Shrink fitting of PTFE tube with a substrate inside using induction susceptor heating. Shrinking temperature is 350°C. Overheating of inner wire must be prevented.
Stainless steel pipe
Fixture for the stainless steel pipe
Guidewire with diameter app 0.035 inch (0.014 cm)
Temperature: approximately 662° F (350°C)
Power: 0.4 kW
Time: 35 seconds
Frequency: 143 kHz
- Stainless steel pipe will be used for susceptor. It will be heated by induction using temperature control of the process.
- Simple fixture for stainless tube holding was made. Thermo-couple was attached to one end of the tube. Purpose of the fixture is to prevent wire and shrink material to touch the hot surface of the pipe.
- Thermo-couple was attached to induction generator in order to use internal thermo-regulator.
- Initial heating with thermo-regulator parameters:
– Power set: 20%
– Temperature set 350°C
– Temperature zone 200°C
– Temperature offset 24°C
Preheating time is around 2 min.
- Feed and moving the wire through the hot pipe by hand
- Main objective of the test was achieved. PTFE can be heated from “outside” using controlled process.
- Heated sections of the wire seem with good quality.
- Wire doesn’t seem to be damaged.
- 2kW air cooled unit is suitable for the process.
- Custom air cooled (litz wire) coil have to be designed.
- Speed and temperature have to precised to achieve perfect results.
- Induction system:
- As a vital part of the process, feeding of the wire needs more attention.