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The plasma cutter is now used in different industries. Where high precision cutting of metals of different densities is necessary. Plasma is common and useful equipment to heat and melts the material until finished the cut. Plasma is a state of matter. It happens when an ionized and conductive gas is heated at high temperatures. But do you know how does a plasma cutter work or how the cutting process works? Here you can know the details about ‘how does a plasma cutter work’.
What is plasma?
To understand how the plasma cutter works, we must first know what plasma is. Do you know what it is?
In science, we have always learned that there are three states of matter. They are solid, liquid and gaseous. But there is a fourth state: plasma. It sounds confusing, but it’s not. Here’s a simplified explanation below:
The difference between the three states is based on their relative energy levels. Let’s look at the example of ice. When we add heat energy to the ice, it will melt and form water. When we add more energy, the water will evaporate. And become vapor, representing the 3 states of matter.
But if we add a lot more energy to the steam (by heating) the vapor will decompose into various component gases. Becoming electrically conductive or ionized, thus forming what we call plasma. To know more Click here.
How does the plasma cutter work?
The CNC plasma cutter and manual have a similar operation. They use gas to transfer energy from a power source to any conductive material. That will result in a cleaner and faster cutting process than with the flame cutting.
Plasma arc formation begins when a gas, is forced through a small hole in the nozzle inside the torch. The external power supply generates an electric arc. Which introduced into this high-pressure gas flow. This results in what known as a plasma jet.
The plasma jet immediately reaches up to 22,200°C temperatures. That is enough to pierce the workpiece and expel the molten material.
Plasma cutter components
To create the plasma arc, the cutter must have three main components. They are a power supply, the arc starter console, and the plasma torch. You can add other components according to the cutting characteristics they need. And the end-use they will give the equipment.
Power supply. The plasma power supply converts the AC line voltage into a constant and smooth DC voltage. It varies from 200 to 400 VDC. This DC voltage handles maintaining the plasma arc throughout the cut. It regulates the required current output. Which depends on the material type and the thickness it processed.
Arc Start Console: The ARC circuit produces an AC voltage of approximately 5,000 VAC at 2 MHz. That produces the spark within the plasma torch to create the plasma arc.
Plasma torch: Its function is to provide adequate alignment and cooling of consumables. There are three main consumable parts required for plasma arc generation. They are the electrode, the rotating ring, and the nozzle. An extra protective cap you can use to further improve the quality of the cut. And all parts merge together by internal and external retention caps.
Types of plasma cutter systems
The plasma cutting systems refer to some categories. The three most common are:
Conventional plasma cutters: – They usually use compressed air as plasma gas. The nozzle orifice defines the shape of the arc. The approximate amperage of this type of plasma arc is 12 to 20-kilo amperes per square inch. All portable systems use conventional plasma. They are still used in some mechanized applications where parts tolerances are higher.
Precision plasma cutting systems: – Also known as high current density. They are designed to produce the sharpest and highest quality cuts. The torch and consumable designs are more complex. Also, the extra parts are included to constrict and shape the arc. A precision plasma arc is approximately 40 to 50-kilo amperes per square inch. Many gases are used as plasma gas. Such as oxygen, high purity air, nitrogen and a mixture of hydrogen /argon/nitrogen. It is useful for optimal results in a multitude of conductive materials.
Manual operation: – In a common manual plasma system, the parts are side connected to each other. Here the electrodes and the consumable parts of the nozzle interact with each other. Also, the torch closed inside. After pressing the trigger, the power supply produces direct current. That current flows through the connection and starts the flow of plasma gas.
Once the gas builds up enough pressure, the electrode and the nozzle separate. Which causes an electric spark that converts the air into a plasma jet. Then the flow of direct current changes from the electrode to the nozzle. Also, it passes through a path between the electrode and the workpiece. This current and airflow continue until releasing trigger.
Operation of the plasma cutter
Currently, precision plasma cutters are the most chosen by the industry. Thanks to the quality of the cut and its operation that is safe and secure. Also, more efficient with the consumption of energy and plasma gas. In this plasma torch, the electronic parts and nozzles are not separated from each other. It is a common area covered by a separate rotating ring that has small vents. Which turns the pre-flow gas into a whirlpool.
When a start command is issued to the power supply, it generates up to 400 VDC open circuit. And starts the gas through a hose cable attached to the torch. The nozzle is connected to the positive potential of the power supply. A pilot arc circuit helps to connect this line. On the other side, the electrode is negative.
A high-frequency spark is then generated from the arc starter console. It causes the plasma gas to become ionized and conductive. It results in a current path from the electrode to the nozzle creating a plasma pilot arc.
The pilot arc makes contact with the workpiece. At the same time, the current path changes from the electrode to the workpiece. Then the high frequency switched to close and the pilot arc circuit opens.
After that, the power supply increases the cutting current selected by the operator. And replaces the pre-flow gas with the best plasma gas to cut the material. A secondary protection gas that flows out of the nozzle through a protective cap is also used.
Advantages of Plasma Cutting
The plasma cutting process is often quite compared to the oxyfuel cutting process. Because of the characterized by being a metallurgical cutting process. Its main feature is the expulsion of the heated material by the action of oxygen pressure. Thus generating larger amounts of residue.
But despite this comparison, the advantages of plasma cutting over oxyfuel are many. The main advantage is the significant reduction in the risk of deformation. It happens due to thermal propagation in the cutting zone. Also, to its high cutting speed.
But there are also many other reasons that are making the industry choose plasma cutting. Are they:
- Generates more savings over applicable gas;
- Efficient cutting process, as it does not need post-operation;
- Easier operation, providing increased productivity;
- Clean cut without leaving slag, there is no need to use a grinder later;
- It provides cutting a wide range of thicknesses. Also can cut metals with different thicknesses, depending on the equipment used;
- Cuts all types of conductive metal. Such as carbon steel, stainless steel, aluminum, bronze, copper and cast iron;
- Drilling without preheating (which is required in oxyfuel);
- This process is easy to handle and understand. Thus providing very effective and very quick training for the operator.
Care of flame heat and waste
Despite these many advantages, the plasma cutting process is a thermal process. So it generates a lot of heat and leaves solid waste that needs to be better controlled.
For this, a worker should always wear adequate heat and flame protection during working. Face protection is critical and proper shading lenses should be adopted.
The waste generated by the plasma cutter also known as fumes. To reduce the effects of fumes the industry should be careful. They should as far as possible adopt slag removal, exhaustion and cleaning systems produced during plasma cutting. The aspirated cutting tables are great options in this regard.
Want to know more about how does a plasma cutter works? You can ask us.
Our Top 12 Plasma cutters review.
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