Gouging with a Plasma Cutter | Expert Guide

Gouging is a technique in which a plasma cutter is used to remove, melt, or groove a part of metal from the original workpiece. Surely, sharp and smooth gouging can only be achieved with the best plasma cutters having at least 40 AMP capacity.

This article will discuss the technical and qualitative aspects of plasma arc gouging as well as suggest a few suitable plasma cutters for the best quality gouging results.

Why do metal workers perform gouging?

Fabricators and metalworkers use gouging for several reasons that are listed below:

• Material Removal: Gouging is operated to remove excess material from the edge or surface of the workpiece, such as weld buildup, defective welds, or unwanted metal. It’s a more controlled, quick, and precise method compared to traditional methods like grinding or chipping.
• Preparation for Welding: Gouging can be used to prepare a workpiece for welding by creating a groove or bevel in the material, ensuring better weld penetration and adhesion. This is so useful if the welding is to restabilize any rusted or broken part of the original metal.
• Cutting and Shaping: Gouging is also used to cut or shape metal, especially in situations where a precise and controlled cut is necessary. It’s often used to create specific profiles or grooves in metal pieces. For instance, installing a metal pipe becomes easy if you groove and make a small hole in the thick metal which further helps protect the pipe in the future.

• Surface Cleaning: Plasma gouging can be used to clean and prepare the surface of a metal piece by removing contaminants, rust, or old coatings.
• Weld Joint Preparation: In applications where groove or bevel joints are required for welding, gouging helps create the necessary groove profile to achieve strong and quality welds.
• Repair Work: Gouging is valuable for repairing or modifying metal structures, as it allows for the removal of damaged or unwanted sections, followed by welding in new pieces.
• Non-Destructive Testing (NDT): Gouging can be used to create test samples or specimens for non-destructive testing to assess the integrity and quality of welds or materials.

Overall, gouging with a plasma cutter is a versatile process that offers precision and control in material removal and preparation, making it a valuable technique in various metalworking and fabrication applications.

Best Plasma cutters for gouging

Below are the top three plasma cutters we recommend to perform plasma gouging

1. Hypotherm Powermax 45 XP (Best of all)
2. Miller Electric plasma cutter
3. Hobart Airforce 40i

Hypotherm Powermax 45 xp

When it comes to plasma gouging, the Hypertherm Powermax 45 XP stands as the pinnacle of performance and versatility. In fact, this is one of the best-sold plasma cutters with built-in air compressor. This exceptional plasma cutter offers a recommended cut capacity of up to 16 mm (5/8″), impressive cut speeds, and automatic gas adjustment for hassle-free setup and operation. Let’s delve into why the Hypertherm Powermax 45 XP is the best choice for plasma gouging, along with its pros and cons.

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Why Choose Hypertherm Powermax 45 XP for Plasma Gouging:

Versatile Applications: The Powermax45 XP is a true workhorse, supporting a wide range of applications. Whether you need to drag cut across the workpiece, perform extended reach cutting in confined spaces, gouge precisely, or mark part identification, this plasma cutter has you covered. It excels in tasks like spot weld removal and fine feature cutting with minimal dross and heat affected zones.

Ease of Use and Smart Technology: This plasma cutter is designed with user convenience in mind. Even first-time operators will find it easy to use, thanks to patented drag-cutting technology. Smart Sense™ technology ensures that air pressure is always correctly set, eliminating guesswork and reducing setup time. The torch disable switch feature makes consumable changeouts faster and more efficient.

Outstanding Productivity: Experience increased productivity with cut speeds 1.5 times greater than oxyfuel on 6 mm (1/4″) mild steel. The superior cut and gouge quality reduce the need for post-processing, such as grinding and edge preparation. This plasma cutter gets the job done efficiently, saving you time and effort.

Rugged and Reliable: Duramax® Lock torches are built to withstand high-impact and heat, ensuring durability and longevity. The SpringStart™ technology guarantees consistent starting and optimum torch performance. With Hypertherm Certified™ reliability, you can trust this machine to perform flawlessly, even in demanding environments.

Environmentally Friendly: The Powermax45 XP is environmentally conscious, boasting plasma cutting efficiency that’s 11% better than its predecessor. It consumes less power while cutting more steel in less time. Additionally, all plasma system components are recyclable, contributing to a greener footprint.

Gouging works done by Hypotherm powermax 45 xp:

Pros

• Versatile applications, from cutting to precision gouging and marking.
• User-friendly operation with patented drag-cutting technology.
• Smart Sense™ technology ensures accurate air pressure settings.
• Improved productivity with rapid cut speeds.
• Rugged and durable Duramax® Lock torches.
• Environmentally friendly, with better cutting efficiency and recyclable components.

Cons

• Limited automation options (not suitable for CNC).
• Gouging capabilities are restricted to specific consumables.
• Single-phase power support; not compatible with 3-phase.
• Lack of a remote trigger.

What is the difference between plasma cutting and gouging?

