Product Description;
Origin of the Finned Single Head Heating Rod:
The finned single head heating rod is made by filling a metal tube with high-resistance electric heating alloy wire as the heating material. It is filled and compacted around the heating wire, has good insulation performance, and uses high-purity magnesium oxide with high thermal conductivity as the filler. It features high power, high thermal efficiency, and fast heat dissipation, and can be used for plastic packaging, small mold heating, analytical instruments, and the cooling effect during gas expansion.
Selection Principles of Finned Single Head Heating Rod:
Temperature and corrosion resistance: For low-temperature tubes, BUNDY, aluminum, or copper tubes are generally used; for high-temperature tubes, stainless steel or Incoloy tubes are generally used. In cases of severe water quality,
Teflon heating tubes or stainless steel with coating treatment can be used. Stainless steel heating tubes with coating treatment can be used under poor water quality conditions. Incoloy 840 heating tubes have good oxidation resistance at high working temperatures and good corrosion resistance. Generally, domestic 2520 material is used as a substitute for Incoloy code tubes, achieving the same effect.
Performance Indicators of Finned Single Head Heating Rod:
1 Heating time: Under test voltage, the time for the component to rise from ambient temperature to test temperature should not exceed 15 minutes;
2 Rated power deviation: Under full heating conditions, the deviation of the rated power of the component should not exceed the following ranges: for components with rated power ≤100W: ±10%. For components with rated power >100W: +5% to -10% or 10W, whichever is greater;
3 Insulation resistance: At factory inspection, the cold insulation resistance should not be less than 50MΩ;
Usage Precautions for Finned Single Head Heating Rod:
1. During use, high watt-density single head heating tubes heat up quickly but have poor heat dissipation conditions, often causing the outer stainless steel tube to become blackened, oxidized, or deformed. This can cause the internal heating element—the electric heating alloy wire—to melt due to high-temperature dry burning, shortening the life of the single head heating tube. Therefore, a good single head heating tube not only requires good production quality but also requires the mold material and machining hole diameter (the closer the hole diameter to the tube diameter, the better). A suitable hole diameter not only facilitates replacement of the single head heating tube but also helps heat transfer between the two, thereby extending the service life of the heating tube.
2. Deep hole machining of the mold should pay attention to precision; do not drill from both ends, as the junction cannot be tightly sealed and will have larger gaps, causing poor heat dissipation of the heating tube and uneven temperature of the heated body.
3. Pay attention to the magnesium oxide powder at the lead-out end of the heating tube; it should not be exposed to pollutants or moisture in the usage environment to prevent leakage. It is best to leave 5mm outside the mold.
4. When starting up the heating tube, it is best to preheat for 5 minutes to avoid leakage due to air humidity or moisture ingress into the tube. The heating machinery must be equipped with a ground wire.
Selection of Magnesium Oxide Powder for Heating Tubes:
Magnesium oxide powder is located between the resistance wire and the tube wall, providing insulation between them. At the same time, magnesium oxide powder has good thermal conductivity. However, it is highly hygroscopic, so it must undergo moisture-proof treatment (modification of magnesium oxide powder or sealing of the heating tube ends) before use.
Service Life of Heating Tubes
The service life of a heating tube is related not only to the quality of the resistance wire but also to the quality of the magnesium oxide powder and the selection of the resistance wire diameter. For high-temperature heating tubes, KAWAI can manufacture heating tubes with a surface load below 8W/cm². When selecting the resistance wire diameter, the surface load of the resistance wire must be calculated to meet the life requirements.
Environmental Conditions for Heating Tubes:
a. Altitude not exceeding 1000m
b. Ambient temperature -20~50°C
c. Relative humidity of surrounding air not greater than 90% (at ambient temperature of 25°C)
d. No conductive dust, explosive gases, or corrosive gases that can seriously damage metals and insulating materials in the surroundings
e. No significant impact or vibration
Cracking of Heating Tubes:
(1) Poor weld quality of the stainless steel tube, resulting in very low tensile strength;
(2) For new tubes, the drying process is not done properly, causing moisture in the magnesium oxide to rapidly expand under heat and exert high pressure on the tube wall.
(3) Prolonged non-use in high humidity conditions, allowing significant moisture ingress into the tube.
The Most Intuitive Method to Verify the Quality of Electric Heating TubesElectric Heating Tube:
First, wipe the surface of the heating tube clean, then connect it to an AC 220V power supply and dry-burn it in air until the surface turns red. Then disconnect the power and allow the heating tube to cool completely. Wipe it with a napkin; if there is no black oxide powder (indicating no reaction with oxygen in the air) on the white paper, the heating tube is of high quality.
Electric Heating Tube Design
