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Electron Beam Welding (EBW) Explained

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Electron beam welding is a process that utilises the heat from a high-velocity electron beam to form a weld. An electron gun generates the beam through the use of magnetic fields. The kinetic energy from electrons is converted to heat upon contact, thus melting the workpiece and creating a joint.

Let’s cover some key points that make electron beam welding stand out from other welding methods.

What Is Electron Beam Welding?




Electron Beam Welding

Electron beam welding (EBW) uses a high-velocity beam of electrons to melt and fuse metals together. The electron beam can be focused to create a small weld area, which makes it ideal for welding delicate parts or complex designs.  On top of that, EBW works at a rapid rate, making it one of the fastest processes in assembly welding.

Electron beam welding machines are quite complicated, requiring skilled operators to achieve optimal results. On the other hand, it offers a wide range of penetration depth, generally from 0.127 mm to 50 mm/0.005 to 2 inches (although much higher depth can be achieved for certain materials) when using a filler material with the latter, making it stand out compared to common welding techniques like MIG, TIG, and stick welding. EBW fusion welding process run on a single pass creates joints with minimal distortion and possesses the ability to join different metals.

Electron Beam Welding Process

The working principle behind electron beam welding is emitting a focused beam of high-velocity electrons into a joint. This process is usually performed inside a vacuum chamber to improve efficiency and prevent the electron beam from dispersing.

High voltages are supplied into an electron gun, which then expels a high-velocity stream of electrons with the help of cathodes, anodes, focusing coils, and magnetic fields. The intensity of electron beams is 100-1000 times higher than arc welding, allowing deep penetration and narrow heat-affected zones.

EBW different weld profiles
EB weld root inspection – different weld profiles

Similarly to plasma welding, the EBW process can be run in low power, medium power and high power aka keyhole mode. The low power mode is used to produce extremely fine welds, which can be as small as 20µm. Medium power is generally used for weld thicknesses from 1mm to 20mm, anything over that is in the domain of high power electron beam welding. Running the machine in keyhole mode can penetrate up to 300mm of steel and is known to create stable, good-quality welds for material thicknesses over 200mm.

Recent breakthroughs in EBW allow local welding with a workpiece larger than the vacuum chamber adding a bit more versatility to the welding process. This welding technology is achieved by having only the electron beam gun inside a vacuum box while the workpiece itself remains outside of the vacuum chamber.

Materials

The technology behind electron beam welding allows various metals to be welded together, including dissimilar metals, since it is mostly performed in a vacuum environment. EBW is mainly used with these materials:

Equipment

The main components of electron beam welding equipment are the following:

Electron Gun

The main components of an electric gun are the cathode, anode, grid cup and focusing unit. There are two types of electron guns. Self-accelerated electrons are accelerated using the potential difference between the cathode and the anode. Work-accelerated electrons are accelerated using the potential difference between the cathode and the workpiece.

Power Supply

DC power is used in the electron beam welding method with 5-30 volts for small equipment and 70-150 volts for large equipment.

Vacuum Chamber

The pressure for partial vacuum is at 10-2 to 10-3 mbar, while hard vacuum uses a range of 10-4 to 10-5 mbar.

Applications

The diversity of EB welding allows the ability to weld metals with varying thicknesses, making it a flexible option for welding complex parts such as transmission assemblies or small electronic components. It’s also a great option for welding metals with different melting points and thermal conductivities.

As electron beam welding technology is highly automated and delivers a clean result with repeatable accuracy and minimal distortion, there is no need for post-weld machining. Some of the industries benefitting from this include aerospace, automotive, medical, nuclear, oil and gas.

Electron Beam Welding vs Laser Welding

While the basic principle of electron beam welding and laser welding is similar on the surface, there are some distinct differences that make each of them unique:

Heat source

EBW uses a focused beam of electrons, while the laser welding process uses photons to generate heat.

Vacuum environment

Both processes can be performed in a vacuum environment, protecting the weld pool from contamination against air molecules and improving the weld quality. Conventional laser welding is done under atmospheric conditions with the help of inert gas shielding or a combination of gases.

Welding speed

Laser beams require high welding speeds since it vaporises the base materials, creating fumes. The electron beam welding process can accommodate different welding speeds while still achieving deep welds.

Power consumption

Electron beam welding converts around 85% of the electrical input into usable power. In comparison, laser welding only converts up to 40% of electricity to usable power, even with the use of modern tools.

Advantages of Electron Beam Welding

  1. Can reproduce precise welds at rapid weld speeds.

  2. A narrow heat-affected zone allows for welding delicate assemblies.

  3. Clean welds since EBW is done in a vacuum environment.

  4. Ability to join dissimilar metals.

  5. High weld penetration range.

  6. Most penetration depths don’t require filler material.

Disadvantages of Electron Beam Welding

  1. High initial costs.

  2. EBW machinery requires frequent maintenance to function correctly.

  3. The process requires highly skilled machine operators.

  4. The size of the vacuum chamber limits weld size for traditional EBW.

  5. Extreme precaution is required from radiation.

Satisfy the team – Rafal

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Becoming a member of Alpha Producing in excess of 9 a long time in the past, Rafal Laczkowski has develop into essential in making certain our products get to our buyers in pristine situation as promptly as possible.

