The Principle of Induction Hardening: Induction heating surface hardening is a kind of heating treatment technology about using electromagnetic induction, skin effect, eddy current, electric resistance heat and other eletromagnetic induction principles to make the surface of the workpiece be heated and cooled rapidly.
When the surface is hardened by induction heating equipment, the workpiece is placed in a sensor made of copper tube. When the alternating current of a certain frequency passes through the sensor, the workpiece surface that is placed in the alternating magnetic field will pruduce inductional current(eddy current). The eddy current makes the steel atoms and iron atoms in the workpiece move irregularly. Then these atoms collide and rub together and produce heat energy. Finally, our workpieces can be heated.
The principle of Flame Hardening: Flame surface hardening machine sprays the flame of a mixture gas of acetylene & oxygen or coal gas & oxygen onto the surface of the parts and heats rapidly. When temperature reachs the quenching degree, it cools the workpiece through spraying water or emulsified liquid. The deepth of hardening layer is generally 2-6mm. If the layer is too deep, it will make the part surface be too hot and cause quenching crack.
Advantages of Induction Hardening that is compared with Flame Hardening:
1. The working speed of induction hardening machine is extremely high. Even it only needs several seconds. The martensite structure of quenching layer is small and has good mechanical properties.
2. Induction heater's surface is not easily oxidation and decarbonization. Its deformation is small and the deepth of quenching layer is manageable.
3. Surface hardness is higher 2-3 HRC than general quenching. Meanwhile, it has lower brittleness.
4. The workpiece after induction hardening has higher fatigue resistance and impact toughness.
5. Induction heating macine's installation, operation and maintenance is easy to learn and it don't need complex training.
6. Induction hardening machine can achieve mechanization and automation easily. So it has a high productional efficiency.