What Gas Do You Use with a Plasma Cutter?

Choosing the right gas for your plasma cutter is crucial for achieving optimal cutting performance, cut quality, and cost-effectiveness. We will also address the necessity of air compressors for plasma cutting machines.

The Role of Gas in Plasma Cutting

The gas used in a plasma cutter serves several critical functions:

• Plasma Formation: It's the medium that becomes ionized to create the plasma arc.
• Heat Transfer: It carries heat from the arc to the workpiece, melting the metal.
• Material Removal: It blows away the molten metal, creating a clean cut.
• Cooling: It helps to cool the torch and consumables, extending their lifespan.

Types of Gases Used in Plasma Cutting

There are several different gases that can be used in plasma cutting, each with its own unique properties and applications. The most common gases are:

• Compressed Air: This is the most widely used gas due to its availability and low cost.
• Nitrogen (N2): This is a good all-around gas that provides excellent cut quality on a variety of materials.
• Oxygen (O2): This gas offers the fastest cutting speeds on mild steel but can cause oxidation.
• Argon (Ar): This is primarily used for cutting non-ferrous metals like aluminum and stainless steel.
• Hydrogen (H2) Mixtures (e.g., Argon/Hydrogen): These mixtures provide the highest cutting speeds and the best cut quality on stainless steel and aluminum but are more expensive.

Gas Selection Chart: Matching Gas to Material

Compressed Air: The Economical and Versatile Choice

• Pros:
  • Low Cost: Air is readily available and free, making it the most economical option.
  • Convenience: No need to purchase or store specialized gases.
  • Versatility: Suitable for cutting a variety of materials, including mild steel, stainless steel, and aluminum.
• Cons:
  • Lower Cut Quality: Air typically produces a rougher cut edge compared to other gases.
  • Slower Cutting Speeds: Air cutting speeds are generally slower than oxygen or hydrogen mixtures.
  • Potential for Oxidation: Air contains oxygen, which can cause oxidation on the cut edge of some materials.
  • Moisture Contamination: Air can contain moisture, which can damage the plasma cutter's components and reduce consumable life.
     

Nitrogen: A Good All-Around Performer

• Pros:
  • Good Cut Quality: Nitrogen provides a cleaner cut edge than air.
  • Versatility: Suitable for cutting a variety of materials.
  • Relatively Low Cost: Nitrogen is less expensive than argon or hydrogen mixtures.
• Cons:
  • Slower Cutting Speeds: Nitrogen cutting speeds are generally slower than oxygen or hydrogen mixtures.
  • Requires Gas Cylinder: Requires the purchase and storage of nitrogen gas cylinders.

Oxygen: Speed for Mild Steel, with Caveats

• Pros:
  • Fast Cutting Speeds: Oxygen provides the fastest cutting speeds on mild steel.
• Cons:
  • Limited Material Compatibility: Primarily used for mild steel.
  • High Oxidation: Oxygen causes significant oxidation on the cut edge, requiring post-processing.
  • Fire Hazard: Oxygen is a highly reactive gas and poses a fire hazard. Requires careful handling.

Argon and Hydrogen Mixtures: Premium Performance, Premium Price

• Pros:
  • Excellent Cut Quality: Provides the cleanest cut edge and the narrowest kerf.
  • Fast Cutting Speeds: Offers the fastest cutting speeds on stainless steel and aluminum.
  • Minimal Oxidation: Reduces oxidation on the cut edge.
• Cons:
  • High Cost: Argon and hydrogen mixtures are the most expensive gases.
  • Requires Specialized Equipment: Requires specialized gas mixing and handling equipment.
  • Hydrogen Safety: Hydrogen is a flammable gas and requires careful handling.

Cost Comparison: A Rough Estimate

Is an Air Compressor Necessary for Every Plasma Cutter?

Yes, almost every plasma cutter requires a source of compressed air. There are very few exceptions, such as some specialized underwater plasma cutting systems that might use a different fluid or gas source.

• Internal Air Compressor: Some smaller, portable plasma cutters have a built-in air compressor. These are convenient but typically have limited capacity and may not be suitable for extended or heavy-duty cutting.
• External Air Compressor: Most plasma cutters require an external air compressor to supply the necessary volume and pressure of compressed air.

Choosing the Right Air Compressor: Key Considerations

If you need to purchase an air compressor for your plasma cutter, consider the following factors:

• CFM (Cubic Feet per Minute): The air compressor must be able to deliver sufficient CFM at the required pressure (typically 70-80 PSI) for your plasma cutter. Refer to your plasma cutter's manual for the CFM requirements.
• Tank Size: A larger tank will provide a more consistent air supply and reduce the frequency of the compressor cycling on and off.
• Duty Cycle: The duty cycle indicates the percentage of time the compressor can run continuously without overheating. Choose a compressor with a duty cycle that meets your cutting needs.
• Two-Stage vs. Single-Stage: Two-stage compressors are more efficient and can deliver higher pressures than single-stage compressors.
• Oil-Lubricated vs. Oil-Free: Oil-lubricated compressors are generally more durable and quieter, but they require more maintenance. Oil-free compressors are less maintenance-intensive but can be louder.