Why is the quality of MgO so important in heating tube production?
For electric heating tube manufacturers, magnesium powder (magnesium oxide powder, MgO) is the "heart" of the electric heating tube. Its quality directly determines the safety, performance, and service life of the heating tube.
What is Magnesium powder?
The correct name for "magnesium oxide powder" is MgO, an ionic compound composed of magnesium and oxygen. It is a white, odorless, and tasteless fine powder.
In most industrial applications, such as electric heating elements, what we refer to as "magnesium powder" is actually "magnesium oxide powder" (MgO), a stable, non-flammable ceramic material, fundamentally different from flammable metallic magnesium powder.
Why is it crucial to use high-quality magnesium oxide powder in heating elements?
This stems from its four core properties, which directly determine the performance, safety, and lifespan of heating elements:
1. Excellent Insulation
Magnesium oxide is an excellent insulator with an extremely high resistivity (>10¹³ Ω·cm at room temperature). It reliably isolates the energized heating wire (resistance wire) from the surrounding metal casing, preventing leakage or short circuits and ensuring user safety. This is its most fundamental function.
2. Excellent Thermal Conductivity
Magnesium oxide's thermal conductivity (approximately 30-40 W/(m·K)) is far superior to that of air. It efficiently and evenly transfers the high-temperature heat generated by the heating wire to the metal casing, and then to the heated object. This not only improves heating efficiency but also prevents heat accumulation in the heating wire, which can lead to localized overheating and burnout, thereby extending its lifespan. 3. High Chemical Stability and High-Temperature Resistance
3.Sintered magnesium oxide has a melting point of up to 2800°C.
It is extremely stable at the typical operating temperatures of heating elements (several hundred to thousands of degrees Celsius). It does not decompose, volatilize, or chemically react with the encapsulated heating wire or metal tube shell, ensuring long-term reliability.
4. High Mechanical Strength and Packing Density
During the manufacturing process of heating elements, a "tube shrinking" process occurs, where the metal tube is compressed under tremendous pressure to compact the magnesium oxide powder inside. High-quality magnesium oxide powder with a precise particle size distribution can withstand this pressure without crumbling. After compaction, it achieves an extremely high packing density, eliminating internal voids, ensuring maximum insulation and thermal conductivity, and preventing performance degradation due to vibration.
Based on these properties, magnesium oxide powder is primarily used in:
Heating elements: This is the largest application area. It is used in various tubular heating elements (heating tubes), strip heaters, plate heaters, and other applications. It is commonly found in electric kettles, ovens, space heaters, industrial boilers, and more.
In the market, the standard/mid-range grade magnesium powder contains approximately 98% to 99.3% MgO purity, boasting excellent insulation and thermal conductivity, and well-controlled moisture absorption. It meets the requirements of most general-purpose electric heating elements, making it a popular choice for mainstream household appliances such as electric kettles, ovens, microwave ovens, rice cookers, and water heaters.
Common Mesh and Micrometer (μm) Conversion Table:
|
Mesh |
Aperture (μm) |
Description of Application in Magnesium Oxide Powder |
|
20 - 40 mesh |
850 - 425 μm |
Coarse particles are used to form the main framework and provide support. |
|
40 - 100 mesh |
425 - 150 μm |
Medium particles are the main component of the powder body. |
|
100 - 325 mesh |
150 - 45 μm |
Fine particles are used to fill gaps between medium particles. |
|
-325 mesh |
< 45 μm |
Ultra-fine powder, used to fill tiny gaps extremely thoroughly, but too much can affect flowability. |
How should MgO be selected based on heating tube diameter and heating wire?
When selecting magnesium powder, please specify the material, application, diameter, and length of the heating element.
A.For heating tubular with a diameter of 8mm or greater, use 40-325 mesh magnesium powder for medium- and low-temperature applications, such as in rice cooker heating elements.
For heating tubular with a diameter of 7-8mm, use 50-325 mesh magnesium powder for medium- and high-temperature applications, such as in irons and kettles.
For heating tubular with a diameter of 6.5mm or less, use 60-325 mesh magnesium powder for high-temperature applications, such as in ovens and air fryers.
What does the Davinci Machine do for you?
Davinci has specialized in small appliances, including heating element manufacturing, for 15 years. We provide not only equipment and molds, but also raw materials. For startups, we offer one-stop procurement services, helping customers select the most suitable production line and achieve quality products faster, saving them the hassle of inexperienced manufacturing.
Foshan Davinci Technology Co., Ltd
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