First determine your plasma cutting machine rate and the rate indicates the inches a cutter can cut per minute. It depends on two things such as metal type and amperage. Amperage generally deals with how much the electric current can pass between the two conductors. Higher the amperage, larger the arc it produces. Metal types have the chance of affecting plasma cutters rate because different metals has the capability to conduct electricity at different rates. It is a general fact that metals with higher conductivity can cut quickly than metals with lower conductivity. Your workshop or home electrical output should match with your plasma cutting equipment requirement. Duty cycle of the welder is essential and you need to buy the welding machines with proper duty cycle.
It is a known fact that duty cycles generally indicates how many metals it can cut per particular time span and also how long does it takes to cool down before cutting the other machine. For example, a plasma cutting machine that cuts for 3 minutes requires 9 minutes to cool down if it has 20 percent duty cycle. Similarly the cooling rate varies based on the duty cycle of the welding machine. Portability is what you need to determine and remember that even small amps welding machine can weigh more. If you have decided to buy a powerful welder, then be sure that you do not relocate very often so that you remain hassle free. The high amp plasma cutters generally require an air compressor that provides a continuous stream of air for ongoing steady arc. For welding jobs that are small, you can use compressed air bottle that are less powerful and also, you can use low amp plasma cutter. The general fact is that you need to replace each bottle as it gets empties.
Make sure that the plasma cutting machine you busy suits within your budget and if you buy for small jobs, then buy the mid range plasma cutters or if you are going to buy for some big purposes, then buy the high amp plasma cutting welding machines that suits your budget.