Metal cutting falls into two categories: mechanical cutting and thermal cutting. Plasma cutting is a thermal method that uses ionized gas to cut the metal. Plasma cutting is one of the most used techniques for cutting thick metal plates, and it is also often used for cutting sheet metal.
With the use of plasma cutting machines, it becomes easy to do things like manufacture parts and create works of art. Read on to find out more about the origins of plasma cutting machines, how plasma cutting machines work, what their advantages are, and what their functions are.
Buying Plasma Cutting Machines
First things first. If you are looking to purchase a plasma cutting machine, you have two options. You can either buy a brand-new machine or a used and refurbished machine.
You will find refurbished plasma cutters with a variety of capacities and lengths from leading brands like Hypertherm, Hornet, and Messer. Refurbished machines provide the same quality as new machines, but they are less expensive to purchase.
A Brief History of Plasma Cutting Machines
Plasma cutting machines first emerged in the 1960s. They became more productive at cutting metal sheets and plates in the 1980s. The early machines were pretty slow and expensive. They were also very large.
Therefore, they were mostly used for cutting repeated patterns in mass production. Things changed in the late 1980s with the introduction of Computer Numerical Control technology.
The CNC tech used in plasma cutting machines enabled the cutters to have greater flexibility for cutting different shapes. However, the machines were still limited to cutting parts and patterns from flat steel sheets with only two axes of movement.
In recent years, manufacturers have created plasma cutting machines that have smaller nozzles and a thinner plasma arc, which has enabled high cutting precision.
How does plasma-cutting work?
Basically, plasma cutting works by using a jet of very hot plasma to cut workpieces made of electrically conductive materials, such as aluminum, steel, stainless steel, copper, and brass. With a temperature of up to 30,000 °C, it is easy to see how powerful plasma cutting machines are.
The process involves creating an electrical channel of the superheated, electrically ionized plasma gas. It emits from the plasma cutting machine to the workpiece that requires cutting and then forms a circuit back to the plasma cutting machine via the earth terminal. The process is achieved by a compressed gas that is blown at high speed to the workpiece via a focused nozzle.
Within the gas, an arc forms between an electrode by the nozzle and the workpiece. The electric arc ionizes part of the gas and creates an electrically-conductive channel of plasma.
As the current from the cutting tool flows through the plasma, it emits enough heat to melt the workpiece. At the same time, the hot molten metal is blown away by the compressed gas to separate the workpiece.
Mechanized plasma cutting machines are typically a lot larger than manual ones, and they are used with cutting tables. Large mechanized cutters can be integrated into a laser, punching, or robot cutting system.
What is the maximum thickness plasma cutting machines can handle?
Handheld plasma torches can typically cut up to 38 mm of thick steel, while stronger plasma cutting machines can cut up to 150 mm of a thick steel sheet. But it is not only about the thickness.
In addition to being able to cut both thin and thick sheets of metal, plasma cutting machines can cut sheets in curved or angled shapes. That is due to the plasma cutter producing a very hot temperature.
Different Types of Plasma Cutting
Not every plasma cutting machine works in the same way. One plasma cutting method is known as high-frequency contact. The method uses a high voltage and high-frequency spark.
That is created when the plasma touches the metal. Another method is the pilot arc technique. The arc is created after a spark is produced via a low current circuit with a high voltage.
When the pilot arc comes into contact with the workpiece, the cutting arc is created. You can also use a spring-loaded plasma torch head, which creates a short circuit so that the current can begin to flow. The pilot arc is produced by releasing the pressure. The arc is then brought into contact with the workpiece.
Functions of Plasma Cutting
Plasma cutting machines are used in many different industries for various purposes. They are used by welding repair centers and metal service centers and are used in industries like construction, commercial shipbuilding, agricultural maintenance, trailer production, and automotive repair and restoration.
Because of plasma cutting’s precision and high speed, it is widely used from the largest of industrial companies to small hobby companies.
The Advantages and Disadvantages of Plasma Cutting
While plasma cutting has many advantages, there are some drawbacks to using plasma cutting machinery. Some of the key advantages include the following:
- You can cut any electrically conductive material.
- You can attain high-precision and repeatability.
- You can cut materials like aluminum and high-alloy steel in a range of thicknesses.
- You can cut high-strength structural steel with lower heat input.
- You can attain high cutting speeds, which are up to ten times faster than using oxyfuel methods.
- You get a smaller cutting kerf compared to the process of flame cutting.
- By using plasma cutting underwater, you get very low heat exposure and a low noise level.
The disadvantages of plasma cutting include the following:
- Plasma cutting machines have relatively high-power consumption.
- New plasma cutting machines are more expensive than oxyacetylene cutting systems.
- Plasma cutting machines can be noisy when dry-cutting.
- Tolerances are not as high as with laser cutting.
- You get a wider kerf than with laser cutting.
Whether you are a professional manufacturer or a hobbyist, the above information should make it clear that plasma cutting machines offer many advantages for cutting both thin and thick sheets and plates of metal. They provide high precision and quality finishes, and they can be less expensive than other metal cutting tools.