Instead of a clamping glass as the upper pressure tool, a metal plate with cut-outs for the laser beam can also be used ("clamping frame"). The clamping force is then applied left and to the right of the weld seam and not directly from top. If the upper part is sufficiently rigid, the clamping force from left and right is also exerted in the weld seam position itself.
If the part has a closed welding contour, it can only be clamped with an frame from the outside. The use of inner clamping jaws with a connection to the outer frame would interrupt the laser beam. If in such a case inner clamping jaws are necessary, the inner and outer clamping jaws need to be connected via a clamping glass above.