Design  Engineering  Manufacture

Cartridge Heater

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What is the construction of cartridge heater?

Cartridge heater is tube-shaped heating element. The heating part is nickel-chromium heat-resistant alloy wire, wounded on a magnesium oxide core rod with excellent insulation and thermal conductivity. Between the heating wire and the outer sheath is high purity magnesium oxide powder worked as insulation. The air inside is compressed by the machine to make it into a cartridge heater.

After the main body of cartridge heater is completed, the fixing accessory or thread can be installed according to customers needs. There are many structures of the fixing accessory or thread, please contact our sales or technical personnel for the best solution.

Cartridge Heater with Ceramic End Cap
Cartridge Heater with Locating Ring
Right Angle Cartridge Heater
Steel Hose Cartridge Heater with Fixing Plate

Customer Case

Metal Molds

Fast and efficient heat transfer to help reach the desired temperature quickly without wasting time and energy.

Aluminum Heating Platform

Cartridge heater and thermocouple are integrated to achieve tempreture control.

Uniform Heater

Effectively and uniformly heat up metal plate for curving glass screen.

Main materials

Heating Wire

Ni80Cr20 Nickel-chromium wire


High purity MgO


SS304,  SS310S,  SS316,  TA1,  Incoloy800(NCF800)

Lead Wire

Silicone fiberglass lead wire (Max. Temp. 250℃)

Teflon wire (Max. Temp. 250℃)

High temperature fiberglass wire (Max. Temp. 400℃)

Ceramic beads  (Max. Temp. 800℃)

Lead Protection

Silicone fiberglass sleeve, fiberglass sleeve, stainless steel hose, stainless steel braid

Seal Options

Ceramic/ceramic glue (Max. Temp. 800℃)

Silicone rubber (Max. Temp. 180℃)

Epoxy (Max. Temp. 250℃)

Standard diameter for reference:

Diameter (mm): 5, 6, 6.5, 8, 9.5, 10, 12, 12.5, 14, 15, 15.8, 16, 18, 19, 20, 25.4

Diameter (inch):1/4”, 3/8”, 1/2”, 5/8”, 3/4”, 1”

Note: high power heating pipes are used in the mold. The installation hole should be reserved on the mold according to the size of the single head heating pipe (or the outer diameter of the heater should be customized according to the size of the installation hole). Please minimize the gap between the heater and the installation hole. When making the installation hole, gap between the heater hold is recommended within 0.05 mm.

Note: When install high power cartridge heaters in molds, it’s important to minimize the gap between the heater and the installation hole within 0.05 mm.

For more information regarding cartridge heater construction options, please download the [PDF].

Download PDF

Where are cartridge heaters used?

Due to the small size and high heating power of cartridge heater, it is especially suitable for heating metal molds. It is usually used with thermocouples to achieve good heating and temperature control effects.

Main applications of cartridge heater: stamping molds (shaping mold), hot cutters, packaging machinery, injection molds, extrusion molds, rubber molds, melt blown molds, hot press molding machinery, semiconductor processing, pharmaceutical machinery, uniform heating platforms, liquid heating, etc.


In traditional plastic molds or rubber molds, a cartridge heater is inserted inside the mold to ensure that the plastic and rubber materials in the mold runner are always in a molten state.

In the stamping die, the cartridge heater is arranged according to the shape of the die, so that the stamping surface can reach high temperature. It is especially suitable for high-strength plates or thick plates to increase the efficiency of the stamping process.

Cartridge heaters are used in packaging industry and thermal cutting knives. The cartridge heater is embedded in the edge banding mold or the thermal cutting knife mold, so that the entire mold reaches a uniform high temperature, and the material is melted, bonded or melted at the moment of contact. The uniform type cartridge heater is especially suitable.

The cartridge heater is used in the melt-blown mold, installed inside the melt-blown mold to ensure that the interior of the mold, especially the position of the hole, is at a uniform high temperature, so that the material can be ejected through the hole after melting. The uniform type cartridge heater is especially suitable.

Cartridge heaters are also used in the uniform heating platform,multiple heaters are embed horizontally in the metal plate, and adjust the power of each cartridge heater by calculating the power distribution to make the surface of the metal plate reach a uniform temperature. The uniform heating platform is widely used in target heating, precious metal peeling recovery, mold preheating, etc.

What details should be confirmed for custom cartridge heaters?

① Select the sheath material

② Confirm voltage and power

③ Confirm the diameter and heating length

④ Select the installation method

⑤ Select the wiring method

What is the relationship between the voltage, resistance and power?

