Glossar

A

Acceleration voltage

High voltage potential between cathode and anode which accelerates the electrons into a beam.

Air-lock machine

EB welding machine with a separate chamber partition for loading/unloading in order to eliminate the evacuation time by operating parallel to processing time.

Anode

Grounded electrode within the beam generation system, forming an electrical potential with the cathode.

Atmosphere

Free atmosphere at 1 atm pressure surrounding the beam generator and the workpiece to be welded in Non-vac or In-air processing.

Automation

EBW machines run fully automatic. For mass production they can be automatically linked to other equipment for pre and post EB process operations.

B

Bead on plate weld

Simulated welding run into material with no joint.

Beam adjustment

Magnetic alignment of the beam axis relative to the focus coil axis centre-line.

Beam current

Electrical current(measured in amps) flowing in the electron beam.

Beam energy

Kinetic energy of the electrons impinging the workpiece; a product of the elementary charge and the accelerating voltage. Sometimes confused with the term - beam power.

Beam generator

Source of an electron beam.

Beam power

Product of beam current (mA) and high voltage (kV), measured in kilowatts (kW).

Beam profile

Envelope of the electron beam as it traverses its way from the beam generator to the workpiece.

C

Cathode

Electron emitter; part of the beam generator. It is heated to very high temperatures to free electrons from its surface and is connected to the negative high-voltage potential.

Chamber machine

Basic type of an EB welding machine having a suitably designed working chamber which can accessed by an opening and closing door.

Cleaning

Any kind of contamination of the parts to be welded will adversely affect the weld quality; therefore cleaning prior to welding is an essential step.

Consumption

EB welders need (only) electric energy from supply for operation; compressed air in low amount is used for valve operation.

Control

EB machines and processes are CNC or PLC controlled.

Cosmetics

Shallow welding run (with adapted parameters) to reduce or smooth-the crown or root part of the penetration weld.

Cycle time

Total time to perform a complete EB machine’s work-cycle, independent of the number of parts processed in doing so.

D

Deep welding effect

The extreme high power density of the beam not only melts the workpiece metal but also evaporates it locally and forms a key hole. By this means the beam penetrates into the material up to a depth controlled by the parameters used. In moving the beam along the path a deep weld is performed from the solidifying the molten material behind the key-hole.

Deflection

The beam of electrons can be deflected by magnetic (and/or more seldom electric) fields which are regulated by the machine’s control.

Deflection grid

Digital array of deflection positions which the beam can target on the workpiece.

Deflection pattern

Digital or analogue figure which can be transposed by beam onto the workpiece.

Deflection system

System of magnetic coils and controlled constant current sources which produce static or dynamic beam deflection movement.

Deformation

Thermal distortion of the workpiece; a result of high energy input.

E

EB

Abbr.: electron beam

EB brazing

electron beam brazing

EB drilling

electron beam drilling

EB generator

electron beam generator

EB machine

electron beam machine

EB treatment

electron beam treatment

EB welding

electron beam welding

Electron

Elementary particle having a mass of 9.1 x 10^-28 g and carrying an negative electrical charge of 1.6 x 10^-19 As.

Electron beam

Particle beam produced by a generator to process metallic materials.

Electron beam brazing

Fusion brazing by using the heat from an impinging electron beam.

Electron beam drilling

Perforation of metallic material by means of single eb-pulse percussion processing [material ejected from eb-pulse generated key-holes].

Electron beam generator

Self-contained unit, forming part to an EB welding machine, which develops the electron beam.

Electron beam generator

Self-contained unit, forming part to an EB welding machine, which develops the electron beam.

Electron beam hardening

A special process to locally transform the surface by means of an electron beam – with the objective of increasing the hardness (especially without melting the surface). Self quenching is performed without any additional cooling process.

Electron beam machine

Machine for processing any work by means of an electron beam.

Electron beam treatment

Processing any work by means of an electron beam.

Electron beam welding

Fusion welding by using the heat from an impinging electron beam.

Energy input

Amount of beam energy transformed into heat within the workpiece.

Evacuation time

Time to achieve operating pressure.

F

Fast beam deflection

High-speed magnetic deflection of an electron beam. Point-to-point frequencies up to 1 MHz.

