A heating element converts electricity into heat through the process of resistive heating. As electric current passes through the element, it encounters resistance resulting in the heating of the element. This process is independent of the direction of current flow.
A typical heating element generally consists of either a coil, a ribbon (straight or corrugated), or a strip of wire that gives off heat, similar to that of a lamp filament. When an electrical current flows through it, the element glows red-hot and converts the electrical energy into heat, which radiates in all directions.
Heating elements are typically either nickel- or iron-based. The nickel-based elements are usually nichrome, an alloy that consists of about 80 percent nickel and 20 percent chromium. Other compositions of nichrome are available, but the 80–20 mix is the most common. It is the most popular material for heating elements because:
- Nichrome has a high melting point (about 1400°C or 2550°F)
- Nichrome does not oxidize (even at high temperatures)
- Nichrome only expands minimally when exposed to heat
- Nichrome has a reasonable resistance to heat, only increasing by about 10 percent between room temperature and its maximum operating temperature.
Nichrome can be used bare or embedded in a ceramic material. Ceramic insulation can make the nichrome more robust and durable, as ceramic can withstand high temperatures and endure periods of heating and cooling.
The size and shape of a heating element is determined by the dimensions of the appliance it fits inside and the area where it produces heat. Hair curling irons have short, coiled elements because they need to produce heat over a thin tube around which hair can be wrapped. Electric radiators have long bar elements that enable the heating of an entire room. Electric stoves have coiled heating elements custom-sized to heat cooking pots and pans.
In the designing of heating elements, electrical engineers must consider multiple performance factors. There are approximately 20-30 factors that affect the performance of a typical heating element, including: the voltage and current, the length and diameter of the element, the type of material, and the operating temperature. Additional factors vary depending on the type of element used. For example, when using a coiled element made of round wire, the diameter of the wire and the form of the coils (diameter, length, pitch, stretch, etc.) are among the things that critically affect the performance. When using a ribbon element, the ribbon thickness, width, surface area, and weight all have to be factored into its design.
Oakley Industrial Machinery Inc. has been a worldwide, leading expert in the heating element & cartridge heating industry with more than 75 years of knowledge and experience in the field. We continue to be at the forefront of innovation, designing and manufacturing of heating element production machinery & terminal pins.
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