How does laser power modulation affect weld depth?

By the lateral movement of the laser beam the seam width is increased as well as the connection width. Furthermore the superposed oscillation leads to a decrease in the weld depth. In general a different deposition of the laser power can be seen by use of spatial power modulation compared to welding without oscillation (Fig. 5 ).

How many m a weld depth is required?

The necessary connection width of more than 250 µm could be reached as well as a weld depth between 200 and 500 µm with demonstrated air tightness and therefore liquid-tightness. The power loss calculated for the measured resistance was 14.4 W which is acceptable compared to the total capacity of the pack.

How is a PCM Weld done?

The welding is done while the cell is charged and filled with the cathode and anode material, the separator and the liquid electrolyte. The copper collector is also used to encapsulate the PCM, therefore the weld must be liquid-tight.

What is a light weight energy storage device?

For the use in electrically powered vehicles a light weight energy storage device has been designed by Fraunhofer in which 4800 Li-Ion cells of form-factor 18650 are connected. The capacity of the full pack is 36 kWh with a Voltage of about 300 V. To reach these values the battery cells have to be connected in parallel and serial configuration.

Which parameter set has lowest welding depth?

As the parameter set with an energy per section of ES = 3 J/mm and A = 0.6 mm shows the lowest capability regarding the welding depth only the parameter set of A = 0.4 mm and A = 0.5 mm with ES = 3 J/mm were analyzed further.

Are welds liquid-tight?

As the welds show air tightness and the viscosity of the PCM is much higher than the viscosity of air, the welds can also be considered liquid-tight. Nevertheless few welded samples showed leaking spots. The leakage in these cases can be traced back to inaccuracy in positioning of the seam.