Tips 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 start with, answer the following questions before you go out shopping:
> How hours of daily use will the equipment get? In other words, what duty cycle do you need it to have?
> What type of electrical service is available where the machine will be used? 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?
> How portable do you need the equipment to be? Will you use it strictly in your shop or outside as well? Do you have way of supplying compressed air to the machine when you take it to a remote location? Will you be using an 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?
> Will you only do manual cutting exclusively, or will you probably use your plasma cutter with a CNC cutting machine? Generally, the greater the plasma cutter’s amperage output , the greater the duty cycle will be at lower amperages. Plenty of people think that a machine with greater capacity is always better, but not necessarily. 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. You won’t notice it in thinner materials, but as the thickness increases, it becomes more obvious. At thickness above .5 inch, plasma also bears no cutting speed advantage compared to oxy-fuel.
It is almost useless to buy a plasma cutter that cut 1.5 plate, if you will be using acetylene for the work anyway. If the plan is to cut non-ferrous metals such as aluminum or stainless, neither of which can be cut by oxy-fuel, go for a 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 might automate your plasma cutting in the future, pick a unit that that runs on a low-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
