Steel Cutting Blog

In the world of modern manufacturing and metalworking, innovative technologies continue to shape the way we create and fabricate. Among these cutting-edge methods, plasma cutting stands out as a remarkable process, offering precision, speed, and versatility.

Plasma cutting is a high-precision metal cutting process that utilizes a focused jet of ionized gas, known as plasma, to slice through conductive materials. This innovative technology is widely used in various industries, including automotive, aerospace, construction, and metal fabrication, due to its ability to efficiently and accurately cut through a wide range of materials, such as steel, aluminum, copper, and stainless steel.

The process begins with a plasma cutting machine, which includes a power supply and a cutting torch. The power supply generates an electric arc between the torch's electrode and the workpiece, causing the gas (typically compressed air or nitrogen) passing through the torch to turn into plasma. The plasma, with temperatures reaching up to 30,000 degrees Fahrenheit, rapidly melts and blows away the molten metal, creating a clean and precise cut along the desired path.

One of the primary advantages of plasma cutting is its speed and versatility. It can handle both thin and thick materials with ease, allowing for intricate designs and smooth edges. Additionally, the process is capable of piercing through materials, making it ideal for cutting holes or starting points for other machining operations.

Plasma cutting has revolutionized the metalworking industry, offering a faster, more precise, and cost-effective alternative to traditional cutting methods. Its wide range of applications and benefits have made it an indispensable tool in modern manufacturing processes.

In this blog post we will delve into the fascinating world of plasma cutting, unraveling its inner workings and uncovering the myriad of advantages it brings to various industries. Whether you're a student, a hobbyist, or simply curious about the marvels of industrial technology, join us as we embark on a journey to understand this powerful tool that has revolutionized metal cutting and fabrication.

The Basics of Plasma Cutting

First, let’s define plasma.

Plasma is a gas that becomes ionized after being subjected to intense heat, like temperatures above 20,0000C kind of heat. When the plasma is exposed to an electrical or magnetic field it will flow like a liquid.

Today’s applications use a torch, where the plasma cutting machine charges the plasma, squeezes it and forces it through a tiny opening of the torch, creating a hot and high velocity stream. This stream is what will melt through metal, specifically electrically conductive materials like stainless steel, copper, aluminum, and more.

Cost-effective and efficient, plasma cutting is the best option for thick metals, with high cutting precision, perfect for complex shapes.

How Has Plasma Cutting Evolved?

In the early days, the plasma cutting welding process relied on gases like argon and helium. In the 1950s scientists discovered the power of restricting the inert gas flow opening to a nozzle. This helped improve the arc speed and temperature significantly. Now instead of joining or welding metal together it would cut the metal with ease. Then the real experimentation began. Different gas types, flow rates, voltage currents and nozzle size were adapted and tested.

During the 1960s-1970s researchers started using air (oxygen) and water to form as a secondary gas and create a dual flow cutting process. But challenges with nozzle durability, noise level, toxic gases and UV radiation pushed scientists to keep trying new things. By the end of the 1970s companies in Europe were working with underwater plasma cutting to reduce the level of noise, toxic gas and radiation. Underwater cutting came with its own set of challenges though, often plagued by inaccurate cutting and slower speeds.

Enter Thermal Dynamics, an US company that launched the first Low Amp Air Plasma Cutter in the 1980s. Then Hypertherm elevated the technology in 1983 by using pure oxygen, improved on the torch, developed an underwater muffler and sophisticated oxygen injection techniques. These advancements made oxygen plasma and underwater cutting one of the leading plasma cutting technologies in the market still to this day.

In the 1990s the plasma cutting market faced its first real competitor – laser cutting, forcing them to innovate again. New systems with low amps, more precise cuts and higher cutting speeds came out and then plasma cutting took advantage of computer-controlled machines or CNCs. Engineers have even created handheld units for greater versatility.

How Does Plasma Cutting Work?

