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1. ELECTRON BEAM WELDING Submitted by: Ankit Saxena PGMSE-136013 Submitted to: Mr Harish Arya

2. Introduction Electron Beam Welding is a fusion welding which a beam of high-velocity electrons is applied to the material to be joined. The work-piece melt as the kinetic energy of the electrons is transformed into heat upon impact. iii. The EBW process is well- positioned industries with highest quality welds and machine designs that have adaptable to specific welding tasks and environments. i. process in ii. to provide proven to be Fig.1: Key hole penetration in EBW production

4. Electron Beam? In welder “boiled off” as current passes through filament which is in a vacuum enclosure. an electron electrons beam are i. An generated by a negatively charged filament and bias cup and a charged anode, accelerates the electrons 50% to 80% of the speed of light and shapes them into a Beam. electrostatic field, ii. positively to about Fig 2:Electron beam source for EB disposal

5. How does the Process Work? The electron beam gun has a tungsten filament which is electrons. i. heated, freeing The electrons are accelerated from the source with high voltage potential betweena cathode and anode. ii. iii. The stream of electrons then pass through a hole in the anode. The beam is directed by magnetic forces of focusing and deflecting coils. This beam is directed out of the gun column and strikes the work piece. The potential energy of the electrons is transferred to heat upon impact of the work piece and cuts a perfect hole at the weld joint. Molten metal fills in behind the beam, creating a deep finished weld. iv.

6. Steps Used in EBW process Joint preparation. Cleaning of work piece. Fixturing of work piece. De-magnetization of work piece. Setting up work piece in chamber. Pump down air form chamber. Carry welding process.

7. Classification of EBW Machines • High voltage machine (U =150 kV) • Low voltage machine (U=60kV) • High vacuum machine • Fine vacuum machine • Atmospheric machine (NV-EB welding) • Conveyor machine • Clock system • All-purpose EBW machine • Local vacuum machine • Mobile vacuum machine • Micro and fine welding machine By Accelerating Voltage By Machine concept By pressure

8. High vacuum machine Fine vacuum machine Atmospheric machine (NV- EB welding)

9. Machine Concept - Conventional Plant EBW Clock System Machine

10. EBW Conveyor Machine

11. Comparison with different welding techniques on the basis of Parameter PARAMETER TIG PLASMA LASER EB Power input to W-P 2kW 4kW 4kW 5kW Total power used 3kW 6kW 50kW 6kW Traverse speed 2mm/s 5.7mm/s 16mm/s 40mm/s Positional welding Good penetration Good penetration Yes Require optics to move the beam Requires mechanism to move the beam Distortion shrinkage Nominal significant in V- shaped weld Nominal significant in V- shaped weld Small Minimum Minimum Minimum

12. PARAMETER TIG PLASMA LASER EB Special process requirement Normal light screening Normal light screening Safety interlock against misplaced beam reflection Vacuum chamber-ray screen Surface geometry Underside protrusion Underside protrusion Very fine ripples Ruffled swarf on back face

13. Comparison of conventional weld and EB weld

14. EBW is suitable for a variety of difficult applications, such as welding structures on which the reverse side of the butt is inaccessible ; gravity welding of thin metal ; and welding in various spatial positions. i. This Provides a low level of over all heating of the structures ; and has the ability to vacuumed the inner volume simultaneously, which is suitable for sealing instruments. Because EBW is an automated process , the welded joint quality is consistent . ii. iii. The process does not require shielding gases , tungsten electrodes , or edge preparation for welding thick metal . iv. Finally , it can be used to weld some joints that cannot be made by other welding processes.

15. Compared processes, EBW improves joint strength 15 per cent to 25 per cent. with arc welding v. It zone(HAZ), lighter-weight products. has a narrow which heat-affected results vi. in vii. Geometric shapes and dimensions are highly stable, when it is used operation. particularly as a finish viii. It eliminates oxide and tungsten inclusion sand removes impurities. The crystalline structure. weld metal has a fine ix.

16. Graph showing areas of different welding processes on the plot of feature size v/s power density.

17. Advantage of EBW In Vacuum a) Thin and thick plate welding (0,1 mm bis 300 mm). b) Extremely narrow seams (t:b = 50:1). c) Low overall heat input => low distortion =>Welding of completely processed components. d) High welding speed possible. e) No shielding gas required. f) High process and plant efficiency. g) Material dependence, often the only welding method. At atmosphere a) Very high welding velocity. b) Good gap bridging. No problems with reflection during energy entry into work piece.

18. Disadvantage of EBW In Vacuum • Electrical conductivity of materials is required. • High cooling rates => hardening => cracks. • High precision of seam preparation. • Beam may be deflected by magnetism. • X-ray formation. • Size of work piece limited by chamber size. • High investment. At Atmosphere • X-ray formation. • Limited sheet thickness (max. 10 mm). • High investment. • Small working distance.

19. Field of Application Industrial areas • Automotive industries • Aircraft and space industries • Mechanical engineering • Tool construction • Nuclear power industries • Power plants • Fine mechanics and electrical • Industries • Job shop

20. Material • Almost all steels. • Aluminium and its alloys. • Magnesium alloys. • Copper and its alloys. • Titanium. • Tungsten. • Gold. • Material combinations (e.g. Cu-steel, bronze-steel). • Ceramics (electrically conductive).