Plasma cutting and plasma gouging are both processes that use a plasma arc to work on metal, but they serve different purposes and involve distinct techniques. Here’s a breakdown of the differences between the two, with examples for better understanding:

Operating difference

Plasma cutting is primarily used to cut through metal to create clean and precise edges. In a nutshell, the primary objective of plasma cutting is to separate the workpiece from the original. It may be done to convert the original workpiece into two or more pieces along a defined cutting path.

On the other side, plasma gouging is used to remove material from a workpiece, typically to create grooves, and cavities, or to clean and prepare surfaces. It’s a controlled material removal process.

Difference in Technique

During plasma cutting, the plasma arc is focused on the workpiece, and a high-velocity stream of ionized gas (plasma) is directed at the metal. The intense heat generated by the plasma arc melts the metal, while a high-velocity gas stream blows away the molten material to create a clean cut.

Imagine you need to cut a sheet of stainless steel into smaller pieces for a fabrication project. You would use plasma cutting to make precise and straight cuts along your desired measurements.

Alternatively, in plasma gouging, the plasma arc is directed at the metal surface with an inclined direction and has a defocused arc, but instead of cutting through the material entirely, it removes a controlled amount of material by melting and blowing it away. This process is often used to prepare weld joints, remove defective welds, or create grooves for various purposes.

Let’s say you have a welded joint that needs to be repaired. You can use plasma gouging to remove the defective weld material, leaving a clean groove behind. This prepares the joint for a new weld, ensuring a strong and quality bond.

What is the recommended Plasma gas for Gouging?

The recommended plasma gas for gouging typically depends on the material you are working with and the specific gouging application. Here are some commonly used gases for plasma gouging and examples of when to use them:

Compressed air

Air is suitable for gouging a wide range of materials, including carbon steel, stainless steel, aluminum, and more. Compressed air is commonly used for general-purpose gouging, such as preparing weld joints, removing old welds, or cleaning surfaces. It’s versatile and readily available, making it a popular choice.

Nitrogen

Nitrogen is preferred for applications where surface cleanliness is crucial, such as in the food or pharmaceutical industries. It produces minimal oxidation and contamination compared to air. It is also used to gouge stainless steel.

The amount of nitrogen used for gouging stainless steel can vary depending on several factors, including the specific gouging equipment, the thickness of the stainless steel, and the desired gouging quality. However, as a general guideline, the flow rate of nitrogen for gouging stainless steel typically ranges from 15 to 35 cubic feet per hour (CFH).

Oxygen

Oxygen is suitable for applications where you want a faster gouging process. It creates a chemically reactive plasma that accelerates material removal. However, it can lead to increased oxidation on the gouged surface.

Typically, plasma gouging can be performed with either air or oxygen as the plasma gas. Here’s a general guideline:

• Air Plasma Gouging:

Air plasma gouging uses compressed air as the plasma gas, which contains approximately 21% oxygen. The air-to-gas ratio is typically set at 1:1 (equal parts of air and gas).

• Oxygen Plasma Gouging:

Oxygen plasma gouging uses pure oxygen as the plasma gas. The oxygen-to-gas ratio is 100% oxygen, meaning there is no other gas mixed in.

If too much oxidation occurs during plasma gouging, it can lead to several issues such as Oxidation can increase the rate of material removal, making it challenging to achieve precise gouging and generate more heat, potentially increasing the size of the heat-affected zone in the base metal.

Argon-Hydrogen Mixtures

Argon-hydrogen mixtures are used for gouging non-ferrous metals like aluminum and copper. This mixture is ideal for applications where you need precise control over the gouging process and minimal heat-affected zones. It’s often used in the aerospace industry for gouging aluminum components.

There are also Some specialty gases, such as argon-helium mixtures or specific gas blends, may be used for highly specialized gouging applications, such as in the nuclear industry. These gases are chosen based on specific requirements, such as minimizing contamination, achieving precise control, or meeting strict industry standards.

Steps for plasma gouging

Plasma gouging is a process used to remove excess material or prepare surfaces for welding. Here are the steps to perform plasma gouging effectively:

1. Choose the Right Plasma Cutter with Gouging Capacity:

Ensure that your plasma cutter has the gouging feature. Not all plasma cutters are capable of gouging, so select a machine designed for this purpose.

2. Change Gouging Tip (Replace the Cutting Nozzle):

Swap out the cutting nozzle with a gouging nozzle or tip. The gouging nozzle is specially designed for the gouging process and differs from the cutting nozzle in terms of its shape and the way it directs the plasma arc. It allows for a wider and more controlled arc, suitable for gouging. Check out the plasma-cutting nozzle chart here.

3. Attach the Gouging Cap:

Place the gouging cap onto the torch head. The gouging cap is distinct from cutting caps and is designed to shape and control the plasma arc during gouging. It helps achieve the desired gouging width and depth.

4. Set the Correct Amperage (Amps):

Adjust the amperage setting on your plasma cutter based on the material type and thickness you’re gouging. Higher amperage is typically needed for thicker materials. Refer to your plasma cutter’s manual or guidelines for recommended settings.

