Gas Injection

Based on a high-precision measurement of the propellant gas mass flow combined with superimposed control loops, SIEBE Gas Injection (SGI) can provide every user in the cable industry with the optimum solution.
The high reproducibility of the foaming process and the exact control of the product dimensions, the capacity and the foaming rate in the ongoing production process guarantee excellent product properties and reduce start-up times and losses to a mere fraction of those of conventional processes.
The low-maintenance gas injector is optimally suited for all dosing quantities and remains in the extruder cylinder even if the gas dosing is inactive (solid production). The main propellant gases used are nitrogen N₂ (SGI-N) and carbon dioxide CO₂ (SGI-C), but argon can also be added with SGI to the molten plastic without any problems.
The modular and compact design of the gas injection (SGI) with control unit enables retrofitting into existing cable extrusion lines. 

  • Foaming rate up to 60% for N₂ and >80% for CO₂
  • Optimum reproducibility of the foaming process
  • Homogeneous, fine-celled foam structure
  • No contamination from chemical propellants
  • Can be retrofitted into existing foam systems
  • Suitable for all thermoplastics
  • Integration in system control SPCS
  • Process reliability due to easy-to-read display instruments
  • Self-monitoring and self-optimization
  • Insulation against ambient temperature fluctuations
  • Easy handling and maintenance through filter change during the ongoing process
  • Low maintenance
PLC SIEMENS SIMATIC S7 with handheld terminal
Propellant N₂ / C0₂ / Ar
Dosing pressure 75 - 350 bar
Preliminary pressure 25 - 50 bar
Gas flow rate 0,5 - 10 in/min according to customer request
Control variable Gas flow rate [I/min]
Accuracy s1 % of the setpoint value
Response time approx. 30 s
Gas supply Pressure bottles / Tanks / Factory networks / Generators