Guidelines for Buying a Plasma Cutter
Are you thinking of buying a plasma cutter? Its can be overwhelming to purchase equipment that is new to you, not to mention there are so many models and manufacturers and models to select from.
As a start, there are a few questions you should ask yourself:
> How often in a day do you plan to use the equipment? In short, what duty cycle should it have?
> What type of electrical service is available where the machine will be used? Is it going to be 50 amp 220 volt single phase or maybe 30 amp 110 volt single phase? What other machines or tools will be run on the same circuit simultaneously?
> How much portability are you looking for? Will you use it strictly in your shop or outside as well? Will you be able to supply the machine with compressed air in a remote location? Will you use a portable compressor or an air bottle? What about the electric current onsite?
> What material are you going to cut and what is its probable thickness?
> Will you only do manual cutting exclusively, or will you probably use your plasma cutter with a CNC cutting machine? Usually, a higher amperage output would mean a greater duty cycle at a lower amperage. A lot of people think that a higher-capacity machine is always better, but this isn’t true. Fabricators generally consider oxy-fuel to be better than plasma for steel cutting steel with a thickness above .5 inch; this is due to the slight (4 to 6-degree) bevel in the cut face produced by the plasma. It is not obvious in thinner materials, but it becomes more noticeable as thickness increases. As well, at above .5-inch thickness, plasma has no advantage over oxy-fuel in terms of speed.
If you’ll be using acetylene for the work, there will be nearly no point in purchasing a plasma cutter. If you intend to cut non-ferrous metals like stainless or aluminum, which could not be cut by oxy-fuel, think 50 to 80 amp 220 volt plasma cutter. If you must take your plasma cutter outside the shop, get one of those latest semi-portable machines. 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 operates like the spark plug in your vehicle. Instead of using a relatively lower voltage pilot arc to start the plasma process, it relies on a high voltage spark, which causes electrical interference like destroying files, locking up the computer, and so on.
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