A Quick Guide to Buying a Plasma Cutter
Are you planning to buy 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.
To start with, answer the following questions before you go out shopping:
> How hours of daily use will the equipment get? What duty cycle should it have in other words?
> 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? Ca you supply the machine with compressed air when you bring it to a remote location? Air bottle or portable compressor? How about supplying the supply electric current at the site?
> What kind of material would you like to cut and how thick might it be?
> 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. Plenty of people think that a machine with greater capacity is always better, but not necessarily. Fabricators usually consider oxy-fuel as superior to plasma for cutting steel that have a thickness of .5 inch or more; this is because of the 4 to 6-degree bevel in the cut face made by the plasma. It is not obvious in thinner materials, but it becomes more noticeable as thickness increases. At thickness above .5 inch, plasma also bears no cutting speed advantage compared to oxy-fuel.
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 from time to time, consider getting one of those new breed semi-portable types. These units are small powerhouses weighing under 100 lbs., but they can cut .75″ to 1″ in a pinch. You would need a a bottle of air or a compressor, with the addition of a portable generator.
If you automating your plasma cutting is a possibility, then get a unit that which doesn’t use a high-frequency starting circuit. A high-frequency start works like your car’s spark plug. Rather than relying on lower voltage pilot arc to begin the plasma process, it counts on a high voltage spark, which produces electrical interference like computer lockup or destroying files, etc.
Source: Plasma Cutter