How to fill the exit hole of the FSW welded material?

An exit hole is left by the FSW tool during the removal phase. This hole at the end of the bead has no impact on the quality of the weld. It can be prohibitive for certain applications of circular welds in specialized fields such as the aeronautical industry.
To avoid this exit hole, we have designed an FSW welding head with a retractable pin. In this context, the welding phase is carried out over a complete turn in order to close the weld. The retractable pin is pulled up when the weld area is overwritten.