Cathode fall

Physical-Chemical Mechanism of Action

The cathode is the negative pole in an electric field. Here, electrons are generated by thermal or chemical processes that detach them from the metal crystal and release them. These released electrons form the arc that fills the weld pool.

Metallurgical Relevance & Welding Risks

A too low cathode fall can cause insufficient electron release, impairing arc efficiency and slowing melting. This increases welding time and can lead to incomplete fusion or porosity.

Workshop Practice & Action Guidelines

Ensure the cathode fall is between 10% and 20% of total voltage drop. Monitor arc voltage and adjust current or gas flow as needed to ensure optimal cathode fall.