By system ratings, we don't mean the number of stars given to our product, but rather the cut capacity ratings Hypertherm has for its systems. If we say "System X has a recommended cut capacity of X inches," what do we mean? The word "recommended" seems to throw people off, but really all it means is that is the thickness you can cut while still getting the best cut quality. Let's use the Powermax65 as an example. As you can see below, the chart (found on our website) shows two different recommended cut thicknesses. Typically the top number, which in this case is 20mm or 3/4", refers to the thickness you can cut while moving your torch at a relatively fast speed and still getting good cut quality.
The speed we most often (but not always) use is 500mm, or the equivalent of 20 inches, per minute. Now, if you need to cut material thicker than that you still can. That's where the other numbers come into play. For example, if you need to cut 25mm or 1" thick material, you can and you will still get good cut quality. That's why 25mm (1") is also listed as "recommended." However, as you'll see in the "cut speed" column, you need to slow down to a speed of 250mm, or 10 inches, per minute.
The next row you see there refers to our severance capacity. "Severance" is the thickness of metal you can get through. Know though that the cut quality won't be good (in fact, it's bound to look downright ugly!) and you will have to move your torch at a much slower speed. The chart above tells you that you can get through 32mm or 1-1/4" inch thick material using the Powermax65 but you will need to move your torch at a very slow 125mm, or 5 inches, per minute.
Finally, the last row. Pierce capacity is the thickness of metal you can pierce through. When we say pierce, we mean stationary piercing. Your torch is in a stopped position above the metal before moving straight down and piercing the metal. In the case of the Powermax65, we are telling you that you can pierce 16mm (5/8") thick metal.
Note that some manufacturers sometimes use moving pierces rather than stationary pierces, which allows them to list a higher thickness, since moving pierces are easier to do.
Hopefully this explanation is helpful. If you have questions not answered above please list your questions down below in the comments section.