Using heat, the plasma cutting process melts metal instead of cutting. An electric arc is pushed through a gas (argon, nitrogen, air, oxygen, hydrogen). This gas is passed through a small nozzle, squeezing the gas through at a high speed to form plasma. Cutting the metal involves the cutting tip of the plasma cutter to the workpiece.

There are three main types of cutting process:

1. High-Frequency Contact: Like the name says, this involves using high-frequency part and high voltage. The spark will form when the plasma torch meets the metal, creating the plasma used for cutting.

2. Pilot Arc: In this process, the spark is created inside the torch by combining a low current circuit and high voltage. The spark creates a pilot arc and a small quantity of plasma. When the plasma encounters the metal, a cutting arc is created allowing the operator to start the cutting process.

3. Spring Loaded Plasma Torch Head: Operators press the torch to create a short circuit then the current starts to flow. To start the pilot arc, operators must release the pressure.

What Types of Gas Can Be Used?

One of the advantages of plasma technology is that there are different common gases that can be used, each with its own benefits depending on the material needing to be cut.

Credit Table Source: What Is Plasma Cutting? Working Principle and Its Advantages (rapiddirect.com)

What Types Of Materials Can Be Cut?

As seen in the table above, both aluminum and steel can be cut with a plasma cutting process. However, the range extends far past that. Plasma cutting is ideal for any conductive material:

• Aluminum, an ideal candidate and can be cut up to thicknesses of 160mm.

• Mild Steel is versatile, strong and inexpensive used across all industries.

• Stainless Steel is ideal for plasma cutting since it allows for cutting thickness up to 30 mm.

• Brass is highly conductive making it a great candidate for plasma cutting. It should be processed in a well-ventilated area to avoid inhaling zinc, a component of brass.

• Copper is also highly conductive and great for welding. Similar to brass, cutting it requires good ventilation.

• Cast Iron is inexpensive, malleable and very conductive. It is strong, features a low melting temperature and it makes excellent choice for plasma cutting.

What Are the Advantages of Plasma Cutting?

When it comes to cutting metals, plasma cutting is a cost effective and high production option. But what else does it have to offer?

• High speed: Faster than traditional cutting methods, plasma offers cost effective productivity on the project.

• Higher quality: Plasma cutting produces less slag and residuals on the edge of the metal due to the extreme heat, improving the finished quality of the cut.

• Sharp precision: With the high level of heat involved in plasma cutting, the process achieves higher precision. It also creates a smaller kerf than flame cutting for better processing of unique shapes.

• Ample Versatility: The variety of metals, thicknesses, processes, makes plasma cutting a very versatile option. It works well for groove cutting, planning or marking metals.

• Impressive technology: Plasma cutting has continued to improve over the decades and is compatible with CNC systems for automate processed. The addition of software makes it easier to program a production schedule and include options like automatically loading and unloading parts and finished products. CNC’s increase accuracy and reduce the need for technicians in processing. CNC plasma cutters also allow for fast, safe and high-quality intricate designs in metal.

What Are the Disadvantages of Plasma Cutting?

While plasma cutting offers many advantages to the manufacturing industry, a number of disadvantages cannot be overlooked. Here are a few:

• It only works with conductive materials

• The maximum thickness is 150 mm and does not perform well on plates larger than 1 ½ inches or smaller than ¼ inch

• Proper safety eyewear needs to be worn to protect against bright flashes created during the process

• Operation can be noisy and produce fumes

• The costs can increase due to parts wear down, like nozzles and electrodes

Final Thoughts

Born out of need, plasma cutting technology has continually evolved over the past 80 years to serve the industrial manufacturing industry.

Engineers and scientists alike have invested years of research to fine tune this process, eventually combining it with the CNC technology of the day.

Plasma cutting provides a low-cost alternative for cutting conductive metals. Its ability to work with several gases, and perform under water makes plasma cutting a flexible option.

More efficient and faster than traditional cutting options, plasma cutting can offer a dependable, and high-quality service to any business needing metal cutting.