Every time an arc is struck the electrode receives a high current surge that brings it from a cold state to an extremely hot state very quickly. The ionized plasma gas flowing past the electrode is full of charged particles . These particles pull away atoms from the hot surface of the electrode which wears away the emitting element and creates a pit in the surface.
The number of starts and stops is more important than actual cutting time in establishing the life of the electrode. It is important to keep an eye on your consumables to know how to evaluate when they need changing. To tell if an electrode is spent, check the pit in the electrode element (the element is the silver-colored insert held in the copper: hafnium for air and O2, tungsten for N2 or Ar-H2). Generally, the pit should not exceed 2.5mm for air and O2 and 3.2mm for N2 or Ar-H2. Electrodes should be changed in time to prevent possibly serious damage to the torch if the electrode bursts inside.

Every time an arc is struck the electrode receives a high current surge that brings it from a cold state to an extremely hot state very quickly. The ionized plasma gas flowing past the electrode is full of charged particles . These particles pull away atoms from the hot surface of the electrode which wears away the emitting element and creates a pit in the surface.
The number of starts and stops is more important than actual cutting time in establishing the life of the electrode. It is important to keep an eye on your consumables to know how to evaluate when they need changing. To tell if an electrode is spent, check the pit in the electrode element (the element is the silver-colored insert held in the copper: hafnium for air and O2, tungsten for N2 or Ar-H2). Generally, the pit should not exceed 2.5mm for air and O2 and 3.2mm for N2 or Ar-H2. Electrodes should be changed in time to prevent possibly serious damage to the torch if the electrode bursts inside.