What Size Compressor do I need for a Plasma Cutter?
Plasma cutters are used for construction works, welding, auto mechanics, and general household chores that involve cutting of metals. Ideally, all plasma cutters require an external air compressor to operate. However, there are few plasma cutters with an inbuilt air compressor, but the vast majority will need a separate air compressor. The greatest advantage of a compressor with a built-in compressor is the ease of use and portability, but most are only designed to cut thin metals.
When looking for an air compressor to use with your plasma cutter, you'll need to consider the air pressure and airflow requirements of your cutter. The air compressor you choose should be able to meet these requirements' failures to which your machine's performance will suffer a great deal.
How much air does a plasma cutter require?
Air requirements for a plasma cutter vary from one model to another, but the general rule is, the bigger the compressor, the better. Ideally, you'll want to buy a compressor whose CFM rating is higher than your plasma cutter or one that is rated about 1.5 to 2 times the CFM of your cutter to ensure that your machine doesn't stop temporarily when the air compressor takes time to refill.
When it comes to the air pressure (PSI rating), the recommended operating pressure varies from one brand to another, but most are rated at 90-120PSI. The air pressure required will depend on the type of material, material thickness, and type of job. For instance, cutting usually takes less pressure than gouging, so you must refer to your manuals to determine the correct settings for your machine.
Scope of cutting
Generally, your air requirements will depend on how much cutting you are planning to do. For instance, small plasma cutters often have air requirements of about 4-5 SCFM at 90 PSI. You can use such units to cut up to a 3/8-inch steel plate. Medium-sized units, on the other hand, require about 6 SCFM at 90 PSI with cutting width of 3/8″-3/4″. Heavy-duty units take about 7-9 CFM at 90 PSI, typically used for ¾"-1 ½" steel cutting.
For most DIY projects or an occasional weekend hobbyist, getting a compressor with CFM rating slightly higher than the plasma cutter will be adequate. As such, you can get away with a small 20-gallon air compressor as long as you don't use your plasma cutter for an extended time. However, you need to keep in mind that your compressor may not be able to keep up when you need to make longer cuts.
If you do a lot of plasma cutting for large-scale operations, you'll require a unit with a large tank, such as a 60-gallon air compressor that's capable of double the plasma system requirements or at least 1.5 times greater.
Does the quality of the compressed air affect cut quality?
The quality of the compressed air is crucial for plasma cutting. If there is moisture or oil in the compressed air, it will affect the cut quality. Unfiltered air also makes you burn through the consumable pretty fast and your equipment won't last for long. These consumables include the nozzle, electrode, shield, and the retaining cap. So, when using compressed air, you'll want to ensure your air stays dry and as clean as possible. You can achieve this by draining your compressor as often as possible or adding an external filtration system to help absorbs and remove the contaminants.
The air filter/dryer is placed between your plasma cutter and air compressor to help to reduce the amount of moisture and particulates fed through the airflow into your plasma cutter. Using an air dry will also save money in the long run and the amount of time spent replacing the consumables. The dryer can be maintained by changing the filter inside after long periods of use.
Finding the correct size compressor for your plasma cutter should not be a hard task as long as you know the air requirement ratings of your machine. All you need is to consider your usage plans, and always remember the general rule; match the air compressor to the plasma cutter and not the opposite. If the compressor is too small, you could burn out your compressor or starve the cutter, thus losing efficiency. In addition, if the quality of the air is substandard, you'll have poor quality cuts, and you could damage your equipment as well. So, at the end of it all, you'll want to make sure that that your air supply meets the demands of your plasma cutter.