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In-Vacuum-Chamber Electron Beam (EB) Welding and Processing

Electron beam (EB) welding is a fusion welding process whereby electrons are generated by an electron gun and accelerated to high speeds using electrical fields. This high speed stream of electrons is tightly focused using magnetic fields and applied to the materials to be joined. The beam of electrons creates kinetic heat as it impacts with the workpieces, causing them to melt and bond together.

Electron beam welding is performed in a vacuum environment as the presence of gas can cause the beam to scatter. Due to it being a vacuum process and because of the high voltages used, this welding method is heavily automated and computer controlled. As a result, specialised fixtures and CNC tables are used to move the workpieces inside the welding vacuum chamber.

TWI provides in-vacuum-chamber electron beam (EB) welding and processing, as well as a range of related processes, products and services.

TWI is active in the development of new capability as well as deployment of established in-chamber EB welding at a range of power levels, including:

High power – welding of thick-section material using a high accelerating potential (up to 175kV) and high beam power (up to 100kW) to penetrate steel up to 300mm thick, while achieving a stable weld keyhole in sections of 200mm or more. Application fields are often in the power sector, nuclear waste encapsulation and for value-adding in primary manufacture.

Medium power (as shown in the video) – the main users of EB welding are the aerospace and automotive sectors. Here weld penetrations are typically between 1 and 20mm. Welds in turbine engine drums, control actuators, heat exchangers, gear clusters and turbochargers are common; many oil and gas industry instrumentation assemblies are also welded/hermetically sealed. The process is beneficial as the resulting welds, having been made with a very localised heat source, which is consistent through the thickness being welded, typically have low distortion and allowing parts to be welded at or very close to final size/geometry.

Low power – EB welding machines may be configured to produce very fine, intense beams with spot sizes at the workpiece as small as 20µm. These beams may be used effectively to create very small welds, cuts, holes and other features.

Welding, as at higher powers, is a keyhole process.

 

Capabilities

  • Weld thickness range (<0.1 to >200mm)
  • Single pass welding
  • Autogenous process (normally no filler)
  • Low heat input & distortion
  • Narrow, high aspect ratio, heat affected zone (HAZ)
  • High speed and productivity
  • Up to 100kW beam power
  • Non-contaminating atmosphere
  • Most metals and dissimilar combinations
  • Large welding chamber machines
  • Monitoring, quality assurance (QA) and calibration know-how 

 

Applications and Services

  • Welding and brazing
  • Feasibility and procedure qualification
  • Low volume, very high value adding, specialist production welding
  • Applications in most industry sectors
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