Rafal joined the business in the dispatch division. After just one yr of doing the job within just the staff, Rafal’s challenging operate and motivation have been recognised – earning him a promotion to supervisor level.

Despite his enjoy for his staff and travel to assure his position was accomplished to a substantial standard, Rafal experienced often dreamed of a unique profession route.

Following 8 many years inside Alpha Producing, viewing the opportunities as a result of coaching and expansion offered, Rafal made a decision it was time to chat to Paul Clews, Taking care of Director of Alpha Production, about his childhood aspiration.

Rafal stated, “To be a driver, it was my aspiration. A right dream. Soon after 8 several years doing the job for Alpha Manufacturing, I approached Paul Clews and questioned him if there had been any opportunities to develop into a HGV driver.”

Alpha Manufacturing is dedicated to supporting apprentices and staff to achieve their most effective. This situation was no different. The Alpha management group agreed to cover all prices of Raf’s teaching and ensure him a position as a shipping driver upon completion.

Paul Clews, Handling Director of Alpha Production, reported, “I’m so proud that we have been able to assist Raf get to where by he needed to be. It is significant to us as a small business to know our staff are joyful and fulfilled.”

“A important target of The HEX Group is to ensure our crew has the teaching prospects to attain their objectives.”

Reflecting on the transition to his new aspiration function, Rafal claimed, “I’ve been driving for just more than a yr now. This work is best – from commence to finish.”

“My standard working day starts with vehicle inspections, guaranteeing the car or truck is harmless on the street. Then, it’s time to supervise the merchandise hundreds making sure that every thing is secured effectively to avoid hurt.”

“I can be executing a few of deliveries a day or undertaking just one for a longer time supply to spots these as Southampton. When I’m driving, you can uncover me listening to the likes of Michael Jackson, the Pet Store Boys, and other pop classics to move the time.”

Rafal’s determination to making certain that Alpha Manufacturing’s products get to our consumers is second to none. We appear ahead to sharing much more about his function below soon.

Plasma Arc Welding (PAW) Explained

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Plasma welding is an arc welding process that uses a plasma torch to join metals. The principle of this method is derived from GTAW aka TIG welding, where an electric arc is struck between the electrode and the workpiece.

Let’s dig deeper and explore what plasma welding is all about.

What Is Plasma Welding?

Plasma arc welding (PAW) is a fusion welding process that uses a non-consumable electrode and an electric plasma arc to weld metals. Similarly to TIG, the electrode is generally made out of thoriated tungsten. Its unique torch design produces a more focused beam than TIG welding, making it a great choice for welding both thin metals and creating deep narrow welds.

Plasma welding is often used to weld stainless steel, aluminum, and other difficult metals compared to traditional methods. Similarly to oxy-fuel welding, this process can also cut metal (plasma cutting), making it a versatile tool for fabricators and manufacturers.

Plasma Arc Welding Process




Plasma Arc Welding

The plasma arc welding process revolves around the principle of striking an arc between a non-consumable tungsten electrode and the workpiece. The plasma nozzle has a unique design feature, where the electrode is located within the body of the torch. This allows the arc plasma to exit the torch separated from the shielding gas envelope.

Additionally, the narrow opening of the nozzle increases the plasma gas flow rate, allowing for deeper penetration. While filler metal is typically supplied at the weld pool’s leading edge, it is not the case when creating root pass welds.

The complexity of the plasma welding torch sets it apart from gas tungsten arc welding. Plasma welding torches operate at very high temperatures, which can melt away their nozzle, making it a requirement to always be water-cooled. While these torches can be manually operated, nowadays, most modern plasma welding guns are designed for automatic welding.

The most common defects associated with plasma welding are tungsten inclusions and undercutting. Tungsten inclusions occur when the welding current exceeds the capabilities of the tungsten electrode and small droplets of tungsten get entrapped in the weld metal. Undercuts are generally associated with keyhole mode PAW welding and can be avoided by using activated fluxes.

Plasma Arc Welding Operating Modes

Three operating modes are used in plasma welding, wherein it can be operated at varying currents:

Microplasma (0.1 – 15A)

This operating mode can run arcs at low currents and remain stable up to 20mm arc length.

Microplasma welding is used to join thin sheets up to 0.1 mm in thickness, which is optimal for creating wire meshes with minimal distortion.

Medium current (15 – 200A)

The characteristics of the plasma arc are quite similar to TIG welding, but the arc is stiffer since the narrow opening of the torch restricts the plasma. We can increase weld pool penetration by speeding up the plasma flow rate, but this increases the risk of shielding gas contamination.

