Square Cartridge Heaters

Product Sample PhotographsCatalog PDF File

Our advanced swaged, square cartridge heaters combine the utility of a square configuration with the high watt density capabilities of swaged construction. The Duratherm square cartridge offers the reliability and performance required for the most demanding of applications.

Our total commitment to engineering excellence is reflected in our successful efforts to improve heater performance and production efficiency. The results obtained clearly establish “MAXPAK” as the most consistent, reliable and economical cartridge heater on the market.

Quality Design and Construction.

  1. Premium Quality Element Wire. Nickel-chromium resistance wire is precision wound on a high purity ceramic core to optimum computer generated gauge and pitch specifications. Element wires overlap the internal pins and are swaged into a metallurgical bond for optimum connection life.
  2. Superior Element Positioning. Precision centering of the square element assembly insures optimum heat uniformity around the cartridge periphery. The square element configuration positions the element wire in close proximity to the cartridge sheath providing rapid and efficient heat transfer to the application.
  3. Densely Compacted Ceramic Insulation. The magnesium oxide ceramic insulation is compressed to near theoretical density in order to provide the best combination of heat transfer and dielectric strength. This dense mass of compacted ceramic also provides maximum resistance to shock and vibration.
  4. High Temperature Alloy Sheath. Available sheath materials include various stainless steel and incoloy compositions. Additional metal sheath compositions can also be supplied as applications dictate.
  5. Welded End Seal. A square metal end disc of the same alloy as the sheath is heli-arc welded into the end of the cartridge. This seal weld provides the positive seal required for liquid heating applications as well as eliminating the possibility of contaminants entering the disc end of the cartridge.
  6. Durable, Heat Resistant Lead Systems. The standard high temperature leads exit from the cartridge through a protective ceramic end cap. The lead insulation is recessed well into the cap to eliminate any possibility of exposing bare wire when bending the leads sharply at the lead end. Standard leads consist of ten inches of UL approved stranded wire. The lead wire insulation is UL rated for 842°F/450°C continuous operating temperature.


Our extended range of imperial square cartridge cross sectional dimensions was established to provide our customers with a full service source for virtually any square cartridge cross section required. A wide assortment of lead and seal options, construction variations and mounting options ensures compatibility with both new and existing heating applications.

  • Extended Imperial Cross Sectional Dimension Range
  • All Combinations Of Sizes And Ratings Available
  • Many Popular Lead And Seal Options
  • Standard Integral Sensor Styles
  • Wide Range Of Standard Mounting Options
  • Many Standard Construction Options

Special Purpose “MAXPAK”
Square Swaged Cartridges

Duratherm manufactures a variety of special purpose “MAXPAK” square cartridge heaters for many common specialized heating applications. These special purpose cartridges are designed to provide the optimum physical, thermal and electrical characteristics for the precise application for which they were designed.

  • Runnerless Injection Mold Heaters
  • Thermoset Mold Platen Heaters
  • High Performance Heaters
  • High Wattage Immersion Heaters

Custom square cartridge heaters can be manufactured to customer specifications or can be engineered to satisfy the specific requirements of special applications. Custom square cartridges often consist of standard units with relatively minor design modifications but may include a variety of the special features noted below.

  • Unique Application Oriented Lead Configurations
  • Special Non-Standard Cross Sectional Dimensions
  • Extended Temperature And Wattage Performance
  • Corrosion Resistant And Exotic Sheath Materials
  • Low voltage Element Designs
  • Special Multiple Sensor Options
  • Unique Custom Engineered Construction Options
  • Special Purpose Mounting Fittings

Product Sample Photographs

Click on each image to enlarge
"MAXPAK” Square, Swaged Cartridge Heaters In An Assortment Of Lead Styles & Configurations
“MAXPAK” Square, Swaged Cartridge Heaters Featuring Kapton Over MGT Leads & RTV Potted Seal
“MAXPAK” Square, Swaged Cartridge Heaters With Center Lead Exit, Kapton Leads & Epoxy Seal
“MAXPAK” Square, Swaged Cartridge Heaters Section To Show Element Configuration
“MAXPAK” Square, Swaged Cartridge Heaters With Swaged-In Stainless Steel Braid
“MAXPAK” Square, Swaged Cartridge Heaters .375 Square Cross Section With Ground Lead

Catalog PDF File

Click to download PDF file here
Square Cartridge
Introduction and Selection
Square Cartridge Dimensions and Electrical
Dimensional and Electrical Specifications
Square Cartridge Wattage
Wattage Recommendations
Square Cartridge Thermal and Electrical Options
Thermal and Electrical Construction Options
Square Cartridge Mechanical
Mechanical Construction Options
Square Cartridge Mounting
Mounting Options
Square Cartridge Lead
Lead Options