The formula for voltage (E), resistance (R), power (W), and current (I) is:

W = E²/R = I²*R = E*I

After the product is processed, its resistance value is fixed, so if the input voltage of the product is increased, the power will also increase substantially, and the current will change accordingly. This is the reason why the voltage cannot be increased when operating, it is easy to cause the surface load of the cartridge heater to be too high or the current being too large, which will damage the heater.

What is the surface load of cartridge heater?

The surface load is defined in the machinery industry standard as the power per unit area on the heating surface, in watts per square centimeter (W/cm²). The maximum surface load that each type of sheath materials can withstand is different. When inquiry cartridge heaters with REheatek, it is necessary to communicate with REheatek sales or engineers to get the best solution.

How to calculate the surface load?

Surface load (W/cm²) = power/ (diameter*3.14*length of heating section)

Surface load for different applications:

Heating air (dry heating): the surface load needs to be below 8W/cm².

Heating mold: normally below 12W/cm².

Customized high surface load: can be custom to 18W /cm².

What’s the difference between internal (swaged in) and external (crimped on) wiring construction of cartridge heater?

The difference between external wiring and inner wiring construction can be clearly seen from the above figure.

External wiring construction is that the lead wires are connected with conductor pin by end crimps outside the heater, and internal wiring construction is that the lead wires are connected inside the heater.

The external wiring construction usually uses fiberglass sleeves to prevent the connection part from bending too much, and to increase insulation protection.

For more details about internal and external wiring construction, please check out this article “What’s the difference of Swaged in and Crimped on heaters" on our website.

What are the precautions for using cartridge heaters?

Gas heating

First is to ensure that the installation location is well ventilated, so that the heat generated by the heater can be quickly transferred. Cartridge heater with a high surface load are used in a poorly ventilated environment may increase surface temperature excessively, which may burn out the heater.

Liquid heating

Sheath should be selected based on the type of liquid, especially when liquid is corrosive and corrosion resistant material is required. The surface load of the cartridge heater must be controlled according to the medium of the heating liquid. Here you can refer to the article on our website for better understanding: "How to choose the heater sheath material?” /a>

Mold heating

Reserve a mounting hole on the mold according to the size of the cartridge heater (or customize the outer diameter of the heater according to the size of the mounting hole). Please minimize the gap between the heating tube and the mounting hole within 0.05mm.


The gap between the heater and the mounting hole should not be too large:

When the installation gap is too large, the heater and the mold are not close enough, heat on the heater surface can not be transferred to the metal, which will infect the life time of cartridge heaters.

In addition, the heating time will be prolonged and will slow down the response time of the temperature control.

It is recommended to use reamed holes on the mold to install cartridge heaters. If the temperature of the heating object is below 300℃ and does not require temperature precision, drill holes will do.


Before installation, ensure the hole is clean without oil residue:

Before installing the heater, make sure that its surface is free from foreign matter and oil stains. , Oil residue will be carbonized after heating, which will affect the heat conduction of the heater and may cause damage to the heater.

Note: The heater should be installed firmly when using it

The unfixed cartridge heater is easy to move back and forth in the hole, which may cause the heating area to be exposed to the air or the lead wire to enter the high temperature area and damage the heater, causing electric shock, fire and other accidents. Heaters can be fixed by means of screw or fixing accessory.

Note: Customize the hole depth of the mold according to the length of the heating section of the heater.

If the hole is too shallow, the heating section of the heater will be exposed after installation and without good heat dissipation environment, which will damage the heating tube and may even cause fire and other accidents.

If the hole is too deep, the heater end part and lead wire may be inside the mold after installation. Long-term use in this environment may cause problems such as a short circuit between the electrodes.

Note: Avoid bending of the lead

The bending of the lead can easily cause problems such as breakage and short circuit at the bend part. If the lead wire needs to be bent or bent repeatedly during use, please contact Reheatek  sales or engineers to choose a more suitable construction.

Note: Cartridge heater should be protected from moisture. It is recommended to start with a low voltage at initial use.

Storage and use in a high-humidity environment will decrease the insulation. The insulation performance will gradually recover after the power is turned on. It is recommended to start with a low voltage.

Note: When connecting the leads, make sure that the crimps are firm

When lead wires are connected with conductor pin by crimp not firmly, contact resistance will increase and rising the temperature, which will damage the heater and causing fire and other problems.

Note: It is necessary to control the temperature of the heater wire outlet, flange or fixing ring.

Wire outlet temperature should be controlled below 130°C.

Temperature around flange or a fixing ring heater, temperature around the flange or fixing ring should be controlled below 180°C.

Note: Please use heater within the rated voltage range. Do not operate it at higher voltage.

