The heart of the TOSS hot-air sealing unit is the air heater. A tubular heat conductor is equipped with combined connections at its ends for electric power as well as air supply. Along the heated tube body a number of bores is drilled. Electrical current flowing through the conductor will heat up the tube as well as the air passing through it. A precise temperature control will be obtained by changes in electrical resistance of the conductor (PIREG® temperature controller). This low-inertia and sensor-free kind of control will allow significantly short warm-up times (< 2 s). Use of compressed air has a positive effect on the sealing seams, also the fan and heating coil being customary with conventional solutions become unnecessary. The system is completely resistant to compressed air outages. As a substitute for the longitudinal sealing bar of tubular bag machines, the device has to be located close to the format tube (see illustration).

The heating element support is mounted on a single-acting pneumatic actuator serving as a stopping device, which will, when pressurized during operation process, bring the heating element to film. In case of a machine’s stop the heating and compressed air supply will be deactivated and heating tube will be lifted up in order to reduce the influence of residual heat to film. Travel distance of this pneumatic actuator can be restricted by an adjusting nut accessible from outside.

For short breaks or for intermittent operation an interruption of the compressed air supply will be sufficient.

A short distance between the hot air tube and the film will be resulting in the highest effectiveness, while at the same time a direct contact strictly will have to be avoided, as otherwise plastic deposits on the tube will develop. The operation of hot air sealing units requires dry and filtered compressed air of 4 to 6 bars.