Cast-In Heaters for Plastics Processing

----Cast In Heaters for Plastics Processing.jpgDurex Industries is a leading edge manufacturer of electric cast-in heater products for the plastics processing industry. Our heaters are utilized as the standard for thermal processing on plastics process equipment throughout the world. Engineering of our electric cast-in products for extrusion applications is based on our years of expertise in the development of these products for the largest equipment manufacturers.

Durex has thousands of standard tooling designs available for immediate use or can custom design a cast heater to fit your application. Our in-house tooling capability can rapidly produce any design available on the market. Cast In heaters for all plastics processing applications including, air and liquid cooled barrel heaters, L-shaped heaters, vent cut out heaters, heat only barrel heaters, air cooled with shroud, and cooling jackets for barrel heaters.

----Liquid Cooled Cast In Barrel Heaters.jpg

Liquid Cooled Barrel Heaters

Liquid cooled barrel heaters are the most common cast -in heater design used on plastics extrusion barrels. The liquid cooling tubes run symmetrical to the heater element, which provides a uniform cooling pattern across the body of the casting.

----Air Cooled Cast In Barrel Heaters.jpg

Air Cooled Barrel Heaters

Finned air-cooled barrel heater designs provide effective heating and cooling for plastics extrusion barrels. The fin pattern can be supplied as a standard height of 1" or manufactured to a low profile thickness for small extruders or applications requiring rapid cooling.

----Air Coold Cast In Heaters with Shrouds.jpg

Air Cooled Heaters with Shrouds

Individual shroud and blower systems can be used with finned barrel heaters as self contained systems on extruder barrels. The shrouds are manufactured as cast aluminum with bolt mounting or a hinged clamshell design fabricated from stainless steel.

----L Shaped Square Cast In Barrel Heater.jpg

L-Shaped Square Barrel Heaters

The "L" shape heater design is typically used on square and rectangular extruder barrels, which utilize a twin, screw design. In most cases, the high operating temperatures in these applications require these cast-in heaters to be constructed of a bronze alloy, however aluminum alloys are used for applications, which...

----Vent Cut Out Cast In Heater.jpg

Vent Cut Out Heater

Special sections of the cast-in extruder barrel such as a vent or feed throat require custom modifications to fit properly. These vent/cutout heaters are designed with element locations that maximize heater performance, but allow for special machined sections that could not be added to a standard barrel design.

----Heat-Only Cast in Heaters.jpg

Heat-Only Cast In Heaters

Although not a common design, heat only cast-in barrel heaters are available primarily with the stainless steel mounting strap option. This design is standard 1" thick and can be used with all standard electrical terminations that Durex offers. The heat only design can be used on piping areas that...

----Cooling Jackets for Cast in Barrel Heaters.jpg

Cooling Jackets for Barrel Heaters

Cast-in cooling jackets are manufactured for specific applications that do not require heat, but require a uniform cooling source, which can be controlled. The cooling jacket typically is 1" thick with 1/2 " cooling tubes that are either stainless steel or Incoloy® depending on the application. As with other liquid cooled...

Heater Specifications & Options

Cast Materials Maximum Operating Temperatures
Aluminum 443 800°F (427°C)
Aluminum 319/356 700°F (371°C)
Bronze / Copper Alloys 1400°F (769°C)
Iron 900°F (482°C)

If required, other cast materials are available.

Cast Processes - Durocast™ perm-mold system uses steel permanent molds. No bake sand system for special castings and short production runs.

Machine Finish - CNC machining is performed for tight tolerances and complex configurations. Milled finishes are provided per specification. Belt sanding, lapping and polishing available to meet application specifications.

Standard Machine Finish Range: 64 to 125 rms.

Fine Finish Per Specifications: 8 to 32 rms.

Standard Flatness: Belt sanded, .015, Milled .005, Lapped, .001

Holes, Cutouts, Thermowells - Mounting or clearance holes, cutouts and thermowells, for inserting temperature measurement probes, cast-in or machined per your specifications.

Inserts - Threaded studs, precision component parts, bushings and special design parts cast acccurately in place.

Electrical - Resistance tolerance NEMA standard +10% -%5

Element Diameter .200 .260 .315 .430 .475
Maximum Voltage 240 240 277 600 600

Three phase available on large heaters. Maximum watt densities depends on size and application. Consult a Durex Engineer.

UL Component Recognition - DA Series cast in heaters are recognized per file E110394.


  • Electrical per UL 499 and UL 1030
  • Canadian Standard C22.2 No.72
  • Dimensional per specifications using Coordinate Measure Machine
  • Quality standard per MIL-Q_9858A


Electrical Data



  • The energy put out by a heating unit is measured in watts.
  • The power factor is always unity.





Cooling Tube Terminationsview images

Type C1 Termination - Plain cooling tube cut to standard 3" length extending from the heater. Specify longer length if required.

Type C2 Termination - 37° Flare nut fitting allows for cooling tube connection to a compression fitting.

Type C3 Termination - Compression fitting mounted directly to cooling tube provides seal for high pressure hook up. Available in standard 3/8 " and 1/2 " NPT. 3/8 " Dia. #55-0010 1/2 " Dia. #55-0011.

Type C4 Termination - Brazed seal with locknut provides an effective seal for high-pressure applications. Mating fittings available upon request.

