• Magnetic steel wire cable 0.5625″ (14.288mm)
• Magnetic steel ferrule (tapered, 1.08″ (27.432mm) at widest point)
This hot forming steel cable application is a great fit for induction heat. For cables, there are additional factors to consider when heating with induction. If the cable was manufactured very tightly with large strands of wire, the cable may behave similar to a solid cylinder when heated; which is very efficient. However, a loosely assembled cable with small wires, will behave more like many small parts to heat. For smaller parts, higher frequency is more effective in induction heating.
In this case, the customer has a steel cable with a ferrule attached. After heating the end of the cable to approximately 2000°F (1093°C), they deform it with a hammer, which then keeps the ferrule in place. For this hot forming steel cable application, the customer wants to reduce the heating time for this process, which is currently heated with a torch. The goal of this test is to heat the end of the steel cable to 2000°F (1093°C) in a total cycle time of 90 seconds or less.
In this application we are heating above curie for the steel. Curie is the temperature where the metal’s properties change from magnetic to non-magnetic – in this case, 1390oF or 770oC. Since magnetic metals heat using induction more readily than non-magnetic metals, heating past the curie temperature affects how efficiently we can heat the metal. Post curie therefore requires more power to heat than pre curie.
Pre Curie – 0.92kW
Post Curie – 1.92kW
Time: 227 seconds to 2000°F (1093°C)
72 seconds – 1400°F (760°C)
76 seconds – 1500°F (816°C)
80 seconds – 1600°F (871°C)
104 seconds – 1700°F (927°C)
135 seconds – 1800°F (982°C)
172 seconds – 1900°F (1038°C)
227 seconds – 2000°F (1093°C)
Pre Curie – 188kHz
Post Curie – 197kHz
- For this hot forming steel cable application test, the steel cable and ferrule were in the coil so that the top of the wire was not more than 0.4 inches from the top of the coil. No part of the wire and ferrule were allowed to touching the coil.
- The induction system was turned on. Temperature was verified with Williamson Pro 90 – Dual Wavelength Fiber Optic Pyrometer.
- Using a UPT-S2 power supply, the part can be heated to 2000⁰F in 227 seconds. This does not meet the customer’s requirement of reaching temperature within 90 seconds.
- Using Using a UPT-S5 power supply, the part can be heated to 2000⁰ F in 70 seconds. This fully meets the customer’s requirement of reaching temperature within 90 seconds.
- Heat times are very dependent on the position of the load in the coil. Very small adjustments of the load will vary the heating times greatly.