Electric heating wires and their industrial applications

Table of contents

Electric heating wires function through Joule heating, whereby electrical current is converted to heat through resistance. The heat is then conducted to the object being heated either through conduction, convection or radiation. Our heating wires can withstand up to 1200°C and are made of a resistive nickel-chromium alloy: NiCr8020 Electric heating wires offer a number of advantages in a range of heating applications.

Benefits of electric heating wires

Electric heating wires facilitate highly precise, efficient and rapid heating processes which can be accurately and consistently controlled. NiCr is used at high temperatures it produces an outer layer of chromium oxide which offers thermodynamic stability in air and makes the wire impervious to oxidation. Furthermore resistive electric heating wires offer flexibility of design.

All these beneficial properties make resistive heating wires suited to a variety of industrial applications. in this article we will look at their use in:

Cartridge heaters

A cartridge heater is cylindrical and specifically shaped to fit into a hole to provide very precise and localized heating at high temperatures. They are valued for being durable and low maintenance.

Function and design

A cartridge heater consists of a resistive heating coil (electric heating wire) combined with a ceramic or metal sheath and mineral insulation. Cartridge heaters are inserted into drilled holes so as to provide a snug fit for direct and efficient heat transfer – often for the heating of metal parts from the inside. It has both commercial and industrial applications and can be customized to a specific watt density based on what the particular application requires.

How are electric heating wires used in cartridge heaters?

The electric heating wire is the core source of heat in the cartridge heaters. The wire is wound around a ceramic core at a length and thickness required to meet the required resistance value of the heater.

An overview of industrial applications of cartridge heaters

In all these applications, the reliability and quick response time of the cartridge heaters make them a popular choice.

ApplicationFunction
Heating gasses and liquidsAs an immersion heater for chemical solutions and water. Preventing condensation in control panels by regulating the air temperature.
MoldingEnsuring exact mold temperatures in rubber and plastic (injection) molding.
Packaging industryFor keeping to exact sealing temperature specifications (eg for blister packs). They are also used to heat the blades ensuring clean cuts.
Medical and laboratory equipmentE.g. for analytical instruments such as gas chromatography. Also for the stable temperatures required in the equipment used for sterilization, incubation and chemical reactions.
Food processingOvens, deep fryers and grills. Their hygiene makes them a preferred choice in the food industry.
Semiconductor industryCartridge heaters offer the precision and  controlled heating that is required in various semiconductor  applications e.g. deposition and etching, metrology and lithography.
AerospaceIn aircraft engines they are used in fuel nozzles and combustion chambers. Furthermore they are essential in maintaining cabin temperatures.

Defrost heaters

A defrost heater is designed to prevent the build up of frost and ice on coils and other essential components in refrigeration systems (fridges, freezers, air conditioners) as well as in heat pumps. The heater functions at specific intervals to melt any accumulated frost.

How are electric heating wires used in defrost heaters?

Electric defrost heaters consist of electric heating wires inserted into the evaporator coils or installed along them. They are strategically placed in areas where frost and ice accumulate. For example during the defrost cycle, refrigerant flow to the evaporator is interrupted and the defrost heaters are activated, melting the ice accumulated during the refrigeration cycle.

There are two types of defrost heaters:

  • An electric resistance heater generates heat through the NiCr resistive wire element. The heat is transferred to the evaporator coils.
  • A glass tube and coil defrost heater is designed with the NiCR resistive wire transferring heat to a conductive glass tube which then warms the evaporator coils.

Defrost heaters application and advantages

ApplicationBenefit
Home, commercial and industrial fridges and freezersDefrost heaters melt ice and frost on the coils and evaporator pans. This is not only important for ensuring energy efficiency but is also critical for the temperature consistency required for food storage.
Air conditioning unitsIce build-up reduces efficiency and thus a defrost heater is important to lower energy consumption.
Heat pumpsIn cold weather conditions, frost on the outdoor coils can reduce the performance of a heat pump. Defrost heaters ensure that the pump operates effectively at any temperature.
AviationDefrost heaters can be used to keep aircraft windscreens free of ice ensuring clear visibility. Another use is in keeping pitot tubes and pitot static tubes frost free. These are air pressure, altitude and speed sensors situated on the wings and/or nose of a plane. They  provide essential data to the pilot.

Sheath heaters

Electric heating wire is a component of sheath heaters (also called tubular heaters). Sheath heaters are known to be economical and reliable in performance, supplying high temperature heat with a very quick response time. They supply heat by conduction, convection and radiation. The metal sheath can be bent, welded, soldered or cast into a metal block. These factors make it an extremely versatile heating solution. The sheath material is usually stainless steel such as Inconel which has excellent corrosion resistance.