Medium current or melt-in mode offers better penetration than TIG and improved protection. The only drawback is that the torch requires maintenance and is bulkier compared to a TIG torch.

Keyhole mode (over 100A)

A powerful plasma beam is used to engage in high-current aka keyhole mode by increasing the gas flow and welding current. This mode allows deep penetration, using a single pass (up to 10mm thick for some materials) to create a consistent weld pool from molten metal.

Similarly to electron beam welding, the keyhole mode is great for welding thicker materials at high welding speeds. To guarantee satisfactory welds, filler material is generally added. Its welding applications include mechanised welding, positional welding, and pipe welding.

Comparison of Plasma and TIG Welding

Normally, a tungsten electrode is used in TIG welding to strike an arc between the torch and the workpiece. The plasma process works similarly but uses a different setup in its welding torch. The constricted nozzle design allows electrons to move at high velocities. This ionises the gas, creating a plasma jet with a high heat concentration, offering deeper penetration.

As plasma welding offers greater precision than TIG welding, it has a smaller heat-affected zone which is perfect for creating narrower welds. Ideally, plasma welding is a better choice than TIG welding, as it is an evolution of the latter. The technology behind its equipment allows it to run with lower current demand, better arc stability which leads to better stand-off distance, and better tolerances if the arc length is changed.

TIG welding however is a simpler method due to the complex parameters available for plasma gas welding. An operator would need extra training in order to transition from the already advanced TIG welding to PAW. And last, TIG welding equipment is cheaper and requires less maintenance than plasma arc welding’s sensitive and complex torch.

Materials

Similarly to TIG welding, plasma welding is suitable for the majority of well-known metals, although it might not be the most cost-effective solution for some of them:

  • Alloy Steel

  • Aluminium

  • Bronze

  • Carbon Steel

  • Copper

  • Iron

  • Inconel

  • Lead

  • Magnesium

  • Monel

  • Nickel

  • Stainless Steel

  • Titanium

  • Tool Steel

  • Tungsten

Equipment

The key components of plasma welding equipment are:

Plasma torch

Plasma arc welding (PAW) torch operating principle
Plasma torch – plasma gas is separated from the shielding gas envelope.

 

The unique design of the water-cooled plasma torch is the main distinguishing factor from other welding processes. Its operating principles have already been explained in previous sections.

Depending on the weld material and desired weld characteristics, different types of nozzle tips can be selected.

Control console

While conventional welding techniques directly connect a torch to a power source, plasma arc welding uses a control console between the two.

Some of the console features are the torch protection circuit, high-frequency arc starting unit, power supply for the pilot arc, water, and gas valves, individual meters for plasma, and shielding gas flows.

Power supply

Plasma arc welding uses DC power (rectifiers or generators) of at least 70 volts for open circuit voltage with drooping characteristics to have greater control in generating weld beads.

Gases used

  • Plasma gas – exits the constricting nozzle separately from the shielding gas envelope and becomes ionised

  • Shielding gases (argon, helium, hydrogen) – inert gas protects the weld from the atmosphere

  • Back-purge and trailing gas – certain materials require special conditions

Wire feeder

Plasma welding may use wire feeders with a constant velocity that can be modified to run from 254 mm per minute to 3180 mm per minute.

Applications

Steel tubes

PAW is a great welding method in manufacturing steel tubes as it can be performed at high-speed welding with great metal penetration. Some industries prefer the plasma welding process to conventional TIG since its system is faster and uses less filler material.

Electronics

One of the welding parameters of the plasma welding process is it can run at low current modes. This mode allows small metal component welding, which deals with delicate materials sensitive to environmental factors.

Medical industry

Medical devices require precise components in order to run effectively. PAW is perfect for welding these components as it can reliably create a consistent weld bead.

Advantages of Plasma Welding

  1. Can be operated in every welding position.

  2. Fast travel speeds from concentrated heat input.

  3. Keyhole welding allows for complete penetration.

  4. Low current mode is suitable for thin and sensitive components.

Disadvantages of Plasma Welding

  1. Expensive equipment and components.

  2. Requires training and skill to create good welds.

  3. Produces 100dB noise.

  4. Creates ultraviolet and infrared radiation.

  5. Water cooling is necessary because of high working temperatures.

  6. Delicate equipment needs a higher amount of maintenance.

Pricing for Inventor Documents Now Obtainable

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In addition to the aid for SolidWorks documents we additional before this calendar year, we’re now ready to quote file sorts native to Autodesk Inventor as properly.

The listing of file sorts our platform can now quotation is as follows:

  • .ipt – Inventor section file
  • .sldprt – SolidWorks aspect file
  • .stp – the universal 3D CAD file 
  • .dxf –  2D drawing file (can quotation flat laser reducing work opportunities)
no price difference
.stp or .ipt, no change in pricing

So as you can see from the screenshot above, there is no require to commit time changing the files to .stp when using Inventor from now on. 

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