Shrink Fitting

Shrink fit Teflon insulation onto a wire by heating a stainless steel pipe as a susceptor using induction. The target shrink-fitting temperature is 660°F (350°C) and overheating of the inner wire must be prevented to achieve a uniform shrink-fitting of the insulation.

SM2/200 Power Supply with Thermocouple
HS-8 Heat Station
Ultraflex 3-turn induction coil

Stainless steel pipe
Fixture for the stainless steel pipe
Wire, 0.035 in (0.014 cm) diameter
Teflon insulation

Key Parameters
Temperature: 660°F (350°C)
Power: 0.4 kW
Time: 35 secs.


  • The stainless steel pipe will be used as a susceptor to heat the Teflon insulation around the wire.
  • A simple fixture to hold the stainless steel pipe was made to prevent the wire and insulation from touching the hot surface of the pipe.
  • The thermocouple was attached to one end of the tube and to the induction generator to use the generator’s thermo-regulation.


  • Initial heating with thermo-regulator parameters:
    Power set: 20%
    Temperature set: 660°F (350°C)
    Temperature zone: 390°F (200°C)
    Temperature offset: 75°F (24°C)
  • Feed and move the wire through the heated susceptor (the stainless steel pipe).


  • Main objective of the test was achieved.
  • The Teflon insulation is shrink-fitted with high quality, and the wire is not damaged by the process.


  • 2 kW air cooled unit is suitable for the process.
  • The Teflon insulation can be heated from the “outside” using controlled process.



Request information or contact us about this application. Reference info: Application Note 3464-4593.