Annealing

Modern induction heating provides many advantages over other heating methods and is commonly used for annealing applications such as copper pipe bending. Heating through induction provides reliable, repeatable, non-contact and energy-efficient heat in a minimal amount of time without the use of flame or torch. Solid state systems are capable of heating very small areas within precise production tolerances, without disturbing individual metallurgical characteristics.

Induction can be used for either surface or through heating; case annealing is possible depending on time, temperature and the material's characteristics.

The degree of temper depends on the material, the maximum temperature reached and the length of the cool down time. Process or Stress Relief Annealing is used to negate the effects of cold work; that is, to soften and increase the ductility of a previously strain-hardened metal. Internal stresses may develop as a result of plastic deformation processes such as machining or grinding, non-uniform cooling in a welding or casting process, or a phase transformation. Distortion and warping may occur if the internal stresses are not removed. Annealing will eliminate these stresses when the part is heated to the recommended temperature, held there long enough, and slowly cooled to room temperature.

Closed loop control, through the use of an optical pyrometer or other temperature sensing device, can provide constant heat with a tolerance as low as 3°C at 700°C. Induction heating also ideal for in-line production processes because of its ability to produce repeatable, rapid and accurate heating cycles.

Induction systems typically used for induction annealing range from 1 to 20kW, depending on the parts and application requirements.