Furnace Heating Coil Selection Guide: Types, Materials & Applications

Key Takeaways

• A furnace heating coil converts electrical energy into heat through electrical resistance.
• Coil size, pitch, resistance, and installation method affect heating performance.
• NiCr and FeCrAl are common materials for different furnace conditions.
• Temperature, atmosphere, power requirements, and heating cycles should be considered before ordering.
• Custom coils can be made to match specific furnace dimensions and operating requirements.

A furnace heating coil is a resistance heating element that converts electrical energy into heat. As current passes through the element, heat is generated and transferred to the furnace chamber.

For industrial buyers, choosing a suitable coil involves more than checking the furnace temperature. Its dimensions, electrical requirements, installation space, and support method must also be considered.

This guide explains the main types of furnace heating coils, key specifications, common failure causes, and custom options.

1Key Takeaways2What Is a Furnace Heating Coil?3What Types and Materials of Furnace Heating Coils Are Available?4How Do Furnace Conditions Affect Coil Design?5What Causes Furnace Heating Coil Failure?6What Specifications Should You Check Before Ordering?7How to Order a Custom Furnace Heating Coil?8FAQ9ConclusionWhat Is a Furnace Heating Coil?

A heating coil for furnace applications is usually made from resistance wire or ribbon. The material is wound into a spiral or another specified shape so that enough heating surface can fit inside the available space.

Coil diameter, pitch, wire size, and active length can be adjusted according to the furnace design.

How Does a Furnace Heating Coil Work?

When current passes through the resistance material, electrical energy is converted into heat. The basic relationship between power, voltage, and resistance is:

P = V²/R

The required resistance depends on the power supply and target output. At the same time, coil geometry affects the final resistance and heat distribution.

Where Are Furnace Heating Coils Used?

Furnace heating coils are used in many thermal processing applications, including:

• Heat treatment
• Annealing
• Tempering
• Muffle furnaces
• Laboratory furnaces
• Ceramic and glass processing
• Industrial ovens
• Semiconductor heat treatment

For example, electric furnace heater coils can be designed for different heating zones and chamber sizes. In muffle furnaces, coils may be placed in wall grooves or mounted on ceramic supports.

What Types and Materials of Furnace Heating Coils Are Available?

Heating coils can be made in different shapes and sizes to suit the furnace design. Resistance wire and ribbon are both used for electric heating applications.

Electric and Muffle Furnace Heating Coils

Open coils are commonly formed by winding resistance wire into a helix. This design provides a large heating surface within a limited space.

Ribbon elements can also be used when a different shape or resistance is required.

A muffle furnace heating coil may be installed in grooves or fixed with ceramic supports. The element must remain stable as it expands and contracts during heating.

Nickel-Chromium (NiCr) Heating Coils

NiCr alloys are widely used for electric heating elements. They provide good mechanical strength and oxidation resistance.

They can also be formed into various coil shapes. As a result, NiCr coils are suitable for many furnaces that operate through repeated heating cycles.

Iron-Chromium-Aluminum (FeCrAl) Heating Coils

FeCrAl alloys are often used in high-temperature electric heating applications. Under suitable oxidizing conditions, an alumina layer forms on the surface during operation.

Gitane offers FeCrAl heating alloys such as 0Cr25Al5, 00Cr20Al6, and 0Cr23Al5. The suitable grade depends on the operating conditions and heating element design.

How Do Furnace Conditions Affect Coil Design?

The furnace environment directly affects coil performance. Temperature, atmosphere, and heating cycles should therefore be considered during the design stage.

Operating Temperature

The furnace setpoint does not always equal the actual coil temperature. Depending on insulation, heat transfer, surface loading, and coil design, the element may operate at a higher temperature.

For this reason, a high temperature heating coil should be designed according to the actual element temperature. The selected alloy must also be suitable for that temperature range.

Furnace Atmosphere

The furnace atmosphere also affects material and coil design. Oxidizing, reducing, carburizing, and vacuum environments can create different operating conditions for the heating element.

The working atmosphere should be provided when a coil is specified. This allows the material and configuration to be selected more accurately.

Continuous and Cyclic Heating

Heating cycles also affect coil life. As the element heats up and cools down, it expands and contracts.

