This is a high-performance, industrial-grade tubular heating element. Its core features are external lead wires and "Class A" insulation grade, making it suitable for applications with extremely high demands for safety and reliability.

1. Material

· Metal Sheath:

· Common Materials: Stainless steel (SSU304, SUS321), Titanium alloy (Ti), high-temperature resistant Incoloy (e.g., Incoloy 800/840), etc.

· Selection Basis: Chosen based on the operating environment (e.g., temperature, corrosive media). Incoloy offers excellent performance in high-temperature oxidation and carburization resistance.

· Insulating Filler: High-purity, dense modified Magnesium Oxide (MgO) powder. It provides excellent electrical insulation and thermal conductivity while maintaining stability at high temperatures.

· Resistance Wire: High-temperature Iron-Chromium-Aluminum alloy (FeCrAl) or Nickel-Chromium alloy (NiCr). FeCrAl is suitable for higher operating temperatures, offers good oxidation resistance, and has a long service life.

· Terminal Assembly:

· Structure: This is the core difference from "internally wired" types. It uses ceramic terminal posts (or mica sheets) and metal bolts to form a terminal chamber at the end of the heater.

· Lead Wires: Users need to connect external high-temperature wires (e.g., silicone rubber wire, ceramic fiber wire) to these bolts.

· Advantages: The connection point is isolated from the high-temperature zone of the tube, resulting in a more robust connection, replaceable wires, and easier maintenance.

2. Dimensions

· Highly Flexible: The dimensions of externally wired heaters are not standardized and are fully customized according to the customer's heating requirements and installation space.

· Tube Diameter (D): Common range from Φ6mm to Φ30mm or larger.

· Heating Length (L): Ranges from tens of millimeters to several meters.

· Shape: Can be manufactured not only as straight rods but also bent into U-shape, W-shape, annular (ring), or various other complex shapes.

· Terminal Chamber Size: Designed with sufficient space according to power and voltage ratings to ensure safe electrical clearance.

3. Voltage & Power

· Rated Voltage: Extremely wide range, from tens of volts (e.g., 48V, 110V) to hundreds of volts (e.g., 220V, 380V) or even higher. The most common are 220V and 380V, for direct connection to industrial power grids.

· Rated Power: Ranges from hundreds of watts to tens of kilowatts, depending on the design based on size, voltage, and surface load.

· Key Design Parameter - Surface Load: This is the core of Class A heater design. It is strictly controlled within a safe range that ensures long service life, based on operating temperature and heating medium (air, water, metal mold). The ratio of power (W) to the surface area of the heating zone (cm²) must be appropriate.

4. Characteristics

· Class A Insulation Grade (Core Feature):

· Refers to meeting high standards for electric strength (withstand voltage) under normal conditions. It typically means passing a high-potential test of 2000V AC / 50Hz, applied for 1 minute, without breakdown or flashover.

· This ensures extremely high electrical safety and reliability even in harsh industrial environments.

· High Terminal Reliability: The external wiring method solves the weakness of internally wired types, where leads are prone to damage at the root due to high temperature and vibration. The connection is more robust, leading to a longer lifespan.

· High Power & High Temperature: Utilizes high-performance materials and rigorous design, enabling it to withstand higher surface temperatures and power densities.

· Excellent Mechanical & Chemical Properties: A variety of sheath material options provide resistance to corrosion, oxidation, and physical impact.

· Long Lifespan & Stability: Precise manufacturing processes (e.g., compaction density of the filler) and optimized surface load design ensure thousands or even tens of thousands of hours of service life.

· Requires Temperature Control System: Given its high power, it must be used with a closed-loop control system including thermocouples, temperature controllers, and contactors to prevent dry-firing and overheating.

5. Applications

Class A externally wired heating tubes are used in various demanding industrial heating fields with harsh environments.

· Industrial Plastic Machinery: Heating for injection molding machines, extruder barrels, and hot runner systems.

· Chemical Equipment: Heating and insulation for reactors, storage tanks, and pipelines.

· Packaging & Food Machinery: Heat sealing jaws, drying ovens, sterilizers.

· Home Appliance Industry: High-end instant water heaters, electric ovens, coffee machines.

· Industrial Furnaces & Ovens: Used as heating elements providing heat source for air, liquids, etc.

· Semiconductor Equipment: Wafer baking, heating stations in etching equipment.