Clamping jacket for GC-coil coil heaters

State of the art

State-of-the-art clamping mechanisms are designed to ensure that coil heaters remain firmly clamped to hot runner nozzles. However, the majority reach their limits pretty quickly: the material loses its stability under extreme temperatures and expands, causing the coil heater to uncontrollably detach itself from the nozzle. This creates pockets of air between the heating element and the nozzle, which makes it impossible to keep the temperature even and can very quickly lead to the complete failure of the coil heater due to overheating. In addition, screw connections, tension clamps or the complete moulding of the heating element mean that many of these clamping mechanisms also require a great deal of space, which is not available in standard hot runner moulds with little cavity spacing. The GC-jacket permanently holds and clamps and is basically a slotted metal tube that firmly clamps the GC-coil coil heater onto the cylindrical hot runner nozzle at temperatures of up to 550 °C. The material properties of the GC-jacket, together with its thin-walled design, easily and effectively solve conventional clamping mechanism problems.

Technical details and properties

  • The self-clamping nature of the GC-jacket alone means that the heating element is firmly pressed onto the nozzle. Its clamping span enables it to adapt to the diameter tolerances of the heating element. Once clamped, the GC-jacket guarantees vibration-proof and shockproof pressure, making any re-clamping unnecessary
  • The extremely high creep rupture strength of the material, also under extreme temperatures (>10000 h at 550 °C), guarantees the continuously firm pressure of the GC-coil coil heater on the nozzle for a considerable length of time
  • The permanent pressure ensures a constant thermal coupling of the heating element and the nozzle. This enables maximum heat transfer with uniform temperature control
  • Due to the low mass of the GC-jacket compared to copper or brass embeddings, thermal reactions are very fast for precise temperature control. Furthermore, since no heat exchange can occur in the nozzle heating system, a much more systematic power and temperature distribution on the nozzle is possible
  • The thin-walled design of the GC-jacket (wall thickness 0.5–3.2 mm, depending on nozzle diameter and length) permits tight cavity spacing even with compact moulds
  • Due to the structural slot which runs across the entire length of the GC-jacket, the attachment of a separate surface thermocouple is possible, without increasing the outer diameter
  • The thermal dissipation of the heating element is considerably reduced by reflecting the heat radiation
  • The GC-jacket is reusable
  • The GC-jacket is highly resistant to corrosion
  • The GC-jacket is available for all GC-coil diameters