Cartridge Heaters - German Engineered

Cartridge Heaters for Industrial Applications

Cartridge heaters are a very effective source of high-density heat transfer where surface heating isn’t adequate to maintain desired temperatures.  PTC cartridge heaters allow for compact design, and no additional control circuitry is required to maintain temperature.

The cylindrical form of the PTC ceramic disk embedded in silicone with aluminum or stainless outer housing provides highly effective heat transfer and durability.  The cylindrical shape allows the heater component to fit tightly into drilled and reamed holes in molds for plastic extrusions, medical devices, engine blocks, or vessel housing walls.

There is a wide variety of applications for these specialized heaters.

• Plastic Molding

• Hot Stamping

• Medical Equipment

• Laminating

• Extrusions

• Food Processing

• Catering

PSA series of PTC cartridge heaters

These compact cartridge heaters come in diameters as small as 6mm or 0.236 inches and lengths of 48mm or 1.89 inches for medical devices or 3D printing heads.  Surface temperatures can be selected from 176 to 428 degrees Fahrenheit in this smallest size. The voltage can be 110-240 Volt with little difference in watt density.

The largest in this series is 22mm in diameter and 60 mm in length.  Pressing at the tend of the cartridges is available to support proper insertion depth.

* Power measured in ice-water (~ 0°C / 32°F) at 230V 

** Available without pressing (Order No: xxx.01) or with pressing (Order No: xxx.02) to increase strain relief (>30N)

ESA series of PTC cartridge heaters

If your application will expose a cartridge heater to harsh chemicals or just need more robust construction the ESA series of heaters have a stainless steel jacket, screw, and nut fastener or cable gland as required.  

Various sizes are available off the shelf.  10 - 11 mm diameter and 55 - 75 mm in length for 12-24 V and 110 - 240 Volts.  Surface temperatures range from 185 degrees F to 428 degrees F

* Power measured in ice water (~ 0°C / 32°F) 

** Available without cable fitting (Order No: xxx.01) or glanded (O.No: xxx.02; see drawing) 

*** IP68 Test Conditions: Heater immersed in a 2m column of water for 48 Hrs 

Six things you need to know when selecting cartridge heaters.

How much total wattage will you need?

The total wattage required is based on the available voltage, the type of solid or liquid to be heated, and the overall dimensions.  The surface heat of the PTC cartridge heater radiates in a cylindrical fashion rather than a point source at the end of the heater.  

One device may be adequate for the head of a 3D printer, but larger dies may need multiple cartridge heaters to distribute the heat throughout the die evenly.

The rated surface temperature of the PTC cartridge heaters is based on free air T 77 degrees F without airflow.  The heat transferred to the solid material or liquid will be determined by the heat transfer characteristics of that material.

The cartridge should be used in a drilled or reamed hole a few mm larger than the device diameter to improve heat transfer.  A silicone-based grease is usually applied to the outside of the cartridge to enhance heat transfer and prevent seizing the cartridge to the size of the solid material for future removal.

When heating liquid materials inside a vessel or along a transfer tube, multiple heaters may also be used to maintain the temperature required.  If in doubt about what you need for your application, it is best to speak with an experienced thermal management engineer familiar with these devices.

This power calculator for enclosures might be helpful.

Where will the heaters be positioned?

Positioning is based on what material is being heated and where the heat is concentrated or kept even throughout the material.  For solid materials, the holes should not be any longer than the length of the cartridge heater.  If the holes are more profound, care must ensure the wire termination remains outside of the hole opening.  

The wire terminations are rated to withstand the heat produced at the termination with the device but not inside the heated material.

When heating liquid material inside a container, positioning the cartridges is important.

The location should be lower on the container to maintain the circulation of the heat by convection.  

What are the heat transfer characteristics of the materials?

All materials have specific heat transfer characteristics, and their mass determines the heat that remains within the materials.  The heat transfer rate is determined by the combination of materials the heat must travel through to reach the material to be heated.  Read more about the heat transfer characteristics of PTC heaters.

Air is a good insulator of heat transfer, so the surface of the cartridge must be in close contact with the exterior interior of the drill hole where it is inserted.  Coating the interior of the hole or the exterior of the cartridge heater with heat transfers gel helps prevent air gaps that impede heat transfer.

Why do PTC cartridge heaters have a higher watt density?

PTC resistive elements are small ceramic disks that, for their size, have a high watt density compared to resistive wire.  The ceramic elements are very durable, requiring no maintenance.  For better performance, the elements are embedded in silicone rubber with an outer shield of aluminum.  Read how PTC heaters work.

Are temperature controls necessary with PTC heaters?

Positive temperature coefficient or PTC identifies the electrical resistance to the current flow of these devices as the temperature increases. Initially, the resistance to current is meager, allowing the maximum amount of current to flow and heat the device quickly.  

As the temperature increase, the resistance increases logarithmically, slowing the current flow and automatically maintaining the temperature.  There is no need for additional temperature sensors or controls to manage the temperature in most applications.  When used in tiny spaces, this makes them ideal heaters with little room for other controlling devices.

There is a maximum inrush current for each device that requires slow blow type fusing rated for this inrush current.  Read the practical guide to electronic enclosure design.  When temperature controllers are necessary this line of DIN rail mounted controllers can be used.

Where can I get expert help in selecting a cartridge heater?

DBK USA has thermal management experts to answer all your questions and help identify the right cartridge heater for your application.  Custom sizes and outputs are available if needed.