Coil heaters have been introduced to the hot runner system - greatly increasing the cycle speed and the quality of the product produced. Due to an even heat around the nozzle body, the material is not subject to excessive temperature changes,

resulting in less degradation of material. When replacing a coil heater, consider these points:
1) The profile of the heating element. A flat or square cross section is far superior to a round profile. This is because of contact - greater contact provides for easier nozzle control and faster recovery time. With a round profile-heating element, the only contact is at the zenith of the arch. But with a flat profile, the contact is across the entire surface of the heating element. A special manufacturing process is required to obtain this contact with the nozzle.

2) The correct pitch of the coil heater.> To achieve an even pitch across the nozzle, the coil heater needs to be wound tight at each end and spaced in the middle. This allows the heat to re-disperse over the nozzle, allowing for custom profiling and ensuring even temperatures across the flow channel.

3)Internal thermocouple location. The internal thermocouple should be located as close to the tip as possible.

4) The thermocouple junction. The unit must be spec'ed out to match the controller being utilized.

5) The coil I.D. The coil I.D. should be smaller than the nozzle O.D. in order to achieve a good contact. For front load systems, a pressed-on or pushed-on sheath design is recommended if a clamping strap is too large to install.

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