Answering how plasma cutters work requires comprehending both plasma and what a plasma cutter is. To understand the workings of a plasma cutter, our first consideration will be what exactly is plasma. When we think of the matter, we automatically imagine three states: solids, gases, and liquids.
These three forms can change into one of the other states if energy is introduced. Water in its solid form will be ice. If you heat it, it returns to water, and if you continue heating it, it will become vapor or steam, a gas. If heat is increased further, the gas becomes ionized and conductive electrically. It becomes plasma.
Plasma is the fourth state, after solids, liquids, and gases.
What is a plasma cutter?
This is a machine that allows you to cut through various materials including copper, stainless steel, brass, aluminum, or any metal that is conductive.
A plasma cutter uses gas that is electrically conductive to transport energy from a power source to any material that is conductive. A plasma cutter is a tool, that thanks to this transfer of energy, is able to cut through conductive materials more rapidly than other methods while producing a cleaner, more precise cut.
A plasma cutter contains three very important components:
The Power Supply
The power supply acts to convert AC voltage into DC voltage that is smooth and constant and ranges from 200 to 400VDC. The use of DC voltage is how a plasma arc will be maintained during the cut. It also has the task of regulating the necessary electric current output that is required for cutting. This will depend on the material you cut and its thickness.
The Arc Start Console
An Arc Start Console is responsible for producing a spark in the plasma torch from which the plasma arc is created.
The Plasma Torch
A plasma torch holds the consumable electrode and parts for generating the cutting arc. It must provide the correct alignment and allow for the cooling of the consumables used.
Each of these components has a fundamental part that is crucial to a plasma cutter’s functioning.
Are All Plasma Cutters the Same?
No, plasma cutters generally belong in one of two categories: precision and conventional plasma cutters. The main difference being that precision plasma cutters are produced to obtain the highest cut quality.
This type of cutter will use multiple gases as a plasma gas for specific applications. A conventional plasma cutter will use compressed air for the plasma gas of choice during cutting.
What is a CNC Plasma Cutter?
CNC signifies Computer Numerical Control. This kind of plasma cutter will have a torch mounted as part of the machine and will move the torch as directed by a computer. The “numerical control” refers to the fact that the motion of the plasma cutter is programmed through numerical coding in a computer program.
These plasma cutters will use a system that is designed for cutting that is mechanized and not handheld. They also use a type of torch that can be specifically held by the plasma cutter. These cutters also feature a control console or connect to a laptop or desk computer that uses an ethernet port for communication between the machine and the software.
CNC plasma cutters are often used to create signs, decorative work, and art for the outdoors or garden.
What is a Pilot Arc Plasma Cutter?
Better, advanced plasma cutters may feature a pilot arc as the cutting tool. When using a plasma arc cutter, the plasma takes the form of a gas stream that is electrically heated. This heating is so extreme that the stream of gas becomes ionized. Because ionized gas has the capacity to exchange electrons between atoms, this movement of the electrons allows the gas sufficient amperage for cutting.
The plasma arc cutter usually uses a plasma torch that has three main parts:
- Swirl or gas baffle
These are consumables because they will be consumed during plasma arc cutting and need to be replaced. When the plasma cutter starts up, the power source will energize the electrode. Gas will flow to the torch and will swirl using the baffle. Thanks to a generator, a spark will move between the electrode and the nozzle creating an ionized pathway through the gas. This pathway allows an arc to flow known as the pilot arc.
This arc flows out of the torch nozzle and makes contact with the material to cut creating the pilot arc.
The pilot arc plasma cutter lets you cut through a material without actually touching the material with the tip of the electrode. It also offers the advantage that it can cut through rusty surfaces, as well as painted and rough surfaces with efficiency.
Do Plasma Cutters Use Gas?
Yes, and there are several different gases that are used in plasma cutting. The most commonly used gas is simple compressed air because in many work environments compressed air is always on hand.
Do Plasma Cutters Need Gas?
Yes, plasma cutters do need gas, Plasma cannot be created without gas. Many plasma cutters will have multi-features that allow you to use various gases for varying applications. Usually, the choice of gas will be decided by the type of metal you wish to cut.
What Gas do Plasma Cutters Use?
This will depend on the material you want to cut and the thickness of the material, Various gases will achieve varying cut quality. The gases most often employed are argon, nitrogen, oxygen, or compressed air.
Argon is the go-to gas if you need to cut either aluminum or stainless steel because it offers the hottest temperature of burning plasma. Often in combination with hydrogen (65% argon, 35% hydrogen), it performs straight, smooth cuts. It can cut materials that have a thickness that is superior to three inches. It also performs well for plasm gouging on just about any material.
Nitrogen can also be used to cut both aluminum and stainless steel and provides an excellent quality of cut. It is particularly appropriate for plasma cutters that use high current and offers a top-quality cut for both mild and stainless steel with thicknesses up to three inches. You will often find nitrogen together with argon in use. It also performs well with CO2 for cut speed.
The gas that provides the fastest speed for cutting is oxygen, for this reason, it is the standard gas for steel cutting. Despite the speed, it offers excellent cut quality.
This gas is particularly indicated for carbon steel in thicknesses up to one inch and a quarter. When using on carbon steel, it does emit a spray of very fine molten metal. This gas works as a shielding gas. You can use it for aluminum and stainless steel, but the cut will appear somewhat rougher.
The most cost-effective alternative is clean shop air or compressed air. Because it is always available and free, it is as economical as gas gets. An air compressor is necessary, or your plasma cutter may come with a built-in air compressor. It is a versatile gas, especially for low-current cutting.
This cuts easily through mild steel, aluminum, and even stainless steel. It is also used for the plasma gouging of carbon steel. Moisture and dust particulates need to be removed when using. This gas is employed for materials up to an inch in thickness.
When considering gases for plasma cutting, factors to consider include type of material, cut quality, and cost.
What Can a Plasma Cutter Cut?
A plasma cutter can only cut metals and alloys that are conductive, and a conductive metal is a metal that is able to transmit heat or electricity. However, some metals may not be as easy to cut as others due to the metal’s melting point.
Metals that a plasma cutter is able to cut through include:
- Cast iron
- Mild steel
- Stainless steel
What Is Plasma Cutter Gouging?
Gouging is the technique to use if you need to remove a defect in your material or an older weld. This will require a specific gouging tip. Most of today’s plasma cutters have the capability to gouge along with cutting.
A plasma cutter is a state-of-the-art tool that uses electricity and pressurized gas to cut metals that are able to conduct electricity. The plasma cutter works by creating a pathway that is electrical and extremely heated of ionized gas, or plasma. The plasma originates in the torch and streams through the material needing cutting.
The electricity completes a circuit to return to the plasma cutter thanks to a clamp for grounding that attaches to the piece being cut. Various gases are employed when using a plasma cutter and the choice will depend on the material to be cut and the thickness of that material.
Using a plasma cutter, whether entry-level or a more advanced cutter, can make cutting metals so much easier and faster, saving you time and money.