Welding technology at GEMÜ

28.07.2022

Welding technology at GEMÜ

At GEMÜ in Emmen, we use the laser welding and ultrasonic welding processes. This means that we have optimum solutions at hand for our customers from the medical technology and in the fields of valve and process technology.

Ultrasonic welding

Ultrasonic welding is suitable for thermoplastics, including GEMÜs injection molded parts that need to be joined together. In ultrasonic welding, ultrasonic waves in the range between 20 -70 kHz are generated by the ultrasonic generator.

A converter transforms the electrical high-frequency oscillation into a mechanical longitudinal oscillation, which is amplified by a transformation piece to the plastic-dependent welding amplitude.

This vibration hits the sonotrode (horn), which forms the contact piece to the plastic. The sonotrode (horn) transmits the vibration into the component. Its molecules are vibrated, which leads to frictional heat. As a result, the material heats up and begins to melt. By additional pressure and a holding time, the heated seam is sealed and cooled.

Ultrasonic welding is energy-saving, high-precision, resource-saving and produces finished robust welds. In addition, it enables welding regardless of the color of the components, which offers enormous flexibility in the design-making.

Laser welding

The use of a laser beam enables high-precision welds without additives in the plastic. In laser transmission welding, two plastic components are welded under pressure by laser. The laser beam with a wavelength of about 1980 nanometers is focused on the welding level by the scanner optics. In the scanner optics there are two mirrors that direct the laser differently and can thus image a wide variety of welding contours. This enables non-contact welding of the components without particles forming during the welding process.

The laser first "radiates" the upper joining partner and is absorbed by the lower joining partner, whereby its molecular chains are set in motion, thereby heating up and beginning to melt. The heat introduced is transferred to the upper joining partner under pressure, resulting in a weld seam.

In order of making laser transmission welding work, the laser beam may only absorb in the lower joining partner. As a rule, this is done by coloring the plastic using additives. The so-called ClearJoining process also enables GEMÜ to weld two transparent plastic parts without the usage of additives. Thus, the plastic remains in its raw state and classifications such as USP 6 are preserved.

This is particularly important in the manufacture of our products for medical technology and our single-use valves.