How are electric heating wires used in sheath heaters?

A heat generating core (our NiCr80/20 resistive wire) is placed in a metal (stainless steel) sheath and tightly packed with inorganic insulation powder. This ensures that the electric heating wire is completely insulated – important for both a longer lifespan and more efficient heat transfer. Unlike cartridge heaters which are inserted into holes inside a device, sheath heaters are attached to tanks and vessels or can be immersed directly into liquids.

Applications and benefits

Sheath heaters are typically chosen for applications where superior heat transfer is required. That can be air, liquids or metals. Applications include:

ApplicationBenefits
Heating industrial process fluids such as water, chemicals and oil in the chemical and oil industries e.g. tank heating.The variety of sheath materials available makes a sheath heater adaptable to a broad range of substances. They offer the great advantage of being shaped to a specific application. The integration of temperature controls allows precise measurements.
In food processing plants.Sheath heaters are found in heat exchangers, reactors and distillation columns. They are safe to  use in explosive atmospheres.
Commercial and industrial HVAC systemsSheath heaters can warm the air throughout a structure
Industrial drying, curing, and annealing  They function well at high temperatures and distribute heat evenly and efficiently.
Heating for medical and analytical equipment.With integrated temperature sensors sheath heaters offer advanced heating control, excellent temperature maintenance and precision heat transfer.
Wastewater treatment plantsSheath heaters help maintain the temperature for the treatment process to happen efficiently. As they ensure a rapid heating process, they also offer energy savings.

Band heaters

Our electric heating wires can also be used in band heaters. These are ring-shaped devices, designed for external heating of cylindrical surfaces to which they have been clamped. Heating takes place primarily by conduction and also through radiation.

There is a huge range of band heaters, primarily characterized by the types of insulation in which the NiCr80/20 resistive heating wire is built.

Benefits of band heaters

Advances in technologies have created complex products with increasing demand for precise heating control of components. Band heater benefits include:

  • heating efficiency
  • flexibility (dimensions, insulation)
  • durability
  • excellent thermal conductivity
  • even heat distribution
  • rapid heating
  • reliability even at high temperatures

 Common uses for band heaters

ApplicationFunction
Plastics manufacturingAt the molding stage, band heaters are used to shape the plastic. Band heaters ensure the exact temperatures needed for proper softening of materials in order to allow accurate shaping.
Metal castingUsed for heating molds and keeping casting tools at the required temperature for pouring the molten metals.
Chemical processingDrum band heaters maintain the correct temperatures of the chemicals. They are essential in order to help in heat transfer, viscosity reduction,  and keeping liquids in their liquid state.
PackagingBand heaters often have a function in shrinking and sealing packages which helps make sure items are secure for shipping. The quick heating efficiency means that the parcel facility is able to process multiple packages. 
Industrial heatingBand heaters are easy to install and flexible in and shape composition. Band heaters prevent freezing in storage tanks, reactors, pipes, and processing tools.
Food productionBand heaters in food production plants are essential for both heating a mixture and maintaining the required temperatures. This process is essential for achieving the correct consistency and flavor of foods as well as for allowing even heating throughout the process. 
PharmaceuticalsSimilarly to in the food sector, the primary role of band heaters in pharmaceutics is to provide precise temperature control. This is important to prevent contamination and for the  correct consistency of mixtures during processing.

Industrial furnaces

Nickel Chrome heating wires have stood the test of time as heating elements in industrial furnaces since early in the 20th century. They offer excellent mechanical properties in the hot state and can be used at a continuous operating temperature of up to 1200°C.

What is an industrial resistance furnace?

Industrial resistance furnaces are a type of oven often used for the heat treatment of metals and pottery. Heat is generated using resistive heating wires such as our NiCr80/20 resistive wire

How are resistance wires used in furnaces ?

The furnace design includes resistance wires in the heating chamber which are connected to temperature sensors and control systems. When an electric current runs through it, the wire becomes energized, generating high temperatures. Insulation materials ensure that this heat remains in the furnace cavity where temperature sensors monitor the heat and transmit the temperature signal to the control system. The control system in turn adjusts the current and voltage of the resistance wire to match the temperature parameters of the furnace.

Kamet and our Silver Kohki electric heating wires

Kamet has partnered with Silver Kohki to offer a wide range of NiCr80/20 heating wires with a design and quality that match the precision and control demands of all the applications mentioned in this article. The wire is characterized by very stable ohmic values and exceptional performance in high-temperature environments. Our electric heating wires

Kamet’s service team is available to you for any questions you have about using our electric heating wires in your particular applications.