Both plasma cutting and Oxyfuel systems have their advantages and disadvantages. To make a decision which system to use depends on factors such as thickness and material type, power resources available, cost and location of the job. The metal cutting is a common step involved with many welding-related jobs, whether the application is in a fabrication shop or on a Jobsite.
Which process will ultimately yield the lowest cost per cut after considering all the variables, plasma or oxy-fuel? In Oxyfuel cutting a fuel natural gas heats the metal to its kindling temperature, where a high-pressure stream of pure oxygen rapidly oxidizes and blow away the metals. This process works well with carbon steel because iron oxide melts at a lower temperature than steel. The Oxyfuel does not work with Aluminium because it melts at a very high temperature, and it won’t work with stainless steel as it does not oxidize.
The high precision plasma process works with an electrically conductive material, making it suitable for cutting steel, stainless steel, and aluminum. It heats the gas to an extremely high temperature and ionizes it so that it becomes electrically conductive, allowing the electric arc to transfer to the workpiece, and thus the force of the plasma and shielding gases blow away the molten metal to cut the workpiece.
Cost Factor Consideration: At first instance, we might think that many factors seem to favor the Oxyfuel process, which is why it has been the preferred cutting technique with many fabricators for decades. The availability of extremely fast piercing and cutting speeds of high precision plasma systems, the choice now is not very clear especially on material less than 1.5mm in thickness.
Low-cost Oxyfuel: The Oxyfuel cutting requires very little capital to implement and operate. A machine torch set up including hoses, and all accessories cost around Rs 28000and a multiple torch set can still cost less than Rs 60000. A cutting tip cost approximately Rs1200. Most of the Oxyfuel use LPG which is very cheap. The oxygen is the single largest operating cost for the Oxyfuel process. Once installed the gas system operates almost maintenance-free. Other than changing consumables, the torch, gas distribution and manifold system are extremely robust.
Its primary limitation is its relatively low piercing and cutting speed. The torch may cut up to 30 inches per minute(IPM) on thin material, but the speed level out around 15 IPM on material 2 inches in thickness. The Oxyfuel provides with an advantage when the same pattern can be cut in parallel, which enables using multiple oxyfuel torches up to eight on the same gantry is not very uncommon.
An automated plasma system 10 times costlier than the Oxyfuel system. Its torch consumables cost more too. The consumables do not last long as compared to Oxyfuel. The high speed of plasma cutting provides an economic advantage as plasma cutting equipment is available up to 400 amp plasma system. which increases travel speed on medium thickness material and remains competitive with Oxtfuel on steel up to 2mm in thickness. The cost per foot is 5times more in Oxyfuel than plasma cutting system. The application involving part nests and workpieces requiring multiple pieces also more suitable for plasma system as plate doses, not requires preheating as in Oxyfuel As a result of higher capacity and higher speed, plasma now is commonly found useful in heavy equipment, pressure vessels, ship, rail, and other fabrication operations which were previously the domain of Oxyfuel.
Additional Pros and Cons of each process: Oxyuel torches are available in extended length to keep the operator at a distance from the heat, flames, and slag produced while cutting. The Oxyfuel torches are used with 75 to 150 ft hoses which can sometimes the length of hose maybe 200 ft. Plasma cutting system can offer benefits for cutting thinner ferrous metals, including shaped metals like angles, channels, and tubes. The plasma cutter has a better ability to cut the large volume of thin sheet metals, and offer the fastest grate cutting capacity. It also does not require strong or explosive gases resulting in a safer job site.
Conclusion: Most people are looking or some sort of “rule of thumb” which can be used when deciding whether a part should be sent to a plasma cutter or a burning machine. We have the following suggestions.
a) Regardless of what size plasma you have, use plasma for anything up to maximum production piercing capacity up to 2 inches thick.
b) Use Oxyfuel for everything over 1 inch thick if it has only 1 or 2 pierces, and can be cut with at least 4 oxyfuel torches. Otherwise, use plasma.
We hope it may act as a guide for the age-old question but you feel free to talk for any clarification, addition or deletion of any technical part.