Key Points to Note for Graphite Rods in Vacuum Furnaces

Graphite rods are frequently used as electric heating elements in high-temperature vacuum furnaces. They help in producing products that oxidize easily at high temperatures, thus making the manufacturing process more efficient. Why are graphite rods so popular in the market? The main reason is their high cost-effectiveness. Graphite rods have excellent thermal and electrical conductivity. For example, their thermal conductivity is higher than that of common metals like iron, lead, and steel, and it decreases with increasing temperature. Their electrical conductivity is four times higher than that of stainless steel and twice that of carbon steel.

Good Uniformity When using a vacuum furnace as an electric heater, it’s crucial to select a heating element with good uniformity in red heat, as this affects the temperature distribution and service life of the furnace. If the red heat uniformity of the graphite rod deteriorates during use, it may lead to rod breakage.

Surface Temperature Due to the nature of graphite rods, higher temperatures shorten their lifespan. If the surface temperature of the graphite rod exceeds a certain level, the oxidation rate will increase, and the lifespan will be reduced. Therefore, it is advisable not to allow the surface temperature to become too high during use.

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Sufficient Voltage Adjustment Margin When heating graphite rods in air, their surface forms an anti-oxidation protective film. To ensure the temperature in the vacuum furnace remains stable, it is beneficial to maintain this film, especially during intermittent use. This stability helps keep the resistance of new graphite rods low at lower voltages.

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Voltage in Later Stages When using multiple graphite rods, the required voltage in the later stages will be higher than the voltage for new rods. It’s important to monitor and adjust the voltage in the later stages according to the voltage regulation method or wiring method. Generally, there will be a certain calculated value for the upper voltage limit in the later stages.