Air Carbon Arc Cutting & Gouging (AAC) Basics
AAC electrode types, air jet function, power source requirements, polarity settings, safety PPE, and defect prevention.
- Identify the correct AAC electrode type for mild steel
- Explain the purpose of the air jet in the AAC process
- Describe power source requirements and duty cycle considerations for AAC
- Explain how to increase or decrease gouging depth
- State the required PPE and safety practices for AAC operations
Lección 1
AAC Electrodes & Process Fundamentals
What is Air Carbon Arc Cutting?
Air Carbon Arc Cutting (AAC) - also called arc-air gouging - is a thermal process that uses an electric arc between a carbon electrode and the workpiece to melt metal, while a high-pressure air jet blows the molten material away. AAC is primarily used for gouging, back gouging, and removing defective weld metal rather than through-cutting.
AAC Electrode for Mild Steel
The air carbon arc cutting electrode most commonly used for mild steel is a DC copper-coated electrode. The copper coating serves a critical function that we will cover in a later module, but the key exam fact is that copper-coated DC electrodes are the standard choice for mild steel applications.
The Purpose of the Air Jet
The purpose of the air jet in the AAC process is to blow molten metal away. The compressed air stream follows directly behind the arc, ejecting the molten metal from the groove as it is created. Without adequate air pressure, the molten metal would resolidify in the groove, creating defects.
Carbon Deposits and Weld Quality
Carbon deposits left in the groove cut by the AAC process result in brittle welds. When carbon from the electrode contaminates the groove surface and is not properly removed before welding, the carbon dissolves into the weld metal. This excess carbon increases hardness and reduces ductility, producing a weld that is prone to cracking under stress.
Critical - Carbon Contamination
Always grind the groove after AAC gouging to remove carbon deposits before welding. Carbon contamination causes brittle welds that are prone to cracking.
When to Turn On the Air
When using the AAC process, the air is turned on before the arc is established. The air must be flowing before you strike the arc so that molten metal is immediately blown away from the first moment of gouging. Striking the arc without air flow would allow molten metal to pool and resolidify in the groove.
The standard AAC electrode for mild steel is DC copper-coated. The air jet blows molten metal away. Air must be turned on before the arc. Carbon deposits in the groove cause brittle welds.