Induction Heating Equipment for Shrink Fitting

Shrink fitting with induction equipment from eldec LLC

Shrink fitting using induction heat simplifies assembling and disassembling metal parts. The process is quick, and the joints are neat and precise. Gentle, non-contact heat expands the outer mating part evenly without negatively affecting the microstructure, while the inner part is inserted at ambient temperature.  As the outer component cools it creates a firm bond. A thermoelectric device on the generator measures the temperature and creates a setpoint level of heat that cannot be exceeded, which protects the parts from overheating in some areas and not heating enough in other spots.  A similar process can be used to remove a mated component for repair or replacement.

At eldec our technicians will review your parts, select an appropriate induction power supply and design custom inductors specifically for your components, ensuring top rate efficiency and quality joints. They can also help setup the perfect recipe of generator settings – setpoint temperature, length of time, energy level and magnetic frequency – to fit your production situation.

Induction shrink fitting systems and processes

eldec manufactures two lines of robust, medium frequency induction generators that are appropriate for shrink fitting and de-coupling component parts, the ECO LINE and the CUSTOM Line. These two lines of power supplies are often used in manufacturing operations for automotive, aerospace, oil/gas production and distribution, power generation, medical device industries and more.  Additionally, our experience with custom manufacturing induction heating coils as well as processes used in a variety of industries make us a valued supplier of induction shrink fitting systems.  Don’t take our word for it. See how Elektror airsystems, a manufacturer of industrial fans, updated their aging induction system with a safer, more efficient one from eldec. In this video they explain how the new eldec induction system improved their ability to connect a stator housing with a motor winding.

Common applications for induction shrink fitting

Induction can uniformly and gently heat the outer portion of a motor housing or the ID of a bore without overheating or damaging any one area, making shrink-fit connections fast and simple to assemble and disassemble. This non-contact process is precisely controlled and traceable, and can be adapted for:

  • Joining electric motor housings
  • Joining motor shafts and rotors
  • Replacing or aiding in press fit processes
  • Gear insertion
  • Helping to maintain concentricity of components being assembled
  • Other interference fit assembly applications

Induction heating benefits for joining and separating

Precise and speedy connections are the main advantages of using induction for shrink fitting component parts; however, the following list provides an idea of additional benefits:

  • Energy efficiency – place heat where you need it and avoid heating unnecessary areas
  • Consistent and uniform heat – no heat spikes or cold spots
  • Operator safety – no flame means operation in tight spaces or volatile environments are less risky
  • Heat on demand – rapid availability of heat means less time to reach the desired temperature as well as shorter cool down times

Induction shrink fitting is ideal for electrical motors and pumps

Induction heating makes shrink-fit connections simple to assemble and disassemble by uniformly and gently heating and expanding the outer component of the assembly without overheating any one area. Since an induction generator’s output power can be controlled via a thermocouple or pyrometer, the generator can control the process to regulate and limit a component’s temperature automatically. This control ensures that an established set-point temperature is not exceeded.

Example 1
The induction coil is an ID heating coil placed within a housing

In figure 1 of our example, a motor housing is uniformly heated in order to expand for assembly without negatively affecting the microstructure. In this case, the induction coil is an ID heating coil that is placed inside the housing. The thermal image in figure 2 shows a typical heat distribution pattern in a motor housing heating application.

Example 2
The coil is built to heat both the ID and the OD of the rotor simultaneously

Figure 3 shows another rotor ready to be heated by a scanning induction coil. In this instance, the coil is designed to heat both the ID and the OD of the rotor at the same time. By allowing the coil to scan along the length of the rotor, the same coil and tooling setup can be used for rotors of multiple lengths, provided they all have the same inner and outer diameters.

Example 3
Two housings can be shrink-fitted in rapid succession

In addition, an eldec EMAG animation demonstrates how an eldec induction system can be configured with automation so that two housings can be shrink-fitted in rapid succession. Using a conveyor system, the dual station could be integrated with a larger production cell. Watch the animation below.

Induction heating power supplies and coils for small to mid-size electric motors

When manufacturing small to mid-size electric motors, eldec recommends using:

  • ECO LINE medium-frequency generators (MFG)
  • Custom manufactured inductors

eldec’s medium-frequency generators (both ECO and CUSTOM LINES) have a wide variety of configuration options that can be matched to specific applications for electric motors and generators including (but not limited to):

  • Joining electric motor housings
  • Joining motor shafts and rotors
  • Short circuit ring brazing
  • Other brazing applications

These powerful and robust induction generators are available in the ECO LINE with power ratings ranging from 5 to 150 kW and frequencies from 8 to 40 kHz. All medium frequency ECO LINE generators may be built standard with a Power Boost feature that allows operators to over-dive the 100% continuous duty rating by an additional 50% for up to three (3) minutes. Strengths include igbt transistor technology, precise energy dosing and an efficiency rating of over 90%.

Virtually maintenance free, ECO LINE medium-frequency generators operate quietly, take up little space and can easily be integrated into a cell controller thanks to a standard high-speed PLC and multiple control options. In addition, the generators are available with single output or multiple output transformers. These connection options allow energy to be delivered sequentially (one side at a time), simultaneously (power provided in parallel and individually controlled), or symmetrically (power provided in parallel and working together, not individually controllable).

Induction heating power supplies and coils for large electric motors

For larger, industrial electric motors eldec recommends its CUSTOM LINE medium frequency generators, which are built with power ratings up to 500 kW and larger. eldec’s CUSTOM line generators provide tailor-made answers. Each device is configured for the specific process, and a huge range of options are available, including single or multiple outputs and a wealth of power and frequency combinations.

 Advantages include:

  • High efficiency ratio
  • Precisely controlled application of energy
  • Wide frequency, power, and adjustment ranges
  • Maintenance free
  • Easy operation
  • Extensive interface package
  • Wide range of multiple power outputs

Leading manufacturer of induction heating equipment for your shrink fitting application

eldec is a shrink fitting equipment manufacturer. If you are looking for the right generator to couple and uncouple components in a shrink fitting application, we’d be happy to assist you in the early stages of a project to pinpoint the best solution for you.  Our technicians have years of hands on experience and access to a deep knowledge base to help you get the most out of your induction heating equipment. If induction is new to you or if your staff needs help getting up to speed, we also provide operator and maintenance training.

At eldec every project, including process analysis, begins with a consultation with our knowledgeable application engineers. Call us or send a request for consultation and learn how eldec can assist you.