When it comes to industrial tools, there is one powerful device that stands out – the plasma cutter. But what exactly is plasma? And how does a plasma cutter work? In this article, we will explore the answers to these questions and provide you with the best way to comprehend the inner workings of a plasma cutter.
On Earth, plasma is known as the fourth state of matter, following solid, liquid, and gas. Matter transitions from one state to another when it receives enough energy, such as heat. For instance, if you heat an ice cube (solid), it will transform into water (liquid), and if you continue to heat the water, it will become steam (gas). But what happens when you further heat the gas?
As the gas gets heated to a certain degree, it becomes highly ionized and electrically conductive, resulting in the formation of plasma.
Evolution of Plasma Cutters
Plasma cutters are essential in various industries, from locksmiths and auto repair shops to construction enterprises. These tools have undergone advancements in design and capabilities alongside technological progress. Generally, there are two types of plasma cutters and torches: machine-based and handheld.
Handheld cutters, known for their portability and versatility, make welding tasks easier. While they may struggle with thicker metals, they excel in cutting lightweight materials.
On the other hand, large-scale projects require automated plasma cutters that are used in combination with cutting tables and offer additional functionalities. However, these systems are not easily movable, as they require a substantial power source to operate. The choice between a mechanical or manual cutter depends on factors such as the size, shape, and thickness of the material to be cut.
Exploring the Oxy-Fuel Torch
In addition to plasma cutters, oxy-fuel cutting machines are also utilized in manufacturing and machining for cutting challenging materials like steel. These machines heat steel to its ignition temperature using an oxygen/fuel gas flame. The metal is then subjected to a powerful oxygen stream, leading to a chemical reaction that produces iron oxide, commonly referred to as slag. The subsequent elimination of the slag is accomplished through a jet.
Though oxy-fuel torches are not as commonly used as handheld cutting torches, they are still preferred for specific applications. One advantage is their high portability since they don’t require electricity or compressed air to function. Additionally, oxy-fuel torches exhibit superior performance when cutting thicker steel compared to plasma cutters. However, they can only cut through steel and other ferrous metals due to their reliance on oxidation.
In contrast, plasma cutters offer rapid cutting capabilities and may be considered safer since they don’t use gas or open flames. Each type of cutter provides distinct benefits tailored to specific professions.
Understanding the Inner Workings of a Plasma Cutter
What is a Plasma Cutter?
A plasma cutter is a machine that employs an accelerated jet of hot plasma to cut through electrically conductive materials. This includes steel, stainless steel, copper, aluminum, and other conductive metals. Plasma cutters find extensive use in industrial sectors such as automobile repair, marine salvage, and mechanical work sites.
How Does a Plasma Cutter Work?
The primary objective of a plasma cutter is to cut through conductive materials. But how does it achieve this?
The cutter generates an accelerated jet of extremely hot plasma that traverses the workpiece, resulting in a cut. The jet is created through the use of compressed gas, including air, oxygen, inert gases, and others, which is propelled through a small high-speed forced nozzle of the torch directed towards the workpiece.
Simultaneously, an external power supply generates an electrical arc that ionizes the gas, leading to the formation of the plasma jet. This high-velocity plasma jet supplies a substantial amount of heat, melting the material. The melted metal is then blown away by the compressed gas and high-speed plasma, facilitating the cutting process.
There are two types of plasma cutters: handheld torches and computer-controlled torches. Both serve their purposes effectively.
Handheld and Precision Operation
Handheld plasma cutters operate in a straightforward manner. When the machine is turned off, nothing occurs, as there is no contact between the electrode and the nozzle in the torch. The connection between the electrode and the nozzle, which are the consumable parts, remains inactive in the OFF mode, ensuring safety. When the machine’s trigger is pulled, a DC current flows through both the electrode and the nozzle from the power supply. This is also the stage when the plasma gas is introduced.
As the compressed gas builds up enough pressure to establish a connection between the electrode and the nozzle, they are forced apart. This separation triggers an electrical spark inside the torch, transforming the gas into a hot plasma jet. The DC current now flows from the electrode to the workpiece, rather than the nozzle.
In the case of precision plasma torches, the electrode and the nozzle are separated by a wire wrapped around the electrode. This wire induces a vortex shedding effect on the plasma gas. When the power supply is activated, an open circuit voltage of up to 400VDC is generated, pressurizing the gas within the torch. The swirling wire, separating the nozzle and electrode, helps create a vortex within the plasma gas. The initiation of the power supply results in an electrical spark from the arc starting console, establishing a current path from the electrode to the nozzle and creating a pilot arc of plasma.
Once the pilot arc touches the workpiece, the current path shifts, flowing from the electrode to the workpiece instead of the nozzle. The following section will explain why the plasma jet exhibits the characteristic shape that is commonly observed.
To achieve the desired amperage selected at the beginning, the power supply gradually increases the DC current. Additionally, fresh plasma gas replaces the pre-flow gas to optimize performance during the cutting process. Simultaneously, a shield gas flows from the shield cap, impacting and reshaping the plasma arc. This leads to a highly precise and swift cut.
Now you have a solid grasp of how a plasma cutter operates. The information provided above offers the best way to understand the functionality of a plasma cutter, regardless of whether you are a mechanic or not.
This powerful machine has the capability to cut through a wide range of electrically conductive materials, making it especially useful for intricate, curved, or angled cuts. Moreover, it excels in handling thick materials. The plasma cutter is simply remarkable.
If you have any further questions or need additional information about plasma cutters, please feel free to comment below and share your queries.