The resistance of the heater is fixed, a different operating voltage will change the power. Heaters should be used under rated voltage, higher voltage will increase the power, higher temperature may damage the heater, causing fire and other accidents.

Note: Do not make the high-power cartridge heater dry heating in the atmosphere

Even if part of the heating section of the cartridge heater is exposed to the air, lead wire may be broken and causing fire due to abnormal high heating.

Note: Do not mechanically knock or modify the cartridge heater

Knocking or altering the finished cartridge heater may cause problems such as damage to the heater, short circuit, and electric shock.

Note: Do not touch the cartridge heater in operating or just cut off the power supply

It is forbidden to touch the cartridge heater by hand during use, especially the high temperature heaters. Even if you touch it with protective gloves, there is still a risk of burns. When removing the heater, be sure to cut off the power first, and wait for the heater to cool to room temperature .

Suggestion: Use cartridge heater with PID system for temperature control.

The unusually short switching cycle will adversely affect the life of the cartridge heater. In order to ensure the stability of the quality and life time of heater, it is recommended to use a controller controlled by PID.

Product maintenance and replacement

When the heater is repaired, replaced, etc., the power supply must be switched off first to ensure the safety of the operation.

• After power is turned off, wait until the heater has cooled to normal temperature before disassembling, otherwise it may cause burns.

• When there are foreign objects on the surface of the heater, polish it with a dry cloth or fine sandpaper cloth. Do not knock with sharp metal.

• Check whether there is any damage, oil stains, etc. Outside lead wire sleeve. If any abnormality is found, please replace it in time.

• Check whether the lead connection crimps are loose, blackened and oxidized. Replace in time If abnormal.

Special construction cartridge heaters

Built-in thermocouple cartridge heater

Thermocouple (J or K type) could be build inside the heater tip or middle position, grounded or ungrounded to measure the temperature inside the heater. It could be controlled by the controller (such as PID control system).

Uniform cartridge heater

For uniform cartridge heaters, the wire winding density of the two ends is different from the middle. The two ends with higher winding density generate more heat than the middle but with faster heat dissipation than the middle, thus a heating section with uniform temperature is obtained.

Please refer to this article "What’s the Differences Between Reheatek Common Cartridge Heater and Uniform Cartridge Heater?” for more information.

Multiple heating sections cartridge heater

Heating wires with different winding densities are distributed in each section of the heater, so to have multiple heating sections with different temperatures

Extended non-heating/Custom non-heating section

For some specific application requires non heating in some parts of the heater, Reheatek can customize non-heating sections as per requests.

Separately controlled heater

2 or more heating sections in one heater could be controlled separately. Metal plate heating system can widely use this kind heater to control and ensure uniform temperature of the plate by separately control the heating sections of heaters.

Why Choose Our Cartridge Heater

Comprehensive and efficient customization capabilities.

We have professional salesperson who can accurately understand customer needs. We have excellent product engineers with rigorous and solid product design capabilities.

Our experienced production technicians are stable and efficient from product conception, trial production, testing to mass production.

Strict selection of high-quality raw materials

With more than 10 years experiences, we have improved a strict supplier evaluation and review system. We keep cooperating with good quality suppliers, using high quality and most suitable raw materials for customers.

Quality inspection for whole process

Taking product quality as the most basic principle, every process is inspected to ensure product function and quality.

After mass production is completed, the goods will be 100% tested before shipment.

Product test

We have our own product laboratory, which can have various performance tests on the heater products, especially the functional completion and thermal stability during operation.

Technical Parameters

Resistance Heating WireNiCr 80/20 wire
Sheath MaterialStainless steel 304, 321, 316, Incoloy 800, Incoloy 840
Tube DiameterMin is 3mm, max is 30mm
Tube LengthMin is 15mm max is 3m
Maximum Temperature800 degree Celsius
Wattage Tolerance+5%, -10%
Resistance Tolerance+10%, -5%
Voltages Available380V, 240V, 220V, 110V, 36V, 24V or 12V
Length Tolerance± 1 mm
Diameter Tolerance± 0.02 mm
Standard Cold Zone5-10mm
Insulation Resistance (cold)≥ 500 MΩ
Maximum Leakage Current (cold)≤ 0.5 mA

Advantage of Cartridge Heater

Cartridge heaters are small but with quick and precise heating. They are used to heat metal blocks such as dies, molds, and platens by insertion into the drilled holes.

Cartridge heaters are widely used in applications such as packing machines, plastic molding, hot runner molds, laminating presses, automatic welding etc..

In addition, a thermocouple could be integrated into cartridge heater in order to detect temperature and prevent from overheating. Cartridge heaters could be fixed by flange or screws.

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