Nowadays, laser transmission welding with its range of concepts has found various fields of application. It allows for weld seams of differing width and contours to be realized in both 2-D and 3-D operating conditions. Globo-welding, a technique developed and patent-registered by Leister Process Technologies, facilitates joining of three-dimensional, freely formed component geometries without requiring an additional clamping device. The Globo-welding concept is based on an air-borne glass ball which serves both as a clamping tool and an optical device. Thus, clamping pressure is only applied where the laser radiation is taking effect. Globo-welding is also applied for large and endless 2-D elements. The concept is especially convenient for joining flexible components and is used with materials such as films, non woven materials and thermoplastic elastomeres (TPE). Endless applications can be processed as easily as individual joining geometries. Since the geometry of the weld seam can be flexibly adapted from component to component, production processes may be chaotic.
The concept of laser welding basically relies on the differing optical properties of the joining partners. Whilst one of the joining partners needs to be transparent to laser radiation, the other one needs to absorb this radiation. In the joining of films, the field of application is extended to the welding of two identical (or compatible) transparent films. This material features a comparatively higher melting temperature so as not to merge with the films. The laser beam penetrates both of the transparent films and is then absorbed and transformed into heat by the material underlayed. Due to thermal conductance, the films are heated up such as to produce melt and to be welded. The joining pressure required is applied by the Globo-optic.
Laser transmission welding following the principle of heat conductance, using a Globo-head.

For two-dimensional, small weld seam geometries it is possible to apply a conventional static clamping device.
laser transmission welding following the principle of heat conductance, using a conventional clamping device.

Depending on the material and the laser parameters in use, films of up to 100 m can be welded. In fact, the technique has been successfully applied for PU films in medical engineering as well as for PET- and HDPE- films in the packaging industry. As for the absorbing material, a black PTFE-film clad glass fabric has proved useful.