Coil Heaters - Knowledge Compendium

Marcin Napierała

September 9, 2025

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5 min czytania

Coil heaters are an essential component in many industrial equipment and processes. They are often used where band heaters prove to be insufficient or where there is no technical possibility to install them. Coil heaters are used, among others, in injection molding equipment (injection molding machines), packaging equipment, medical equipment or in the production of semiconductors. Today we will try to get closer to how coil heaters are built and what are the basic principles of their operation.

What is a coil heater?

A coil heater is a type of heating device that uses a resistance wire wound in the form of a spiral with a circular cross section. The wire is usually found in a jacket made, for example, of stainless steel. This covering material provides an additional insulating and protective layer.

Coil heaters — the most important advantages

What makes coil heaters Are they so widely used in modern industry? There are several reasons for this popularity. The most important advantages of coil heaters include:

High performance — Coil heaters are very efficient and reach the set temperature extremely quickly. These are often high-power heaters.
Flexibility — coil heaters from our offer are manufactured to order and tailored to the individual needs of the Customer. So they can be used where ready-made solutions do not work.
Easy control — the temperature of coil heaters can be precisely regulated and controlled by e.g. temperature sensors (we offer heaters with the possibility of building a thermocouple).
durability — with proper maintenance and use, our coil heaters will serve without fail for a long time.

Do coil heaters have any disadvantages? A certain drawback can be considered a relatively high energy consumption. In the place, however, we get a lot of power, which in certain situations is necessary. Coil heaters for proper operation and maintenance of optimal operating parameters also require regular maintenance. It all depends, of course, on the specific model of the coil heater. Coil heating elements are made in Sinkoplex on individual customer order. Accordingly, the technical data of individual heaters may differ significantly.

Where are coil heaters used?

Coil heaters are widely used in various industries. Here are some common examples of applications for this type of heating components.

Industrial processes related to plastics — coil heaters are often found in injection nozzles or systems using hot ducts. They allow you to maintain the plastic at the right temperature, optimal for molding.
Machines and equipment for the production of packaging — on a similar principle as in the case of injection molding, coil heaters are also widely used in industrial equipment for the serial production of packaging.
Reactors — Spiral heaters can be used in various types of reactors, including chemical, biological and even nuclear. They are often used to maintain the required temperature conditions to carry out specific reactions.
Medical equipment — coil heaters are also a component of some medical devices. This applies, for example, to devices intended for sterilization.
The production of semiconductors is a very complex process that requires constant, very high temperatures at certain stages. Their achievement and maintenance is often possible precisely thanks to coil heaters.
Food industry — simple coil heaters are also found in everyday appliances such as ovens or toasters.

These are, of course, just a few examples of sectors and industries that use coil heaters. An alternative to this type of heating elements are also often ring heaters.

The principle of operation of coil heaters

Coil heaters, as well as ceramic heaters, operate on the basis of the phenomenon of resistive (resistive) heating. When an electric current flows through a resistance wire, it encounters the resistance of the electron flow. This resistance causes electrical energy to be converted into heat energy — the greater the resistance, the more heat produced.

Spiral heaters are usually made of resistance wire wound in a spiral. This wire is usually made of a material with high resistivity and high temperature resistance. For our coil heaters, it is a nickel-chromium resistance wire thickened with high quality magnesium oxide. The wire is sheathed with a jacket made of stainless steel (AISI 304 and AISI 321 steel), which ensures protection and durability.

Types of coil heaters

Coil heaters can be divided according to their design into 3 basic types:

axial coil heaters,
tangential coil heaters,
radial coil heaters.

The differences in the design of these three types of heaters are best explained by the diagram below:

Optimal arrangement of heating zones and heater coil spacing

Coil heaters do not at all need to have an even spiral arrangement, in which individual coils are located at the same distance from each other. The pitch of the coil coils of the heater is an important design factor, providing heating adapted to the requirements of a particular project. Influence on the design of the heater is influenced by such factors as:

Heating Requirements — The specific heating requirements of a particular heater application, such as desired temperature distribution and heat transfer, play a role in determining the layout and spacing of coils.
Heated surface or object — The shape, size and geometry of the heated object or surface affect the design of the spiral heater. The coil arrangement should be optimized to achieve uniform heat distribution over the target area. Sinkoplex coil heaters are supplied in standard form or for self-winding.
Heat Transfer Characteristics — Understanding heat transfer mechanisms (conduction, convection, radiation) and the material properties of the heated object or surface helps determine the appropriate arrangement and spacing of coils.

Schematic example of a coil heater with an irregular arrangement of coils to obtain a certain distribution of thermal power:

Temperature control in coil heaters

Precise temperature control in coil heaters is crucial for most applications of these heating elements. For our heaters, we offer the possibility of mounting a temperature sensor in the form of a J thermocouple (up to 650°C) or a K-type thermocouple (up to 1000°C).

A thermocouple is a temperature sensor consisting of two metal wires connected in a loop. The temperature difference between the two connectors generates voltage, which is used to accurately determine the temperature. The output signal from the thermocouple can be used to control the power supply of the coil heater.

An alternative to a thermocouple is a thermostat. Its principle of operation is very simple. Mechanical or electronic thermostats are set to a certain temperature level. When it is exceeded, the thermostat adjusts the power supply to maintain the desired temperature.

Safety of use of coil heaters

Safety is a key aspect of the use of all types of heating elements, including coil heaters. Since these are often high-power components, it is very important to implement appropriate security measures. In practical applications, various solutions are used. These are, for example, temperature limiters. These devices cut off the power at the moment when the temperature exceeds the specified limit. It is also crucial to carefully monitor the temperature of the heating elements described a little above.