Vacuum Feedthroughs, Heating Elements, and Custom Process Heaters for Aerospace, University Research, Semiconductor, Medical and OEM Applications

Cartridge Heaters

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Cartridge heaters provide localized heat to restricted work areas requiring close thermal control. Dies, platens and a variety of other types of processing equipment are efficiently heated. Closely controlled work temperatures up to 1400° F (760° C) are obtained by a combination of heater location and proper wattage output.

Belilove Company offers a wide range of cartridge heating units for a variety of applications.

The size, sheath, leads, terminals, wattage and voltage can be adapted to your heating requirements. We offer many low to medium and high watt density cartridge heaters from stock.

We love customs too! Belilove can provide you with heating units manufactured to your specifications to accommodate your application. For these, please fill out the form below.

Backer Hotwatt

Sunrod Split Sheath Miniature Cartridge Heaters

Small footprint, high heat
1/8 inch and 4MM diameters
3 - 240 volt operation
Hundreds of sizes In stock
Heaters as short as 1/2"

Sunrod split sheath cartridge heaters have a novel, innovative design that removes the failure points of conventional miniature heaters. The design includes a continuous resistor packed in maximum density insulation and welded to the heater connections. Lead wires exit through the insulation with a temperature rating of 500 degrees Fahrenheit. Insulation with a temperature rating of 900 degrees Fahrenheit is also available.

SunRod Sunrod Split Sheath Cartridge Heaters
SunRod Operating Illustration

In contrast to typical cartridge heaters, which have cold areas throughout their length and unheated sections at each end, Sunrods generate heat continuously for the whole length of the heater. The even heat dispersion of Sunrod ensures more uniform temperatures for your process.

Sunrods have a unique hot tip that allows you to reach any part of your operation that requires heat.

When activated, the split sheath design of SunRod forces its opposing legs to extend into contact with the surrounding bore for optimal heat transfer resulting in reduced operating temperature and an extended operating - by up to five times!

SunRod elements contract when de-energized, breaking contact with the bore and allowing slide-out removal. SunRods are never going to seize!

You may now apply heat whenever you want! Drill a small bore to the area that requires heating and insert a hot tip SunRod.

Swaged vs. Standard Cartridge Heater Design and Heater Life

Cartridge heaters provide localized heat to restricted work areas requiring close thermal control. Dies, platens and a variety of other types of processing equipment are efficiently heated. Closely controlled work temperatures up to 1400° F (760° C) are obtained by a combination of heater location and proper wattage output.

Heater Life

Cartridge heater life is determined by how efficiently the heat generated in the resistance wire can be conducted away from the wire and into the part being heated.  The efficiency of heat transfer is generally controlled by three factors:

  • Resistance wire watt density
  • Density of insulating material around the wire
  • Fit of the heater into the heated part

There are two basic designs of cartridge heaters - swaged and standard. Although both type heaters look identical, the internal construction is very different.

Standard Cartridge Heater Design

Nichrome wire heating coils are inserted in holes formed in ceramic tubes. Pure magnesium oxide filler is vibrated into the holes housing the heating coils to allow maximum heat transfer to the stainless steel sheath. The heater then has a Heliarc welded end cap inserted on the bottom of the heater and insulated leads are installed. The MGO powder is not compacted and heat transfer is a function of the grain-to-grain thermal conductivity to the heater sheath, and then into the heated part. Because of this, the heater wire watt densities must be kept in the low to medium range.

Standard Cartridge Heater Standard Cartridge Heater

Swaged Cartridge Heater Design

Swaged cartridge heaters wind Nichrome wire around a precision ceramic core and the carefully position the resistance wire and ceramic core uniformly inside the the heater sheath. Pure magnesium oxide (MgO) powder is then vibrated in and the heater is swaged to a specific diameter. Swaging is a process that mechanically forces the heater through a confining die to reduce its diameter and thus compact the powdered MgO to rock-like consistency for greater thermal conductivity. This compressed MGO transfers the heat from the resistance wire much more efficiently. The improved heat transfer allows for higher wire watt densities allowing swaged cartridge heaters to operate at higher temperatures.

Swaged Cartridge Heater Swaged Cartridge Heater

Cartridge Heater Fit

The most common cause of cartridge heater failure is an improper fit in the hole into which it is inserted. If the heater is surrounded by air, an excellent thermal insulator, it cannot dissipate it's heat into the part with optimum efficiency. The result is much higher temperatures on the Nichrome wire and failure.  The goal to longer life with cartridge heaters is to accommodate the tightest fit practical for a given application.

In summary, if you want the longest life cartridge heater, choose a swaged heater and make sure you provide a machined, close tolerance fit between the outside diameter of the heater and the inside diameter of the hole.

Miniature Cartridge Heaters

Roughly defined as electrical cartridge heaters 3" or shorter in length, having diameters of 1/8", 5/32", or 3/16", and providing high watt densities (although low to medium watt densities are available). Their exterior construction is usually 304 or 316 stainless steel, with internal nickel chromium (Nichrome) resistance wire. A variety of electrical lead wire configurations to meet the needs of the application are available. Because of their swaged (machine compressed) construction, miniature cartridge heaters provide a high level of shock and vibration resistance, as well as good dielectric strength.??Miniature cartridge heaters are used to provide localized, concentrated heat to small component parts or in restricted work spaces. Dies and platens, as well as a variety of other types of OEM processing machinery, are efficiently heated by miniature cartridge heaters.

Typical OEM Uses for Miniature Cartridge Heaters

  • Gas monitoring equipment / analyzers
  • 3D printing machine
  • Medical equipment and devices
  • Ink printing and labeling machines
  • Mass spectrometers
  • Analytical process instrumentation
  • Optical equipment
  • Gas chromatography

Operating temperatures as high as 1200 deg. F can be attained with careful attention paid to the application. Miniature cartridge heaters are almost always mounted in a close tolerance holes or swiftly circulating fluids because their often very high power densities would cause them to self-destruct if run full power in open air or stagnant fluids. As with all cartridge heaters, lifespan is directly proportional to the success or ability to move the heat from the internal nickel chromium resistance wire into the heated part or process. Therefore, careful consideration must be giving to hole tolerances or process flow rate before application.  It is common for miniature cartridge heaters to include internal thermocouples for temperature control and limiting purposes.

BCE Engineering & Quality Assurance

BCE engineers provide decades of experience in design and development, delivering a wealth of empirical data and experience. BCE welcomes your custom requirement and will design and deliver a part that meets your challenging needs.

BCE is recognized for its commitment to quality and excellence by being certified in accordance with ISO 9001:2015.
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