Custom Cartridge Heaters UK | Cartridge Heater Manufacturer

Soloheat manufacture bespoke Cartridge Heaters, also commonly referred to as Rod Heaters / Cylindrical Heaters / Insertion Heaters, for a vast range of high-temperature plastics processing and industrial heating applications.

Need a fast quotation? Send us your drawing, survey sheet or existing heater reference for a same-day technical review – click here.

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We stock a growing range of standard cartridge heaters available to purchase online with live pricing.

✔ Standard diameters

✔ Popular wattages

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Soloheat Electric Cartridge Heaters are supplied to OEM machine builders, maintenance contractors and end users worldwide. We manufacture from customer drawings, survey sheets, sketches or existing samples and can advise on the most suitable heater design for both replacement and new-build applications.

Cartridge Heater Features:

High-density cartridge heaters
Low-density cartridge heaters
Swaged cartridge heaters
Mineral insulated cartridge heaters
Metric cartridge heaters
Imperial cartridge heaters
Miniature cartridge heaters
Integrated thermocouple cartridge heaters
Stainless steel cartridge heaters
Incoloy cartridge heaters
Corrosion-resistant heaters
bespoke cartridge heaters
Highest application temperatures available > 700oC / 1292oF

Watt Densities and Maximum Available Lengths:

Low Watt Density Heaters = 5W / cm | 6000mm Long
Medium Watt Density Heaters = 15W / cm |6000mm Long
High Watt Density Heaters = 35W / cm | 2500mm Long

Minimum dimensions available:

6mm / ¼” Dia = Length > 32mm
8mm / 5/16” Dia = Length > 38mm
10mm / 3/8” Dia = Length > 38mm
12mm / ½ ” Dia = Length > 50mm
14mm / 9/16” Dia = Length > 50mm
16mm / 5/8” Dia = Length > 50mm
20mm / ¾” Dia = Length > 75mm
25mm / 1” Dia = Length >100mm

Applications

Soloheat Cartridge Heating Elements are suitable for the heating of Mould Tools, Extrusion Tooling, Press/ Platens, Aerospace and Power Generation components, Packaging Machinery, Heat Sealing Equipment, Food Process Machinery, Catering equipment, Printing, Hot Foil Printing, Laboratory and Test Equipment.

Typically available as Low, Medium or High Watts Density (see our power selection guide below), they are ideal for heating applications as listed below, where external heating space is limited and can be made to incorporate thermocouples, retaining plates / washers, threaded bushes and angled elbows to ensure the best fit.

Mould Heating Elements
Die Heating Elements
Tool Heating Elements
Hot Plate Heaters
Packaging Machine Heaters
Plastic Processing Heaters
Manifold Heaters
Injection moulding
Aerospace
Medical
Pharmaceutical
Food machinery
Rubber processing
Motorsport
Nozzle Heaters (although technically a different product in some cases)

Termination

Cartridge heaters (Rod Heaters) are commonly fitted with power leads (plain fibre glass, steel braided sleeve, ptfe insulated, armoured conduit) Plain Nickel pin and threaded terminals are also common. Further options are available according to client requirements. See below a guide for some of the more common termination types we offer:

How Cartridge heaters work

Our precision Cartridge Heating Elements consist of a nickel-chromium resistance coil embedded within highly compacted magnesium oxide insulation and enclosed in a precision-ground stainless steel sheath. The compacted insulation provides excellent electrical insulation while efficiently transferring heat from the resistance wire to the outer sheath. When installed into a close-tolerance bore, heat is transferred rapidly into the surrounding metal, providing accurate and uniform process heating.

As standard they are manufactured with evenly distributed power. However, we can manufacture heaters with variable internal windings to produce gradual, inactive or variable wattage zones.

Cartridge Heater Power Density

In industrial electric heating, watt density is the amount of power applied to a given surface area of the heating element. It is typically expressed as W/cm², W/in², or watts per linear inch for cartridge heaters. Higher watt density means more heat is generated from a smaller surface area, resulting in faster heat-up but higher element temperatures.

Here’s how the three categories are generally defined:

Low Watt Density

Lower operating sheath temperature.
Minimises scaling and carbonisation.
Ideal where the heated material has poor thermal conductivity or is heat-sensitive.
Typically provides the longest heater life.

Medium Watt Density

The most common choice for industrial applications.
Offers a good compromise between warm-up time and longevity.
Suitable where good heat transfer is available without extreme operating temperatures.

High Watt Density

Produces the greatest heat output from the smallest heater.
Enables very fast warm-up times.
Requires intimate contact between the heater and the heated component to avoid overheating.
Often demands precision-machined holes (for cartridge heaters) and closed-loop temperature control.

Choosing the Right Watt Density (also see below guide)

The correct watt density depends on several factors:

Material being heated – Metals can usually accept higher watt densities than plastics or liquids.
Heat transfer efficiency – Better contact allows higher watt densities.
Required heat-up time – Faster heating generally requires higher watt density.
Maximum operating temperature – Higher temperatures may necessitate higher watt density but also better temperature control.
Expected service life – Lower watt densities generally result in longer heater life.

General Rule

Low watt density = Maximum heater life and gentle heating.
Medium watt density = Best all-round industrial solution.
High watt density = Fastest heating and highest power output, but only where excellent heat transfer and temperature control are available.

*Please note that these ranges are guidelines rather than fixed standards. The optimum watt density should always be selected based on the application, operating temperature, material properties, and installation conditions rather than a single numerical value.

