At that time, it was used mainly in the aerospace and nuclear industries. Since then, it has become the welding technique with the widest range of applications.
This has resulted from the ability to use the very high energy density of the beam to weld parts ranging in sizes from very delicate small components using just a few watts of power, to welding steel at a thickness of 10 to 12 inches with Kilowatts or more.
Two welding modes are used in the EBW : 1-Conductance mode: Mainly applicable to thin materials, heating of the weld joint to melting temperature is quickly generated at or below the materials surface followed by thermal conductance throughout the joint for complete or partial penetration. The resulting weld is very narrow for two reasons: a- It is produced by a focused beam spot with energy densities concentrated into a. This is possible since the concentrated energy and velocity of the electrons of the focused beam are capable of subsurface penetration.
The subsurface penetration causes the rapid vaporization of the material thus causing a hole to be drilled through the material. In the hole cavity the rapid vaporization and sputtering causes a pressure to develop thereby suspending the liquidus material against the cavity walls.
As the hole is advanced along the weld joint by motion of the workpiece the molten layer flows around the beam energy to fill the hole and coalesce to produce a fusion weld. The hole and trailing solidifying metal resemble the shape of an old fashion keyhole. Both the conductance and keyhole welding modes share physical features such as narrow welds and minimal heat affected zone.
The basic difference is that a keyhole weld is a full penetration weld and a conductance weld usually carries a molten puddle and penetrates by virtue of conduction of thermal energy. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next.
What is Scribd? Explore Ebooks. Bestsellers Editors' Picks All Ebooks. Virtually all metals can be welded with an electron beam. Of course, the quality of welds depends on the metallurgy as well as other technical criteria, such as welding parameters and joint design.
Filler material is not typically used to join the majority of components hence the metallurgy does not change. This makes the electron beam welding process simple and more cost effective. As with any rule, there are exceptions. There are materials where it is advantageous to use filler metals, e. The use of series aluminum filler wire changes the metallurgy and prevents cracking. It is beyond the scope of this paper to detail the weldability of various metals; therefore, the following examples will focus on certain production applications.
Low to medium carbon micro-alloyed steels are typically used for manual transmission gear components in the automotive industry Figure 6. Some of these materials are more prone to develop cracks after welding due to the significant hardness increases in the HAZ. These are caused by the quenching effect after welding and can be influenced by the width of the weld and the welding speed. Preheating the components is a common remedy used to substantially reduce hardness increases.
It has become common practice in the automotive industry to preheat gears prior to welding in order to reduce the quenching effect in the HAZ. A welcome side effect of preheating in mass production is that welding speeds can be safely increased, making the process more economical.
Welding of automatic transmission components is yet another application used by the automotive industry. The range of components to be welded typically includes a variety of designs for shaft assemblies as well as planet carriers. The materials range from low carbon sheet metal for clutch carriers to medium carbon, micro alloyed steels for shafts.
The molten low and medium carbon materials mix together without posing any problems. Light and medium duty planet carriers are made of low carbon steel sheet metal. This material is perfectly weldable; the challenge lies in the design of these parts which have 3 to 5 segments that need to be joined. The specification of these segmented welds typically does not allow for substantial underfill of material either at the beginning or at the end of the joint Figure 7.
The combination of deflection pattern and continuous adjustment of the beam power helps to mitigate this underfill thereby optimizing the joint quality to meet the specification. A challenge greater than the sheet metal design is posed by joint segments with varying thicknesses that require a change of power not only at the beginning and the end of the joint but also in between.
Again, a deflection pattern in combination with a continuous adjustment to beam power permits the development of a robust set of welding parameters that hold up in daily production on the manufacturing floor.
The use of stainless steel is very common in the industry because of its corrosion resistance to many substances, gas or liquid, which contact its surface. Most grades of stainless steels can be easily welded with the electron beam and most importantly, the welds are corrosion resistant as the parent material. As an example, plates with complicated cooling channels for the processing industry require weld penetrations of up to 0. The 2-dimensional weld pattern shown in Figure 8, has total weld length of up to inches which introduces a high amount of heat into the plate.
Narrow welds for a limited heat input minimize and keep the amount of distortion at a technically acceptable level and are therefore critical to this application. Titanium alloys are widely used in the aircraft industry for their high strength-to-weight ratio and their corrosion resistance.
The electron beam welding process is widely used in this industry to join new and to repair used components. Narrow welds for a limited heat input minimize and adjustment of beam power helps to mitigate this underfill keep the amount of distortion at a technically acceptable thereby optimizing the joint quality to meet the level and are therefore critical to this application.
