How to choose and use electric furnace wires and resistance strip lead out rods for electric heating tubes?

How to choose and use electric furnace wires and resistance strip lead out rods for electric heating tubes?

Electric furnace wires and resistance strips are commonly used as high-temperature heating elements in various high-temperature experiments and industrial electric furnaces. Due to the high temperature during the operation of the electric heating wire, it is recommended to lead the electric furnace wire and resistance strip out of the furnace through structures such as lead out rods, whether from the perspective of insulation and sealing of the electric furnace or high-temperature protection of the lead out wire.

The lead out rod is made of high-temperature resistant alloy material that is straightened into a straight strip shape, and is slotted or perforated on one side for welding with the electric furnace wire, while the other side is threaded for wiring according to actual needs.

Common lead out rod materials:

Stainless steel material (SUS304, SUS316L, SUS310S and other materials): suitable for medium to high temperatures, with a bright appearance and low resistivity. It is a high-temperature nickel chromium alloy with good oxidation resistance and high-temperature strength;

Iron chromium aluminum material (materials such as 0Cr25AL5 and 0Cr21AL6Nb): high cost performance, high temperature resistance, and high temperature oxidation resistance;

Nickel chromium materials (such as Cr20Ni35, Cr15Ni60, and Cr20Ni80): high oxidation resistance and creep resistance;

Swedish imported materials (KANTHAL AF and KANTHAL D): have higher antioxidant and high-temperature resistance than domestically produced ones;

Imported materials from Japan (such as SUS304, SUS316L, and SUS310S): They have better oxidation resistance and high temperature resistance than domestic stainless steel materials.

Precautions for using lead out rods:

1. Select the appropriate material according to the actual temperature: if the furnace temperature is below 1000 ℃, it is recommended to use nickel chromium alloy lead rods. If the furnace temperature is above 1000 ℃, it is recommended to use iron chromium alloy lead rods.

2. Suitable diameter and length:

1) Select a suitable diameter lead out rod according to the cross-section of the electric furnace wire or resistance strip: Generally, it is recommended that the diameter of the lead out rod be greater than 3 times the diameter of the furnace wire. Common resistance rod diameters: φ 8mm φ 10mm φ 12mm φ 14mm φ 16mm φ 18mm φ 20mm, etc.

2) The lead out rod is not used for heating purposes, mainly for wiring purposes. Therefore, it is necessary to choose an appropriate length according to actual needs to prevent heat transfer from causing overheating of the lead part.

3. Welding between electric furnace wire and lead out rod: It is generally recommended to drill holes and mill grooves on the lead out rod, with the electric heating wire centered through the holes and firmly welded in the groove to avoid sparks and burns caused by unstable welding parts.

4. Connection between the lead out rod and the furnace body: The connection between the lead out rod and the furnace body must be sealed, firm, and insulated. The lead out rod should be placed in the middle of the insulation filler, and insulated and sealed with the furnace body using insulators and sealing fillers.

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