5. Follow Safety Practices:

Safety is paramount when performing plasma gouging:

• • Wear appropriate personal protective equipment (PPE), including safety glasses, welding gloves, a welding helmet with the appropriate shade for plasma gouging, and flame-resistant clothing.
  • Ensure good ventilation in your workspace to dissipate fumes and gases generated during gouging.
  • Keep the work area clear of flammable materials and ensure proper fire safety measures.
  • Secure the workpiece to prevent movement during gouging.
  • Maintain a safe distance from the plasma arc and wear a welding face shield or safety goggles with side shields to protect against sparks and UV radiation.

Regarding Electrode Replacement:

Electrode replacement is necessary when the electrode becomes worn or damaged. Signs that indicate the need for replacement include:

• • Irregular or unstable arc during gouging.
  • Reduced gouging performance or quality.
  • Electrode tip deformation or damage.
  • Difficulty in maintaining the set amperage.

Regularly inspect the electrode, and if you notice any of these signs or excessive wear, replace it before gouging to ensure optimal performance and safety.

Remember that plasma gouging can be a versatile and effective process for various applications, such as weld preparation, surface removal, or material shaping. Adhering to proper techniques and safety measures will help you achieve the best results while minimizing risks. Always consult your plasma cutter’s user manual and follow manufacturer recommendations.

Post-cleanup after plasma gouging

After completing the plasma gouging process, there are essential steps and tricks to ensure a clean and safe workspace. Proper post-cleanup is crucial for maintaining equipment and minimizing hazards:

Allow the Workpiece to Cool:

Before handling the gouged area or the workpiece, allow it to cool down. Gouging generates heat, and touching hot metal can result in burns.

Remove Slag and Debris:

Use a chipping hammer, wire brush, or a slag removal tool to remove the slag and debris left behind after gouging. Pay attention to the edges and corners, as these areas often have more buildup.

Inspect the Gouged Area:

Examine the gouged area for any remaining defects, uneven surfaces, or residues. Ensure that the desired depth and shape have been achieved.

Check for Any Embedded Material:

Sometimes, during gouging, small pieces of metal or slag can become embedded in the workpiece. Carefully inspect and remove any foreign material using pliers or a suitable tool.

Grind and Smooth the Surface:

If a smooth surface is required, use a grinder with an appropriate abrasive wheel to even out any rough edges or imperfections. This step is essential for weld preparation.

Clean the Workspace:

Remove all tools, equipment, and debris from the workspace. Ensure the area is clean and clutter-free to prevent accidents and hazards during subsequent work.

Dispose of Waste Safely:

Collect the slag, debris, and any waste materials in a designated container for disposal. Properly label and store hazardous waste if applicable, following local regulations.

Maintain and Inspect Equipment:

After each use, inspect the plasma cutter, torch, and related equipment. Ensure they are in good working condition, and replace any worn or damaged components promptly.

Plasma gouging vs. Arc gouging

Plasma gouging and arc gouging are both metal removal processes used in welding and metal fabrication, but they have distinct differences in terms of how they operate and the applications they are best suited for. Here are the key differences between plasma gouging and arc gouging:

Process

Plasma gouging uses a focused and high-velocity jet of ionized gas, typically compressed air, to melt and remove metal from the workpiece. The plasma arc is extremely hot and concentrated, which results in precise and controlled material removal.

Alternatively, Arc gouging, also known as carbon arc gouging, relies on an electric arc generated between a carbon/graphite electrode and the workpiece. The intense heat of the arc melts the metal, and a continuous air jet blows away the molten material, leaving a gouged groove.

Temperature and control

Plasma gouging operates at higher temperatures compared to arc gouging. The plasma arc is more focused and provides better control over the gouging process, resulting in cleaner and more precise cuts. It can be used for both thin and thick materials.

On the other side, Arc gouging produces a broader and less focused heat source, which can make it less precise compared to plasma gouging. It is often used for thicker materials and is effective for removing large volumes of metal quickly.

Cutting speed

Plasma gouging generally offers faster cutting speeds due to the concentrated and high-temperature plasma arc. It’s ideal for applications that require both precision and speed. On the other hand, the Arc gouging can be slower than plasma gouging because it relies on a wider arc and may require multiple passes to achieve the desired depth or width of the gouge.

Materials and applications

Plasma gouging is versatile and suitable for a wide range of materials, including stainless steel, carbon steel, aluminum, and non-ferrous metals. It is commonly used in industries where precision and clean cuts are essential, such as aerospace and automotive.

Whereas, Arc gouging is often used for heavy-duty applications involving thick steel and cast iron. It is commonly employed in construction, shipbuilding, and maintenance and repair work where speed and efficiency are prioritized over precision.

Equipment and consumables

Plasma gouging requires specialized equipment, including a plasma cutter with gouging capability and specific consumables like gouging nozzles and electrodes.

Arc gouging typically involves a welding machine with carbon or graphite electrodes. It is a more straightforward process in terms of equipment and consumables.