Guidelines for Buying a Plasma Cutter
Are you thinking of buying a plasma cutter? It can be a daunting prospect to purchase a piece of equipment which is new to you, especially with a lot of manufacturers and models to consider.
As a start, there are a few questions you should ask yourself:
> How long a day will you probably use your plasma cutter? In short, what duty cycle should it have?
> What type of electrical service is available where you plan to use it? Will it be 30 amp 110 volt single phase or 50 amp 220 volt single phase perhaps? What other equipment will be using the same circuit at the same time?
> What level of portability should your plasma cutter have? Will you take it outside or will you use it strictly in your shop? Will you be able to supply the machine with compressed air in a remote location? Air bottle or portable compressor? How can you provide electric current onsite?
> What material are you going to cut and what is its probable thickness?
> Manual cutting or with a CNC cutting machine? Usually, a higher amperage output would mean a greater duty cycle at a lower amperage. Many people believe that a greater-capacity machine is always better, but this is false. Fabricators often put oxy-fuel above plasma for cutting steel that has a thickness of .5 inch or higher; this has something to do with plasma-produced cut face which comes with a slight bevel (around four to six degrees). You won’t notice it in thinner materials, but as the thickness increases, it becomes more obvious. As well, at above .5-inch thickness, plasma has no advantage over oxy-fuel in terms of speed.
It would be almost useless to get a plasma cutter if acetylene will be used for the work anyway. If your intention is to cut aluminum, stainless or any other non-ferrous metal, which oxy-fuel cannot cut, get a 50 to 80 amp 220 volt plasma cutter. If you’re going to use your plasma cutter outside the shop from time to time, consider getting one of those new breed semi-portable types. These are tiny powerhouses that weigh no more than 100 lbs., but they can easily cut .75″ to 1″. You’re going to need a bottle of air or a compressor, as well as a portable generator.
If you think you may automate your plasma cutting at some stage, you should choose a unit that uses a low frequency starting circuit. A high-frequency start works like your car’s spark plug. Instead of using a comparably lower voltage pilot arc for initiating the plasma process, it depends on a high voltage spark, which brings about electrical interference such as destroying files, locking up the computer, destroying files, and the like.
Source: Plasma Cutter