10 Things to Consider When Buying Induction Hardening Machine

31, Mar. 2025

 

10 Considerations When Selecting an Induction Heating System

Induction heating has considerable advantages over other common heating methods in specific applications. Is yours one of those applications?

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Induction heating offers many benefits to manufacturing processes because it is a rapid, energy-efficient, flameless method of heating electrically conductive materials. A typical system involves an induction power supply, workhead with a copper coil and a chiller or cooling system. Current flows through the coil to create an electromagnetic alternating field. When a conductive part is placed inside the coil, current is induced to run through it. Current flow combined with the resistance properties of the conductive part results in heat generation.

10 Selection factors to consider

 Your Part’s Material

Induction directly heats conductive materials such as metals. Nonconductive materials are sometimes heated with a conductive susceptor. Due to hysteresis, magnetic materials are heated more easily than nonmagnetic materials; consequently, nonmagnetic materials often require more power. Metals with high resistivity like steel heat quickly, while low-resistivity metals like copper or aluminum require more heating time.

Depth of Heating Penetration

The induced current will be most intense on the surface of your part. In fact, more than 80% of the heat produced in the part is produced on the “skin,” or surface. Consequently, larger parts and parts that require through-heating take more time to heat than those that are thin or small.

Operating Frequency

Lower-frequency, higher-power systems are generally suited for heating larger parts that require through heating. Lower-power, higher-frequency systems are often the right choice for surface heating. As a general rule, the higher the frequency, the shallower the heating of the part.

Applied Power

The output power of your induction heating power supply determines the relative speed at which your part is heated. The mass of the part, rise in temperature and heat losses from convection and conduction need to be considered. Often, the induction equipment manufacturer can help you make this assessment.

Rise in Temperature Required

Induction can generate a significant change in temperature, but, generally speaking, more power is needed to accommodate a significant temperature change and will impact your power-supply choice. The rate of temperature change also affects your power-supply choice. The faster the rate of change, the more significant the power requirement.

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Coil Design

Your coil, which is generally water-cooled and made of copper, needs to follow the shape of your part and take the variables of your process into account. An optimal coil design will deliver the right heat pattern to your part in the most efficient way. A poorly designed coil will heat your part more slowly and deliver an improper heating pattern. Flexible coils are now available and work well with large parts and unique part geometries.

Coupling Efficiency

The part being closely coupled with the coil elevates the flow of current, which increases the amount of heat generated in the part. Coupling enables faster and more efficient heating, which can increase manufacturing efficiency. Poor coupling has the opposite effect.

Your Facility and the Footprint

Induction requires cooling from a chiller or cooling system. Lower-power systems generally require a compact water-to-air heat exchanger, while a higher-power system may require a larger water-to-water heat exchanger or chiller. Additionally, you will need space for the induction heating power supply and workhead. Generally speaking, an induction system will save considerable space over an oven, especially when you consider that the workhead can be placed a significant distance away from the power supply. Of course, you also need to be sure your facility can handle the amount of power the system requires.

Additional Heating Requirements

Will you need to measure and store heating data? Some induction solution providers can offer a full system that includes an optical pyrometer and temperature-monitoring software so such data can be recorded and stored. A comprehensive solution can lead to a smooth installation and start-up.

Industrial Expertise

Many induction manufacturers have expertise with certain applications, and if they’ve worked with your application, it will provide peace of mind. Additionally, some providers offer laboratory testing and a tailored system recommendation based on your heating requirements. This type of service takes the guesswork out of selecting a system and helps you account for the aforementioned factors.

In conclusion, induction heating has considerable advantages over other common heating methods. Buying the right system for your application’s needs and ensuring it meets any needs you may have for it in the future will help your company fully benefit. 

Ten Things to Watch for when Buying an Induction Heater - Ludeca

When looking for an induction heater, below are some recommendations to help with your buying decision:

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  1. Size: Choose bearing heater based on maximum workpiece weight, or minimum inner (ID) and maximum outer (OD) diameter.
  2. Temperature control, single or dual: One temperature probe minimum, but two is ideal. To monitor the temperature of the bearing or workpiece a temperature sensor is required. For precision bearings, use an induction heater like the SURETHERM which features two temperature probes to accurately monitor the difference in temperature between the ID and the OD in order not to exceed the bearing’s maximum temperature differential requirements, thereby ensuring 100% tension-free heating.
  3. Automatic Demagnetizing: The process of induction heating magnetizes the bearing or workpiece, therefore an automatic demagnetizing cycle is essential in order to leave no residual magnetism that would cause debris to adhere and accumulate on the bearing.
  4. Multiple crossbars: Different workpieces have different ID sizes, so having the proper size yoke or crossbar is necessary for efficient heating of the workpiece. Always choose the largest crossbar that will fit through the bore of your workpiece.
  5. Automatic temperature hold-mode: Holding the desired temperature when reached is essential since you are not always ready to install the bearing when the heating cycle has concluded. Let the bearing wait on the person, and not the person on the bearing.
  6. Timed heating mode: If heating identical bearings one after the other in a production environment, timed mode will be faster and more efficient than temperature mode.
  7. Delayed start time (safety): Allows the user enough time to step back from the heater before it starts heating, in case the user has a pacemaker.
  8. Fail-Safe error warning: If the probe was not placed on the bearing, or falls off during the heating cycle, the heater will automatically stop in order not to overheat the bearing (if the heater is operated in either of the temperature modes).
  9. Reporting, graphing of time/temperature cycle and printing capabilities: For ISO compliance, a documentation capability to report how bearing was heated and how long it took and to which temperature the bearing it was heated would be ideal.
  10. Display temperature in degrees C or F on demand.