Guidelines for Buying a Plasma Cutter
Are you planning to buy 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.
To begin with, there are a few questions you should answer before going shopping:
> How often in a day do you plan to use the equipment? In other words, what duty cycle do you need it to have?
> What electrical service type is available in the area where you will be using the machine? Is it 50 amp 220 volt single phase, or maybe 30 amp 110 volt single phase? What other equipment will be sharing the circuit with the plasma cutter?
> How much portability are you looking for? Will you take it outside or will you use it strictly in your shop? Do you have way of supplying compressed air to the machine when you take it to a remote location? Will you use a portable compressor or an air bottle? How about supplying the supply electric current at the site?
> 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 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). It is not obvious in thinner materials, but it becomes more noticeable as thickness increases. Also, plasma has no advantage over oxy-fuel in terms of speed at thicknesses beyond .5 inch.
It would be almost useless to get a plasma cutter if acetylene will be used for the work anyway. 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’re going to use your plasma cutter outside the shop sometimes, you have to consider getting one of new breed of semi-portable types. These are little powerhouses weighing below 100 lbs., but they have the ability to cut .75″ to 1″ in a snap. You would need a a bottle of air or a compressor, with the addition of 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 is like your vehicle’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