Technological feasibility of EMW for all suggested material combinations

Feasibility of electromagnetic welding is regarded as proved if welding can be reproducibly achieved for at least one set of parameters. In order to determine reasonable parameter ranges, numerical simulations and experimental spot tests have been carried out at the
three research institutes dealing with investigation of the EMW process itself (i.e. FRAUNHOFER, BWI and INNOVALTECH). Documentation of the feasibility in this deliverable is validated via photos of successfully welded specimens and a list with suitable parameters and conditions for achieving a satisfactory result.

Sheet metal welding

Feasibility of all material combinations selected for investigation of EMW of sheet metal parts has been proved by FRAUNHOFER. For all tests the pulsed power generator PS 103-25 Blue Wave by PST products was used. The capacitance of the pulsed power generator was selected as 300 μF. A tridentally shaped tool coil with an active length of 100 mm was connected to the pulsed power machine. The specimen width was chosen as 100 mm corresponding well with the active length of the tool coil. The target thickness was 2.0 mm in all cases. A sketch of the geometrical setup used for the feasibility proof is shown in Figure 1. Here, for all relevant geometrical parameters, which are valid for all cases presented in the following, the values are directly given. All parameters, which vary in the cases presented below are given as variables. 

Feasibility of joining of aluminium (EN AW-1050) flyers and copper (Cu-DHP) target sheet metal parts has also been proved by BWI. For all tests the pulsed power generator Pulsar MPW 50/25 was used. The capacitance of the power generator was selected as 160 μF. The flat tool coil applied is illustrated in Figure 2. This rectangular coil was manufactured by Poynting GmbH (Dortmund). Similar to the coils with tridentally-shaped conductor geometry developed at FRAUNHOFER, it has an active section of the winding, which is used for welding, while other parts of the winding serve for closing the current loop only. The width and length of the active section of the conductor are 10 mm and 150 mm, respectively.

Tube welding

Feasibility of all material combinations selected for investigation of EMW of tube metal parts has been demonstrated by BWI and INNOVALTECH.
At BWI, the pulsed power generator Pulsar MPW 50/25 by Pulsar was used. The capacitance of the power generator was selected as 160 μF. Three different coil systems were employed to realise the joint, in order to vary the discharge current and discharge frequency:

1. Multi-turn coil with a field shaper
2. Single-turn coil with a field shaper
3. Single-turn coil with a field shaper and with a transformer

The flyer tubes had an outer diameter of 28 mm and 2 different wall thicknesses: 0.9 and 1.3 mm. For the target material, rods (i.e. solid internal workpieces) and tubes were selected. The experimental set-up of a tube-to-rod configuration with shoulder and a tubeto-
tube configuration is shown in Figure 3.

At INNOVALTECH, the pulsed power generator Pulsar 25-9 by Pulsar was used. The capacitance of the pulsed power generator was selected as 690 μF. A one turn tool coil with an active length of 15 mm was connected to the pulsed power machine. The specimen external tube diameter was chosen as 28 mm. The target piece is a full solid part in all cases. A sketch of the geometrical setup used for the feasibility proof is shown in Figure 4. Here, for all relevant geometrical parameters, which are valid for all cases presented in the following, the values are directly given. 

You can read the full deliverable here.