Feasibility of welding

Property of a given metal or metal combination to achieve successful fusion welding without unacceptable inclusions.

Filler material

Additional metal (generally in wire form) to fill gaps or to alloy the weld zone material.

Floor-to-floor time

Time to process one (1) workpiece from a machine or production line – used in mass production.

Focus

Plane of an electron beam where its diameter is at a minimum.

Focus coil

Current-current torriodial coil; producing a magnetic focus effect on the electron beam.

Focussing

See: focus coil

G

Gun column

Colloquial term for electron beam generator.

H

Hardening

Transformation of steel or cast iron microstructure to martensite.

I

Indexing machine

High volume production EB machines equipped with an indexing table carrying a minimum of two stations for loading/unloading and processing, respectively.

Interlinking

This means the automated integration of an EB welding machine to other equipment within a production line.

J

Job shop

Plant for sub-contract electron beam production, for both one off and mass production.

Joint preparation

Particularly the form of the joint edges. Most common type used in EB welding is a butt joint with theoretical zero-gap.

K

Key hole

Metal-vapour gas capillary opening developed in deep welding processing.

M

Magnetic lens

See: focus coil

Mass production

High volume production achieved by EB processing with minimum down times.

Material assembly

EB welding is able to join dissimilar materials.

Metallurgy

The resultant microstructure resulting from the fusion process created by the electron.

Microstructure

Composition and configuration of the basic elements within a metallic alloy or compound.

N

NonVac

Abbr.: Nonvacuum electron beam welding

Nonvacuum electron beam welding

Application of an electron beam (generated in a high-vacuum unit) out of vacuum, i.e. in free atmosphere.

O

Observation

The process area can be observed by means of light-optical systems (via TV camera) or by using reflected electrons from a scanned beam.

Operation costs

Low operation costs are a general characteristic of EB machines.

P

Production cell

EB machine interlinked to other operating units within a production cell.

Production line

EB machine interlinked to other operating units within a production line.

Protection gas

In contrast to all other fusion welding processes EB welding does not need any gas to protect weld metallurgy.

Pumping unit

Equipment to develop a vacuum within the EB machine, in order to develop and weld with the electron beam.

Q

Quality

In particular the properties of any EB processing. Quality levels are defined in certain norms.

R

Radiological protection

EB produces unwanted X-rays as a by-product. Human have to be protected from high levels of X-radiation, this is achieved within the EB-machine’s design concept.

Rotary indexing machine

See: indexing machine

S

Single-item production

Complex and expensive parts are processed as single processes in direct contrast to mass production.

Smoothing

See: cosmetics

Surface modification

By local heat treatment – without or with melting the surface – the EB can change the metallurgical structure within a certain depth of the surface. This includes hardening, remelting, alloying, embedding, structuring etc.

T

Technology

A set of parameters used within a special process or application.

V

Vacuum

In order to avoid scattering of the electrons by gas molecules the beam generator (~10^-4 mbar) as well as the working chamber (10^-2 to 10^-6 mbar) are evacuated.

Vacuum chamber

See: working chamber

W

Waist of beam

In contrast to a laser beam, the electron beam is not focussed to a precise level (a point) but exhibits a focus-waist (a few millimetres in length). EB processes are therefore less sensitive to small tolerances in working distance.

Wall-plug efficiency

The effectiveness of converting electrical energy into thermal welding power.

Wehnelt electrode

This solid grid cup (placed between cathode and anode within the beam generating system) controls the beam current by means of its negative field-potential.

Weld depth

The penetration depth of the key-hole determines the depth of the achievable weld.

Weld profile

The shape and form of the solidified metal seen in a transverse weld cross-section. The two fusion faces (flanks) of EB welds are typically parallel; therefore reducing the angular shrinkage and workpiece distortion.

Weld with

Measure of the distance between the two fusion faces of a weld profile.

Welding

In particular, processes and their result within the solidified melting pool with respect to the composition and properties of the weld metal.

Welding technology

In particular, whole set of parameters used in a special welding task.

Working chamber

Evacuated chamber of an EB machine where the EB process takes place.

X

X-rays

Short-wave electromagnetic radiation which occurs parasitically with any electron beam process. Its “hardness” (ability for penetration) increases with the level of the accelerating high voltage.