Different Methods Of Plasma Cutting
Matter exists in four different states – solid, liquid, gas and plasma. Plasma is an ionized gas that can conduct electricity. It is the fourth state of matter. Plasma for cutting is created by adding energy to an electrically neutral gas. In this case, the gas is compressed air. The energy is electricity. With the addition of electricity, the gas is electrically imbalanced and like a wire will conduct electricity. It is now plasma. It is similar to the wire in a light bulb. The more electrical energy pushed through it, the hotter it becomes.
The plasma can be controlled and concentrated to a single area. Added air pressure and intensified with higher voltage creates plasma arc cutting. This is more than melting metal. It is an art of blasting through the cuttings away. This is plasma arc cutting. If the plasma torch is tilted, it is known as plasma arc gouging.
By controlling the plasma and concentrating it to a single area and adding air pressure, any electrically conductive material can be cut without preheating. This includes aluminium, steel, copper, brass and even titanium.
There are many techniques of plasma cutting. Care must be taken while doing so. The improper piercing technique is the number one cause of premature failure in the various parts of a plasma torch. Others include inadequate plasma flow, inadequate coolant flow, and PAC machine malfunction.
What is needed for plasma cutting?
- Power source – must have drooping characteristic and high voltage.
- Gas composition – oxidising gases can be used. Plasma gas flow is vital.
- Dual gas – in the conventional system, a tungsten electrode is used. The plasma is inert. Oxidised gases are used. The dual gas system operates in a similar manner. The difference is that a secondary gas shield is utilised around the nozzle.
Plasma technology has been in commercial application since the early 1960s. The advantages and use of this technology have been increasing ever since.
- HD cutting to over two-inch thickness
- Improvement in the hole accuracy in the past three years
- Ease of application has increased in the past five years.
- ‘cut to cut’ productivity has been enhanced in the last five years
- Technology of structural shape cutting and bevelling has improved radically
Relative Process Technology Levels
- Oxy-Fuel Technology has remained dormant in the past fifty years or so but is not likely to go anywhere. The technology utilised in Oxyfuel is similar. It is mounted on the same CNC machine as the plasma cutter. The automated gas flow and the processes of the gas cut have shown more improvement. The technology in the control of the torch height has also shown vast improvement which improves the accuracy and control.
- This process is essential for the processing of the productive plates of steel which has a thickness of over two inches.
- Laser cutting is nothing but carbon dioxide laser technology which is applied in the cutting of metal. It has been stable in its use for the past twenty-five years or so. This is a technology that has been continuously evolving. Fibre laser technology will soon overtake the carbon dioxide laser process.
The advantages are immense.
- It is faster
- Ease of application
- Maintenance costs in the longer term are reduced after the switch from carbon dioxide to fiber technology
- Fiber technology can be used more on machines designed conventionally
- The thickness levels of the productive plates are increased because of the power levels of the fiber laser
- Abrasive water jet is another technology that continues to evolve simultaneously
The advantages increase because of the improvement in the engineering and the technology as well
- Low maintenance costs due to the advancement in the intensifier ability
- Higher reliability due to increasing the water pressure
- Advancement in the water jet nozzle
- Edge angularity improvement leads to cut quality enhancement
- Ease in overall application of the technology
Improvement in automation and reduction of the operation costs is improving due to the advancement of the abrasive water jet technology.
New models are introduced in order to start a revolution of the cutting technology. The efficiency depends on the size of the plasma arc and the nozzle. The CNC machines are very unique. High-speed movements and sharp monitoring by the computer controls ensure high accuracy and efficiency. The CNC machines have gained high industrial acceptance because they are a well-preferred technique for cutting metals.
Manual plasma cutting systems operate on relatively small power supplies. It uses hand-held torches for cutting metals. They are versatile. It is used in shops that handle thin metals and construction works, shipping manufacturers, and auto repair work. A manual system is picked depending on the thickness of the metal to be cut and the required speed of cutting.
Mechanized plasma cutting is essentially larger than the manual plasma cutting systems. Mechanised systems have a Computer Numerical Controlled (CNC) plasma cutting and a Torch High Control (TNC).
Computer Numerical Controlled (CNC) plasma cutting is the process in which metals of different thickness are cut with the help of a plasma torch. This is done with the help of inert gas or compressed gas that is blown through the nozzle at high speeds. The electric arc that is formed from the gas is utilized to cut the metal. The cutters are of different price, size, and functionality.
Mechanized plasma cutting is used in robot cutting and laser cutting. The size is based on the table and the gantry being utilized. These systems cannot be manoeuvred with ease. It is vital to consider all components before installation. The overall layout of the factory also needs to be taken into consideration.
Compressed air is used as the plasma gas and an assist gas. The preferred plasma gas is an argon or hydrogen mix. This is used for cutting steel and aluminium.
Plasma cutting is seen as cost efficient and versatile. Rapid cutting speeds and high accuracy promotes this technology.