The pneumatic shut-off nozzle is a shut-off nozzle system that mechanically closes off melt drooling from the injection nozzle and works in sync with the machine's injection signals.
Why does drooling occur?
Raw materials with high flowability or a high gas content, especially if they have not been dried sufficiently, run out of the nozzle between shots. This is both an unnecessary loss of raw material and, because hot melt runs out in the open, an occupational safety risk. On the part it appears as stringing.
How does it work?
The standard nozzle on the machine is removed and the pneumatic shut-off nozzle is fitted in its place. The shut-off mechanism and the pneumatic cylinder are pre-mounted on the nozzle.
With the injection start and end signals it receives from the machine, the system opens and closes in sync with the machine via a pneumatic control valve. The shut-off is of the needle type; the needle closing the nozzle mechanically makes the sealing more stable.
No modification is needed to the machine body. For this reason it can be fitted to any make and model of injection molding machine.
Heat control
The nozzle is used together with thermocouples and heater bands. Because the temperature of the nozzle zone is kept under control, the melt is prevented from freezing in the nozzle or overheating and burning.
An alternative to the machine maker's solution
Injection molding machine manufacturers also offer shut-off nozzle solutions; however, these solutions often require a high investment and additional work on the machine. Because the pneumatic shut-off nozzle is an independent system fitted in place of the existing nozzle, it does the same job at lower cost and with easy installation.
If you do not want to set up a compressed air line or a signal connection, the spring-loaded shut-off nozzle, which needs no external actuation, is a simpler option. For other types, see the Nozzle System page.
