Plasma Welding Review: Guide

Evolution of Plasma Cutters


The fabrication industry depends greatly on welding and gas cutting technology. With continuous innovations, this field of applied engineering has made spectacular advancement, both in theory and in technology of application. One such unique advancement is seen in the metal cutting technology. Till recent times metals were cut by conventional gas cutting using acetylene and oxygen. But after the advent of the fourth stage of matter the cutting technology has undergone a revolutionary change.


The Theory Of Plasma Cutting

We all know that there are three stages of matter namely solid, liquid and gas. But when the gas is superheated a fourth stage of matter is found which is known as plasma stage. Heating increases the speed of movement of the molecules and atoms of gas. At one stage the energy forces the molecules and atoms to break apart. We know that inside every atom, electrons orbit round its nucleus in various orbits.

All these happen due to forces of attraction and repulsion as well as centrifugal and centripetal forces among the orbiting electrons and the nucleus. But high input of heat energy destroys this balance, forcing the electrons to furiously move around. The electrons will collide with other electrons and ions creating enormous energy. The plasma cutters employ this theory to revolutionize the metal cutting process.


The invention of plasma cutting technology dates back to the times of World War 2 when it was invented as a faster way of welding the war machines like tanks, aircrafts etc. in the ensuing years, a lot of research has been done on the technique of plasma cutting altering and changing the characteristic properties of plasma jet making it useful under specific conditions.


They altered the operating parameters like gas type, voltage, current, size of the nozzle and current. Because of this now a days there are certain plasma cutters which can easily cut through metal plates of 10 inch thickness. The plasma cutters have periodically lost and regained their charm, but being one of the major technological innovation and having brought so many radical changes in the process of metal cutting it must be studied that’s why in many of the international schools of the world the subject of metal joining and cutting is taught with proper emphasis on Plasma cutting technology so that the budding and future technocrats can understand no only the technology but also its relevance and role in changing a process making it so easy over the years.


The first type of plasma cutters invented were very big in assembly and very time consuming when assembled. Known as the conventional plasma cutters they generated plasma jet by conventional “dry” arc constriction technique. The efficiency was not very high and because of its size the usability was limited.


After half a decade of its introduction came the air plasma cutters, which used atmospheric oxygen to provide provided additional energy on an exothermic reaction with the molten work piece. This added energy resulted in 25% increased cutting speeds than before. But because of its inability to cut steel and aluminium these types of plasma cutters lost their usability.


After that came the water injected plasma cutters in which water was injected into the arc radially. It offered a higher degree of arc constriction. 50,000 K of arc temperatures was reached which was more than twice the temperature of the earlier plasma cutters.

After this, plasma cutters were invented which used air as the plasma gas and were operated at low-amp conditions. This is considered as a major turn-around in the market of plasma cutters which increased many folds.


Then came the high density plasma cutters; because of the invention of laser cutters which were proving to be the biggest competitors and threat to plasma cutting technology, there was need to mould plasma cutters in such a way that it can match the precision cutting and quality of laser cutters, thus they invented high density plasma cutters. It was designed ina way that high quality plasma could be produced at 40 to 90 amps, resulting in a squarer cut at high cutting speeds.

As the technology increased and computer took over, the design of plasma cutters was also altered incorporating the computers making the process easy and less cumbersome for the users. Plasma cutters which coupled the plasma cutting technology with the CAM software resulted in the complete automation of the process. These computer aided plasma cutter are very big in size, expensive and used only in industries.

Nowadays, most of the plasma cutters are portable from the standpoint that it can be carried on a truck and taken anywhere. Some of the portable plasma cutters are so light that they can be carried with ease. Units are starting to appear in the market with in-built air compressors that make the whole system mobile and compact.


Safety Tips For Safe Plasma Cutting


Plasma cutting is highly efficient and easy way of welding but it comes with lot of hazards like emission of poisonous gases, UV rays, excessive consumption of electricity, etc. This process requires proper precautions and safety wear to accomplish it in effective manner without any harm or damage. In this article we are discussing few safety factors that you must keep in mind before starting plasma cutting welding.


