Induction Hardening


WHAT IS Induction Hardening?

What’s Induction Hardening?

  Induction hardening is a quenching method that uses the principle of electromagnetic induction to make the workpiece cut magnetic field lines in the alternating magnetic field and generate induced current on the metal parts’ surface. According to the skin effect of alternating current, the surface of the heated part is rapidly heated in the form of an eddy current and then induction quenching quickly.

  After the induction heating machine finishes the heating and quenching process, the metal parts surface hardness is high, the core maintains good plasticity and toughness, showing low notch sensitivity, so the impact toughness, fatigue strength, and wear resistance are greatly improved. Due to the short heating time, the surface oxidation, and decarburization of parts less, compared with other heat treatments, the parts rejection rate is very low. Also choosing the suitable induction heating coil plays an important role in the field of metal induction heat treatment.

Why use the induction hardening process?

  Induction quenching is a process in which eddy currents are generated in the metal workpiece by electromagnetic induction and the workpiece is heated. Compared with common metal heating technology, induction quenching technology has the following advantages:

1. The metal workpiece surface hardness is high. The surface hardness of the workpiece hardened by high and medium frequency induction heating is 2 ~ 3 HRC higher than that of ordinary quenching.  Its metal impact toughness, fatigue strength, and wear resistance are greatly improved.  The service life of a metal workpiece can be greatly extended by induction quenching.

2. The metal workpiece is not integral heating, so with induction hardening, the workpiece overall deformation is small;

3. The metal workpiece heating time is short, the surface oxidation decarburization amount is less;

4. Heating source works in the metal workpiece surface, heating speed and efficiency is high; 

5. Induction quenching equipment structure is more compact than common metal induction heating equipment, easy to operate.

6. Induction hardening machine realizes mechanized and automatic heat treatment processing, saving labor cost.

7. Induction hardening technology in surface hardening can also be used in penetration heating and chemical heat treatment. 

How to choose the appropriate induction Hardening process?

  The induction hardening process has several heating methods and all have suitable heating workpieces.

1. One-time induction heating hardening method:

  One-time induction heating or simultaneous induction heating is the most common induction hardening method. When this method uses two rectangular tubes surrounding the workpiece surface for rotary heating, it is conventionally called a Single Shot.
  The advantage of this induction heating method is to complete all the workpiece surface area induction heating jobs at a time. Therefore, its operation is simple, productivity is high, it is suitable for heating the workpiece area is not too large. For heating the particularly large area workpiece, adopt the one-time heating method, it requires considerable power and high investment cost.

  The most common examples of one-time induction heating hardening are small and medium modulus gears, CVJ bell-shaped shell bars, inner raceways, carrier wheels, support wheels, leaf spring pins, pullers, valve ends, valve rocker arm arcs, etc. 

2. Scanning induction hardening method:

  When the workpiece heating area is large, the induction heating power supply is small, this method is often used. At this point, the calculated heating area S refers to the region contained by the induction ring. Therefore, the same power density, the induction heating machine required power is small, the compete induction hardening machine investment cost is low, suitable for small batch induction hardening production, typical examples are large-diameter piston rod, corrugated roll, roll, oil pipeline, sucker rod, rail, machine tool guide rail and so on. 

3. Subsection one-time induction heating quenching method

  Typical examples are the multiple camshafts induction hardening, each time heat one or more cams, after finish this time induction quenching, heating another cam part, the gears are hardened tooth by tooth can also be included in this category.

4. Subsection induction scanning quenching method

  Typical examples are valve rocker shafts or variable speed shafts induction hardening, where multiple parts of a shaft are scanned for induction quenching, the quenching widths may be different, and tooth by tooth scanning quenching may also be included in this category.

5. Induction heating and quenching in liquid

  Induction hardening quenching in the liquid, means the induction coil and the workpiece heating surface are immersed in the induction quenching liquid, heated, due to the heating surface power density being greater than the surrounding quench fluid cooling rate. Therefore, the surface heats up quickly. When the inductor is powered off, the surface of the workpiece is hardened due to the heat absorption of the workpiece core and the cooling of the quenching fluid. 
  This method is generally suitable for steel workpiece which requires a less critical cooling rate.  When the workpiece is placed in the air and the induction coil is powered off, the heat of the surface is absorbed by the center of the workpiece. When the cooling rate of the heated surface is greater than the critical cooling rate, the workpiece is hardened, which is similar to the quenching in the liquid.

What are the components of the induction hardening system?

  The composition of a complete induction quenching machine generally includes an induction heating power supply, CNC induction hardening machine tool, induction hardening coil, and the auxiliary cooling water circulation system and quenching liquid circulation system.
  Modern induction heating equipment manufacturers, a considerable part of the ability to undertake complete sets of induction hardening equipment and turnkey project, the user from order to shorten the production cycle, and avoided due to multiple supply department in the process of debugging is not harmonious, and the long debug ills such as time. The supply of complete equipment and turnkey projects has become a means of competition for equipment manufacturers.

  In total, As one of the leading induction hardening system manufacturers in China, we have helped thousands of heat treatment factories to find suitable induction heat treatment solutions already, so in order to make sure the suitable induction hardening system induction quenching process. You can please let me have your hardening parts drawings, material, hardness, and hardening depth requests, and we can give you the related induction heating hardening system technical suggestions along with the quotation sheets. Thanks.

Induction Hardening Quenching System Partial Application Cases

1. Inclined vertical raceway CNC induction quenching machine system

Inclined vertical raceway CNC induction quenching machine system

2. Chain Plate Induction Hardening System

Chain Plate Induction Hardening System

3. Cantilever gear CNC induction hardening machine system

Cantilever gear CNC induction hardening machine system

4. Wind Power Bolt Induction Quenching and Tempering System Production Line

Wind Power Bolt Induction Quenching and Tempering System Production Line

5. Balanced shaft shell inner hole induction heating hardening system

Balanced shaft shell inner hole induction heating hardening system

6. Large Mill Roller Induction Hardening

Large Mill Roller Induction Hardening

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