annealing with induction heating of stainles steel tube

Objective: A customer in the automotive industry is looking for an induction system for annealing and thread rolling of stainless-steel tubes.

Parts that have to be annealed with induction heating are stainless steel tubing. We received a cut sample with dimensions 1’’ OD x 1.50” long x 0.11” wall (2.54 cm x 3.81 cm x 0.28 cm). The target productivity rate is between 10-20 seconds per heat cycle.

The main goal that we have to achieve is to prove a soft annealed of the several temperature cycles. That will allow easy forming of the part in the next step of the process.

Industry: Automotive & Transportation

Equipment: For this application, we used the compact UltraHeat SM 5kW induction heating system with 6 turns helical coil.

Process: To confirm the exact temperature of the process we heated samples at 1500, 1600, 1700, 1800, and 1900°F (~815, ~871, ~927, ~982, ~1038°C). The full anneal temperature is close to 1900°F, so the customer could be evaluated which is the perfect temperature for their needs.

All temperatures were reached within 30 seconds of applying max 5 kW power. The control loop was closed with a temperature input from the pyrometer to avoid overshooting the target temperature.

Benefits: An inductor that is custom designed for this application is recommended. The coil must cover the length of the part and this should even out the heat distribution. With a custom inductor and the right settings, annealing could be automated and the heat cycle reduced.

Reference Info: Application Note 3463-7178

Read more about other induction annealing applications.

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