 Fire Hazards

The plasma cutting arc produces sparks and heat especially during the initial piercing of the metal. Therefore, it is important to wear safety glasses to protect your eyes from its hazardous impacts. Moreover, face helmet with safety glasses are required to increase the protection level.

To protect your body from the hot metal and flying sparks you should also wear flame-resistant clothing and gloves. The clothes are made of woven materials like leather, heavy denim etc. that play well in providing good protection. Avoid wearing cuffed pants because it can easily catch the spark and increase the risk of fire. High-top leather shoes and boots are recommended to use for best foot protection.


 Keep The Surrounding Free From Flammable Materials

The heat and sparks can ignite the flammable material spread over the welding area and lead to fire accident. Therefore it is advised to keep all the flammable things away from the cutting area to minimize the chance of any mishap. Keep the fire extinguisher in your reach so that you can easily use it if any fire related problem arises.


Dim The Lights

Arc rays can produce intense rays that can burn the cornea of your eye and also leave negative impacts on the skin. Proper clothing can help in protecting your skin but your eyes need extra protection which is provided by the face shield or safety glasses fitted with correct lenses shades. To determine the proper lenses shade you need to check the amperage capability of your machine.


 Proper Ventilation


Metal cutting can produce fumes and gases that cause breathing problems and health hazards. You should keep your head out from the fumes and do not breath them. Therefore it is important that place where you want to do welding should be fully ventilated for the proper supply of air.


Advantages Of Using Plasma Cutters For Welding

Plasma cutting machine is mainly used by auto shops and car manufacturers to design chassis and frames. Even it is also extensively used by construction companies for accomplishing large scale projects for cutting and fabricating large beams or metal sheet goods.


Benefits Of Using Plasma Cutters

  • The easy use of these cutters increases its importance when it comes to accomplishing the industrial work. As compared to other manual tools it requires less operator training.


  • Secondly, it has great ability to offer finest quality work. These cutters have excellent capability to cut both ferrous and non-ferrous metals.


  • It offers smooth edges to metals after cutting


  • They are portable and designed with latest technology. There are many products available in the market but plasma cutters are portable and come in variety of sizes and shapes.


  • They are economical and can be purchases within the budget.


  • Beneficial in saving utility bills as it uses less power in comparison to others.


  • Plasma cutting machines are available two varieties — manual and automatic. You should choose the machine type as per your requirement to get desired results.


How Plasma Cutter Works

The CNC plasma cutter is just one of the countless inventions that were developed due to the increased demand for factories during the Second World War. The breakthrough discovery was that inert gas could be combined with an electric arc in order to create a powerful welding tool. Since this time these machines have gone through many changes. It was discovered that because they could reach much higher temperatures than the typical welding tool, they could actually be used to cut through thick sheets of metal like a saw. This invention has improved the speed, accuracy, and the types of cuts that could be used in the manufacturing process.

The secret behind the CNC plasma cutter and its ability to cut through thick sheets of metal is due to the unique properties that plasma possesses. Most people are familiar with the three stages of matter, liquid, gas, and solid, but did you know there is a fourth stage, plasma? This stage is reached when the gas is heated to an even greater extent. This occurs when the energy actually begins to break apart and the molecules of gas and the atoms split as a result. The electrons separate from the nucleus and begin to move around furiously. The electrons will then collide with other electronics and ions which will create vast amounts of energy.

There are many different shapes and sizes of CNC plasma cutter table available which range from small, handheld tools to massive robot controlled machines capable of making the most precise incisions. However, no matter what size, they all operate in the same manner. Pressurized gas is sent through a small channel which contains a negatively charged electrode. A spark is then generated which heats the gas until it reaches the plasma state of matter which is so hot (30,000 degrees Fahrenheit) that it turns metal into a molten slag.


A cutter nozzle is designed with many different outlets which protect the cut from oxidation and regulates the plasma which can be very unpredictable. A constant stream of shielding gas is released around the cutting area from these channels which ultimately controls the radius that the beam travels on.

Today CNC plasma cutter machines are found in a wide variety of applications. Auto shops and manufacturers use them to easily create chassis and frames and construction companies use them for projects that require them to cut through huge sheets of metal. They are now affordable enough that hobbyists can use them in their DIY projects. They can even be used by locksmiths to bore through massive safes and locks.


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