ELECTROMAGNETICFORMING Members :- 111638 - Himanshu Gupta 111639 - Himanshu yadav 111640 - kamlesh kumar 111641 - kapil kumar

FORMINGForming, ormetal forming, is themetalworkingprocess of fashioning metal parts and objects through mechanical deformation

Workpiece is reshaped without adding or removing material, and its mass remains unchanged

Forming operates on thematerials scienceprinciple ofplastic deformation, where the physical shape of a material is permanently deformed.

ELECTROMAGNETIC FORMINGElectromagnetic Forming (magnetic pulse forming) is a process that forms a work piece by using intense pulsating magnetic forces.

The process can also be used for internal forming by placing a coil inside the tube causing the tube to expand.

The process is used extensively as an assembly technique to join tubular parts to other components.

The process is used to assemble steering gear, coaxial cable and various parts that would be difficult to assemble by other methods.

EXAMPLEA pinched aluminium can, produced from a pulsed magnetic field created by rapidly discharging 2 kilojoules from a high voltage capacitor bank into a 3-turn coil of heavy gauge wire.

HISTORYElectromagnetic Metal Forming machine built by General Atomic in the early 1960s and used by GM as a manually operated single station assembly machine.

After that, EMF technique was used in Iraq in the 1960s, due to its advantages in enabling the fabrication of many complex geometry parts and enhancing the formability of low ductility materials

PRINCIPLE OF OPERATION

In this process, electrical energy is converted to mechanical energy with the use of a magnetic field.

When an electrical current is rapidly introduced through a conductor (wire), a magnetic field is created around the wire.

The sudden introduction of a magnetic field creates eddy currents that flow in opposite direction in any conductor nearby.

The eddy currents develop their own magnetic field and cause a repelling force.

The high work coil current (typically tens or hundreds of thousands ofamperes) creates ultrastrong magnetic forces that easily overcome theyield strengthof the metal work piece, causing permanent deformation.

The metal forming process occurs extremely quickly (typically tens ofmicroseconds) and, because of the large forces, portions of the workpiece undergo highaccelerationreaching velocities of up to 300 m/s.

SETUP OF EMF :-

COMPARISON WITH CONVENTIONAL FORMING

ADVANTAGESClose tolerances are possible asspringbackcan be significantly reduced.

Improved formability (the amount of stretch available without tearing)

Mechanical contact with the workpiece is not required, this avoids surface contamination and tooling marks. As a result, a surface finish can be applied to the workpiece before forming.

The tool and the assemblies of the electromagnetic equipment dont need lubrication.

DISADVANTAGESNot any shape is suitable for forming electromagnetically. The forming forces are created as a result of the interaction of the current induced in the work piece with the magnetic field of the inductor.

Non conductive materials cannot be formed directly, but can be formed using a conductive drive plate

The high voltages and currents involved require careful safety considerations

APPLICATIONS :-The forming process is most often used to shrink or expand cylindrical tubing, but it can also form sheet metal by repelling the work piece onto a shapeddieat a highvelocity.

High-quality joints can be formed, either by electromagnetic pulse crimping with a mechanical interlock or byelectromagnetic pulse weldingwith a true metallurgical weld. Since the forming operation involves highaccelerationand deceleration, mass of the work piece plays a critical role during the forming process.

The process works best with goodelectrical conductorssuch as copper oraluminum, but it can be adapted to work with poorer conductors such assteel.

Engine nacelles made in a single piece, electromagnetic riveting guns and hammers (developed by NASA in the mid 1980s) used in the assembly of aircraft skins, and dent pullers

REFERENCES

"Electromagnetic Metal Forming Handbook".An English translation of the Russian book by Belyy, Fertik, and Khimenko.

Analysis of theelectromagnetic forming process .by J Jablonski