POLARIDAD DIRECTA E INVERSA EN SOLDADURA

Understanding Direct and Inverse Polarity in Electrical Current

Real vs. Conventional Current Flow

• The real flow of electric current, or electron flow, occurs from the negative terminal to the positive terminal, known as the actual direction of current.

• The conventional direction of current was established for ease of circuit analysis, flowing from positive to negative despite being contrary to the actual flow.

Characteristics of Direct and Inverse Polarity

• In welding machines with rectifiers, one terminal is always designated as positive and the other as negative; this designation does not change.

• AC machines can switch polarity based on frequency (50 or 60 Hz), while high-frequency AC machines may switch at rates exceeding 20,000 Hz.

Effects on Welding Processes

• Connecting an electrode to the negative terminal results in direct polarity where electrons flow directly towards it; connecting to the positive terminal results in inverse polarity where electrons flow from the base material against the electrode.

• Direct polarity is characterized by a higher concentration of heat in workpieces leading to faster melting but less control over fusion pools.

Applications and Recommendations

• Direct polarity is suitable for short welds on thin materials but not recommended for long weld beads due to increased deformation risks.

• In contrast, inverse polarity concentrates more heat in the electrode allowing for slower melting and better control over fusion pools.

Choosing Electrode Types

• Most electrodes are designed for use with inverse polarity; however, some like E6013 can be used with both polarities.

• It’s crucial to consult specific electrode specifications since characteristics may vary between manufacturers due to technological advancements.