Resistance wire (NiChrome Wire and FeCrAl Wire for example), used as heating material in many industrial production field, whose service life has a significant importance to the normal production. While due to various causes, resistance wire burns out or breaks off during heat generation. According to our customers’ experience, Engineers of NiWire Industries have found the reasons after researching.
1. Analysis of Causes
● Supply voltage is too high
Most resistance wire is exposed in air. Once supply voltage is too high, resistance wire is easily oxidized and breaks off at last at high temperature.
● Different material with joint connection
Resistance wire such as nichrome wire and FeCrAl wire, the expansion efficiency is different from joint connection. When resistance wire is heated up, oxide will increase at the joint which is easily blown.
● The coiling of resistance wire is not even
The higher density is, the higher temperature will be. After a long time, the coil will be broke down.
● Purity of resistance wire
More foreign remains in resistance wire, more oxide will be formed during heating which will cause the break of resistance wire. NiWire Industries use pure nickel plate to produce nichrome alloy, such as Nichrome 80/20.
● External factor
Frequent opening furnace door causes the thermocouple slip off, then actual temperature in furnace is much higher than setting temperature; in the furnace of three-phase four-wire, the voltage will come higher when neutral wire is broke off. Resistance wire will been also broken off if measures not taken.
2. We can take following maintenance measures:
● We can use three-phase voltage regulator to make the voltage invariable in some important heating equipments.
● Clean the oxide on the joints. When cleaning resistance wire with high power, we can firstly immerse the joint in acetic acid for 10 minutes then take off oxide with steel wire brush or cloth. At last make it dry after cleaning again with alcohol. How to connect the joint to wire? Use petrolatum to wrap around the joint with low temperature resistance wire. While we can use glass dust to agglutinate the joint with high temperature resistance wire, soldering is also fine.
● Clean oxide on the resistance wire regularly.
● Check the position of temperature measurers to see if they are loosened.
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