Type C5 Termination - Brazed angle fitting mounted directly to the cooling tube with right angle 3/8 " FPT as standard. Specify L dimensions.

Type C6 Termination - Cast-in fitting with standard 5/8 " FPT for quick installation of cooling lines with no additional fittings.

Electrical Terminationsview images

Type S Termination - 10-32 threaded screw terminal with a ceramic insulator. Included nuts and washers. Type S standard for cast-in heaters. 6-32, 8-32 and metric sizes also available.

Type A Termination - Right angle terminal block seated on mica washers with 10-32 threaded stud. Included nuts and washers.

Type R Termination - Screw lug terminal seated on mica washers and welded to pin. Includes 8-32 screw for wire connection.

Type D Termination - Quick-disconnect spade lug with 1/4 " blade welded to pin. Other blade sizes available upon request.

Type T Termination - Ceramic insulator with a ceramic top for insulation of electrical connections. Includes complete Type "S" termination with 10-32 threaded stud.

Type HS Termination - Soldered directly to the heating element for moisture-proof termination. 10-32 screw terminal includes nuts and washers. Diameter: .430" - Length: 1 1/8" - Thread: 1/4 - 28, Diameter: .315" - Length: 1 3/8" - Thread: 10 - 32, Diameter: .250" - Length: 1 5/8" - Thread: 8 – 32

Type P Termination - Plain pin for field attachment of termination. Pin length is 1/2 " standard.

Type L Termination - Terminal lug with 10-32 screw is welded directly to the heater pin. Can be oriented straight or at a right angle.

Type C Termination - Flexible armor cable for abrasion resistance with a high temperature lead wire attached to the heating element. Specify L dimension when ordering.


Cast Heater Protective Housingview images

Type B1 Housing - Explosion proof cast iron housing with 1/2 " NPT double hub. Single phase design shown. Larger housing for 3 phase design also available.

Type B2 Housing - Explosion proof cast iron housing with 1/2 " NPT single hub. Single phase design shown. Larger housing for 3 phase design also available.

Type B3 Housing - Standard size stainless steel sheet metal box with two 1/2 " electrical knockouts. Other sizes and types available.

Type B4 Housing - Stainless steel terminal enclosure with male ERGE plug mounted on top. Mating connections available upon request.

Type B5 Housing - Die cast aluminum enclosure with 1/2 " or 3/4 " threaded electrical connections mounted to vented cooling tower. Other sizes and types available for single and 3 phase designs.

Type B6 Housing - Explosion resistant box with 1/2 " NPT single hub, designed for low profile applications. Single phase only. Different hub configurations are available.

Cast In Heater Special Services

  • Radiograph (X-ray): Confirmation of internal element configuration and casting soundness available through x-ray.
  • Plating/Coating: Electroless nickel plating, anodize, teflon® coatings and special blasted surfaces are available per customer specifications.
  • Pressure Testing: High pressure leakage testing is done in-house per application requirements.
  • Heat Treating: Stress relieving and aging through heat treating available as required.
  • CMM Inspection: Coordinate Measuring Machine used for precision quality control of tight tolerance machining requirements.
  • Helium Leak: Detect microleakage from casting body.
  • Temperature Uniformity: Conform heat uniformity across the finished surface.
  • Class 1000 Clean Room: Clean room assembly and packaging per class 1000 standards.
  • Solidworks 3D Modeling: Engineering software provides 3D models of proposed or existing product designs.
  • Custom Packaging: Customer specific packaging for delicate surfaces, large multi-product shipments, or long term storage.
  • Life Cycle Testing: Life cycle test chamber for longterm testing of uniformity and performance characteristics.
  • Material Certification: Precise records and certifications on materials which require traceability to specific standards.
  • Sensor Calibration: NIST traceable calibration lab for calibration and certification of any temperature sensor requirements.
  • FEA Analysis: Preview of proposed design constructions using FEA analysis.

Installation & Maintenance Guidelines for Cast Heaters

  • Always ensure that cast-in heaters are properly mounted to the application to avoid warping of flat heaters or "walking" of barrel heaters. After the initial start-up, retighten the heater mounting system to assure complete surface contact. Periodically check the bolts or straps and tighten as required maintenance.
  • Tighten all liquid cool connections securely to avoid rupture from internal steam pressures. Cast in C6 fittings or brazed connections are the most reliable. Properly maintain these connections to avoid leaks that will destroy the heater. Do not operate heating and cooling simultaneously to avoid thermal shock of the cooling tubes.
  • It is recommended that water used for liquid cooling applications be treated to avoid corrosion and hard water deposits that will clog the cooling tubes over time.
  • Install proper temperature control prior to operation of the heaters to ensure protection from over-temp situations which may damage the heater or equipment. Periodically changing temperature sensors is good preventive maintenance.
  • Electrical terminals must be properly insulated and made tightly to ensure safe operation. All heater installations must be properly grounded. All electrical terminations must be made per applicable Electrical Safety Codes and O.S.H.A. regulations.
  • Do not operate the heaters outside of the voltage and temperature of the design. This will cause the heaters to fail.
  • ALWAYS disconnect the electrical power to heaters prior to service.

Request a quote or contact us for assistance.

Back to Top


  • Vacuum forming
  • Pressure assist forming
  • Drape and press forming
  • Barrel and sprue bushing heating
  • Hopper heating
  • Manifold heating
  • Hot runner systems

Request Info