Electron Beam Machining

Question 1

Electron Beam Machining

Answer 1

Electron beam gun emits a continuous stream of electrons (1billion/sec) which are generated by heating a tungsten (W) or tantalum (Ta) filament placed in a vacuum chamber to >2,000°C

Beam spot gets focused to Ø0.25-1mm (Ø0.025mm possible) and accelerated to ~75% of the speed of light through electromagnetic lenses

Kinematic energy of the electrons gets converted into thermal energy >200 kW/mm2 that melts and vapourises material along a programmed electron beam path

Question 2

Electron Beam Machining Advantage

Answer 2

High precision cutting of any known material

Drilling of small holes (<0.05mm) with high depth-diameter ratio 100:1; slots 0.025mm

No cutting forces, no tool wear

Ideal for micromachining

Question 3

Limitations of Electron Beam Machining ?

Answer 3

High energy consumption

Expensive equipment

Thin parts only .25-6.5mm

Question 4

Application of EBW?

Answer 4

Welding

Electron Beam Melting

Question 5

Variation of EBM?

Answer 5

Electron Beam Melting

Electron Beam Welding

Question 6

EBM – Advantages?

Answer 6

High precision cutting of any known material

Drilling of small holes (<0.05mm) with high depth-diameter ratio 100:1; slots 0.025mm

No cutting forces, no tool wear

Ideal for micromachining

Question 7

EBM - Limitations

Answer 7

Thin parts only 0.25-6.5mm; tolerances 10% of hole diameter

High energy consumption

Expensive equipment

Question 8

EBW – Advantages

Answer 8

Any metal can be welded; Welding of steel 1mm-150mm, Aluminium <450mm thickness

Good for welding dissimilar metals

Good surface finish Ra 1.5m

Speeds are similar to conventional welding; small welds 12m/min

Suitable for deep and narrow joints (fusion zone 25:1)

Small Heat Affected Zone (HAZ) with little thermal distortion

Question 9

EBW – Limitations

Answer 9

High cost (U$0.5-1M)

Complex equipment requiring highly skilled labour

Best weld quality only achieved in vacuum chamber (often with a considerable “pump-down time”)

Workpiece dimensions are limited to chamber size

Requires electromagnetic shielding from harmful X-rays; indirect viewing systems to protect from visible radiation

Extensive joint preparation and alignment required