This method minimizes the distortion and reduces the welding time by two-thirds. Furthermore, expensive clamping technology and tack welding are not necessary. In this example, the deviations from true running and axial run-out are less than five-hundredth millimeter.
Downloads
Downloads
Quality Assurance
Quality Assurance
Due to the fact that all important parameters are based on electrical control variables the electron beam is able to measure and to control its processes in a precise manner. Today modern electron beam machines can monitor and control their beam quality themselves.
The accurate positioning of the beam by means of electron optical joint recognition – as the most important link to the component – is performed automatically. Complex secondary processes, such as preheating of the joining area, can be carried out by the beam. Thus, they can be fully integrated into the CNC cycle.
Process control for certain types of defects has already been tested. However, the focus is still on the conventional recording of parameters in the process documentation.
In addition, the electron optics can be used for analyzing the position and the properties of the weld bead.
Today, more and more components are labeled for documentation purposes. This labeling is performed with the same beam that has previously created the weld seam.