In the late 1990s, as electric heating tubes became widely adopted in China, their designs diversified. In southern China, the type of heating tube used for molds, with electrical leads exiting from one end, was vividly named the "single-end heating tube." Internationally, it is known as a "cartridge heater," also a descriptive term because the cartridge casing is cylindrical and sealed at one end, which conveys a similar idea to the Chinese name "single-end heating tube."
Application Scope of Cartridge Heaters:
Mold heating, which has gained wide acceptance in modern industrial applications.
Heating systems in plastic machinery.
Pharmaceutical production lines.
Laboratory heat treatment experiments.
Chemical industry and related fields.
Advantages of Cartridge Heaters:
Small diameter, achievable from 3-25 mm.
Length is not restricted, achievable from 20-2000 mm.
High power density, achievable up to a surface load of 20 watts/cm², and even up to 60 watts/cm² internationally.
Performance Requirements for Cartridge Heaters:
Heating-up Time: Under the test voltage, the time for the element to heat from ambient temperature to the test temperature should not exceed 15 minutes.
Rated Power Tolerance: Under conditions of sufficient heat dissipation, the deviation of the element's rated power should not exceed the following specified ranges:
For elements with a rated power ≤ 100W: ±10%.
For elements with a rated power > 100W: +5% to -10% or 10W, whichever is greater.
Leakage Current: The cold-state leakage current, as well as the leakage current after hydrostatic pressure and sealing tests, should not exceed 0.5 mA. The hot-state leakage current at operating temperature should not exceed the value calculated by the formula below, with a maximum limit of 5 mA.
I = 1/6 (t × T × 0.00001)
I - Hot-state leakage current (mA)
t - Heating length (mm)
T - Operating temperature (°C)
When multiple elements are connected in series to the power supply, leakage current testing should be conducted on the entire group as a whole.
Insulation Resistance: During factory inspection, the cold-state insulation resistance should be no less than 50 MΩ. After the sealing test, or after long-term storage or use, the insulation resistance should not be less than [specified value] MΩ. The hot-state insulation resistance at operating temperature should be no lower than the value calculated by the formula below, but with a minimum of not less than 1 MΩ.
R = [(10 - 0.015T) / t] × 0.001
R - Hot-state insulation resistance (MΩ)
t - Heating length (mm)
T - Operating temperature (°C)
Dielectric Withstanding Strength: The element should withstand the specified test voltage under the specified test conditions for 1 minute without flashover or breakdown.
Ability to Withstand Switching Cycles: The element should be able to undergo 2000 switching cycle tests under the specified test conditions without damage.
Overload Capacity: The element should withstand 30 cycles of overload testing under the specified test conditions and input power without damage.
Heat Resistance: The element should withstand 1000 cycles of heat resistance testing under the specified test conditions and test voltage without damage.