Advanced designs of heavy duty planet Titanium alloys are widely used in the aircraft industry for their high strength-to-weight ratio and their corrosion resistance. The electron beam welding process is widely used in this industry to join new and to repair used components.
Other fields of applications for Titanium materials are, for example, medical implants for which pure titanium is preferred over its alloys.
The pins of the implant, shown in Figure 9, need to be welded into the base plate. The electron beam hits the pins from the flat back of the plate which gets machined after the welding.
For these small pin diameters it is advantageous to deflect and move the beam in circles electronically rather than mechanically.
The welds are staggered to equalize the heat distribution in Figure 7: Planet Carrier with Shaft for Automatic the base plate.
Critical to this application is a partial, Transmission constant weld penetration to prevent a breakthrough of the beam and keep the front of the implant absolutely vapor carriers are forged of micro alloyed steels containing about and splatter free.
A challenge greater than the sheet metal design is posed by joint segments with Cross section: varying thicknesses that require a change of power not only Backside Machined at the beginning and the end of the joint but also in after Welding between. Again, a deflection pattern in combination with a continuous adjustment to beam power permits the development of a robust set of welding parameters that hold up in daily production on the manufacturing floor.
The use of stainless steels is very common in the industry because of its corrosion resistance to many substances, gas or liquid, which contact its surface. Most grades of stainless Backside of Implant before welding steels can be easily welded with the electron beam and most importantly, the welds are as corrosion resistant as the parent material.
As an example, plates with complicated Figure 9: Medical Implant. What types of Electron Beam Welders are being used?
Manufacturing cost and quality are key goals to consider in the fabrication of components. Each industry applies its own criteria to reach these goals. From a machine tool vendors point of view these goals translate into different machine designs, such as welders for low to medium 0. This type of welder typically employs a 2-station dial index with one part in cooling channels for the processing industry require weld each of the stations.
To further optimize productivity, the penetrations of up to 0. A more advanced design incorporates a drawer style increased, depending on their size Figure A further chamber which allows the tooling including parts to be reduction in cycle times to this production machine has entirely removed from the chamber for easier loading and been achieved through a design change that integrates a unloading of assemblies and tooling changes Figure The absolute shortest cycle times can be achieved with the so-called nonvacuum electron beam welder which welds parts in atmospheric pressure.
This technology produces welds that are wider than those. Figure Small Chamber Welder. These welders come in all sizes with vacuum chamber volumes ranging from about 1 m3 to more than m3. The electron beam gun is located either inside the vacuum chamber or stationary on the outside Figure Figure Production Welder with Load Lock Chamber One commonality of these electron beam welders is that all Medium volume production is typically performed in beam parameters and all mechanical axes are numerically chamber machines with specialized tooling.
As with any modern majority of applications need axial or circumferential machine tool, all process parameters can be stored by their welds, multiple part holders should be used whenever respective part numbers and retrieved at a later date. In possible in order to make the process more cost effective. This machine welds. EB welding technology has reached new heights, but development is still ongoing. It centers on improvements to the electromagnetic focus and deflection system to shorten their response times.
Today, fast beam deflection systems allow for electronic imaging of the assembly around the joint area or splitting of the electron beam to weld 3 or 4 spots at virtually the same time. Ongoing developments seek to combine various processes, such as welding with 3 beams while simultaneously preheating the joint area in front of the weld pools with 3 additional beams.
Summary Electron beam technology has advanced for decades reaching its current highest level. Eb welders have matured to meet the demands of modern industries such as the low volume, high quality aircraft industry, as well as mass production-oriented automotive industry. Different types of electron beam welders have evolved over the years influenced by the market to address specific needs from both a technical and economical perspective. In all these applications the process proved to be robust and flexible at the same time.
All grades of steel can be welded, as well as low melting alloys such as aluminum and magnesium, and high melting materials such as Nickel- and Cobalt-based alloys. The pattern generator, unique to the eb welding process, has proven to be very powerful in stabilizing the key hole to. Your email address will not be published. Save my name and email in this browser for the next time I comment. This site uses Akismet to reduce spam.
Learn how your comment data is processed. Introduction to Pressure Vessels Vessels, tanks, and pipelines that carry, store, or receive fluids are called pressure vessels.
A pressure vessel is defined as a container with a pressure Knuckle Joint A knuckle joint is used to connect two rods which are under the action of tensile loads. However, if the joint is guided, the rods may support a compressive load. A knuckle joint Skip to content Home - Blog - Fabrication Guide. Table of Contents. Leave a Reply Cancel reply Your email address will not be published.
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