Bore hole guidance

For optimum performance, cartridge heaters should be installed in precision-machined bores with the correct clearance. Excessive clearance creates air gaps that reduce heat transfer, resulting in higher sheath temperatures and shorter heater life.

A suitable heat transfer paste may be used as a quick fix for air gaps, although re-boring and fitting a slightly larger heater is the best option if possible. We can also centreless grind heaters to ensure a more precise fit should re-boring not be viable.

Cartridge Heater Installation Guide

Correct installation is essential to maximise heater performance, efficiency and service life.

Ensure the bore is clean and accurately machined. A close fit between the heater and the bore is critical for efficient heat transfer. Remove all dirt, oil and debris before installation.
Use the correct bore size. An oversized hole reduces heat transfer and can cause the heater to overheat prematurely.
Insert carefully. Push the heater fully into position without excessive force. Never hammer directly onto the electrical leads.
Support the leads. Ensure the lead wires are protected from abrasion, sharp edges and excessive movement. Use strain relief where necessary.
Avoid overheating the lead exit. Keep the lead end of the heater outside the heated zone wherever possible (ensure it’s not inserted beyond the end of the heater tube).
Use temperature control. Fit within a suitable thermostat or temperature controlled loop to prevent overheating and extend heater life.
Allow for removal. Where practical, incorporate a means of extracting the heater for future maintenance or replacement. Extraction is sometimes long, hard & hot work without pre-planned extraction points etc.

Safety Notes

Disconnect the electrical supply before installation or maintenance.
Verify that the supply voltage matches the heater rating.
Ensure all electrical connections comply with local electrical regulations.
Do not operate a cartridge heater in free air unless it has been specifically designed for that purpose.
Inspect the heater for damage before installation and replace any damaged units.

Following these guidelines will help achieve optimum heat transfer, reliable operation and maximum service life from your cartridge heaters.

Cartridge heater Lead times

We have a standard range of Cartridge Heaters available to purchase from our on-line store – see bottom of this page.

Typical lead time for Cartridge heaters is 7 – 10 days. Premium express services are available as below:

48 Hour despatch service: cost + 100% premium
5 – 7 day despatch service: cost +50% premium.
We confirm manufacturing lead times at the time of quotation.

To order or enquire

Click here to download our Cartridge Heater survey sheet template

Alternatively, e-mail us as much of the following info as possible:

Diameter
Length
Wattage
Voltage
Termination type (include Lead Length & protection type where applicable)
Retaining tab / threaded fixing bush / location flange (include sizes) where applicable
Integrated Thermocouple required (If yes, grounded or insulated tip?)
Application of heater
Qty of heaters required
Delivery time required

Cartridge heater warranty

Please refer to section 6 of our Terms and Conditions of Business regarding warranty.

Why choose Soloheat Cartridge Heaters?

With over 45 years of experience manufacturing industrial heating elements (Est. 1980), Soloheat supplies custom Cartridge Heaters to OEM machine builders, maintenance contractors and end users throughout the UK and worldwide. Every heater is manufactured to customer specification, whether from a drawing, survey sheet or existing sample. Contact us now.

FAQ's - Cartridge Heater Elements

How tight should a cartridge heater fit?

For efficient heat transfer, a cartridge heater should be installed in a precision-machined bore with a close sliding fit. Excessive clearance creates an insulating air gap, causing the heater sheath to operate at a higher temperature, reducing efficiency and potentially shortening service life.

Can you manufacture cartridge heaters to customer drawings or samples?

Yes. We regularly manufacture bespoke cartridge heaters from customer drawings, sketches, survey sheets or existing samples.

What watt density should I choose?

Selecting the correct watt density depends on the material being heated, operating temperature, available heat transfer and the speed at which heat is required:

Low watt density is suitable for temperature-sensitive materials or applications with limited heat dissipation.
Medium watt density is ideal for most general industrial heating applications.
High watt density provides rapid heat-up times where excellent heat transfer is available, such as precision tooling and metal moulds. (see also our guide on this page)

How long do cartridge heaters typically last?

The service life of a cartridge heater depends on several factors, including watt density, operating temperature, installation quality and the application itself. When correctly specified and installed in a close-tolerance bore, high-quality mineral insulated cartridge heaters can provide many years of reliable service.

Can cartridge heaters be supplied with an integrated thermocouple?

Yes. We can manufacture cartridge heaters with various type integral thermocouples to provide accurate temperature monitoring close to the heating element.

What sheath materials are available?

Most cartridge heaters are manufactured with high-quality stainless steel sheaths, offering excellent corrosion resistance and durability for general industrial applications. Where higher operating temperatures or more demanding environments are involved, alternative sheath materials can be specified. Our engineers will recommend the most suitable construction based on your operating conditions and application.

What voltages can cartridge heaters be manufactured in?

Custom cartridge heaters can be manufactured to suit a wide range of supply voltages, including 12V, 24V, 48V, 110V, 120V, 230V, 240V, 415V and other customer-specified voltages. We also manufacture heaters with custom wattages to achieve the required heat output for your application.

Can I replace a cartridge heater with a higher wattage?

Not always. Increasing the wattage without considering the application can raise the sheath temperature beyond its safe operating limit, leading to premature heater failure. Any increase in wattage should be assessed alongside the bore fit, material being heated and required operating temperature. We can recommend a suitable replacement that improves performance without compromising reliability.

More questions? Click here here to ask our engineers.