If the coil is poorly supported or the spacing is unsuitable, repeated thermal movement can cause deformation. Coil pitch, support spacing, and installation method should therefore match the operating cycle.

What Causes Furnace Heating Coil Failure?

Heating coils can fail because of excessive temperature, poor support, unsuitable dimensions, or connection problems.

Overheating and Hot Spots

Hot spots may develop when coil spacing is uneven or heat is not distributed evenly.

Excessive electrical loading can also raise the element temperature beyond its suitable range. Local overheating may then shorten the service life of the coil.

Oxidation and Surface Degradation

High-temperature heating elements can experience surface degradation during operation. The rate depends on the alloy and working environment.

The element should therefore be selected according to the actual furnace conditions.

Coil Sagging and Thermal Deformation

A heating coil may gradually change shape during long-term operation at high temperatures.

Sagging becomes more likely when long sections are poorly supported or the coil dimensions are unsuitable. Proper geometry and support can help reduce deformation.

Terminal and Connection Failure

The connection can fail even when the heating element itself remains intact.

Loose connections or high contact resistance may create excessive heat near the terminal. Damaged ceramic parts or incorrect terminal dimensions can cause similar problems.

What Specifications Should You Check Before Ordering?

Before ordering a furnace heating coil, check the main dimensional and electrical requirements. These specifications help ensure that the coil fits the furnace and provides the required heating output.

Key SpecificationWhat to CheckCoil dimensionsDiameter, pitch, and lengthWire or ribbon sizeDiameter or thicknessElectrical requirementsResistance, voltage, and powerCold endsLength and connection positionSupport and terminalsInstallation and connection method

For replacement projects, an existing coil, drawing, or sample can be provided as a reference.

How to Order a Custom Furnace Heating Coil?

Standard heating elements may not fit every furnace. When the required dimensions, electrical parameters, or installation conditions differ from standard designs, a custom coil can be produced.

The coil can be designed around the available heating space and operating requirements. For replacement projects, an existing coil, drawing, or sample can be provided as a reference.

Custom Furnace Heating Coils from Gitane

When comparing heating coil manufacturers, buyers should look at more than material options. Manufacturing capability, dimensional control, customization, and experience with different furnace applications should also be considered.

Beijing Shougang Gitane New Materials Corporation specializes in electric heating alloy materials, including FeCrAl and NiCr alloys. Its products are available as wire, ribbon, and strip.

Using these materials, Gitane can manufacture and customize heating elements for different applications. Coil dimensions and material selection can be adapted to specific furnace requirements.

Custom Heating Elements for Different Furnace Applications

Custom heating elements can be developed for both replacement projects and new furnace designs. The coil can be made to suit the available installation space and required electrical parameters.

By providing the furnace conditions and existing element details, buyers can work with Gitane to develop a custom furnace heating coil for their application.

FAQWhat is a furnace heating coil?

A furnace heating coil is a resistance heating element made from alloy wire or ribbon. It converts electrical energy into heat inside a furnace.

What factors affect furnace heating coil design?

Key factors include operating temperature, furnace atmosphere, power requirements, installation space, coil dimensions, and support method.

What causes a furnace heating coil to burn out?

Common causes include excessive temperature, uneven heating, poor support, unsuitable dimensions, oxidation, and connection problems.

Can furnace heating coils be customized?

Yes. Coil diameter, pitch, wire or ribbon size, length, resistance, cold ends, and terminal dimensions can be customized to suit the furnace.

What information is needed for a custom furnace heating coil?

The furnace type, operating conditions, electrical requirements, and existing coil dimensions are useful starting points. A drawing or sample can also help the manufacturer develop the required coil.

Conclusion

A suitable heating coil for furnace applications should match both the furnace design and its operating conditions. Coil dimensions, electrical requirements, material, support, and connection design all affect performance and service life.

For replacement projects or new furnace applications, a custom heating element can provide a better fit than a standard coil. Gitane offers FeCrAl and NiCr heating alloys and can manufacture customized heating elements for specific application requirements.

Need a custom furnace heating coil? Contact Gitane to discuss your furnace requirements and develop a suitable heating element.

Runfei Steel Group was established in 1998, start with import business. It is a large-scale steel processing and distribution trading company that provides integrated procurement, sales.