The ratings for air plasma systems for hand cutting as compared to machine cutting are different because:
1. Piercing capability. Typically on a cnc machine the torch is mounted perpendicular to the plate, and above a certain thickness the molten metal that is blown back during the pierce will damage the fron t end consumable parts on the torch. Most cnc machines have a torch height control system that will set a higher pierc height, then index down to the proper cut height, but even with this piercing is limited. With the torch in your hand, you can tip the torch at a steep angle so the molten material will not damage the front components on the torch.
2. Duty cycle ratings. Typically in mechanized applications the torch is used more and cycled more, as the operator does not tend to get tired. If a machine is retaed for 40% duty cycle at it's full output, then it in theory can cut continuously for 4 minutes and must cool for ten minutes on its thickest rated material, on a day that the ambient temperature is at the same temeperature that the manufacturer rated the machines duty cycle at.
3. On very thick materials the speed of a plasma torch drops off considerably. 10 inches per minute is not especially slow for hand cutting, but is agonizingly slow for machine cutting!
It has been kind of a rule of thumb to rate most air plasma's for mechanized cutting at 1/2 the rating for hand cutting for the above reasons.
So, for mechanized cutting, the thing to pay careful attention to is the piercing capability. If you need to pierce 25mm material, then you will need to specify your plasma system to be able to do so, or you will experience very low consumable parts life.
The important things to look for:
1. Pierce capacity.
2. Cut speed capability on thicker materials
3. Consumable life claims
4. Killowatt output and duty cycle (not just Amperage!)
You will notice that the T-D units have a relatively low duty cycle, and if you dig into their literature you will see that a unit with equivalent amperage as compared to other brands (Hypertherm as an example) will have a much lower output killowatt rating. (calculated by multiplying Amps x load volts)...and this means lower speds and lower duty cycle.
If you can edge start, you can do 25mm materials with most machines in the 80 to 100 amp class. Most of these machines are rated to pierce about 19 mm.
Take a look at Hypertherm | Plasma Cutters | Plasma Cutting Equipment | Metal Cutting Equipment for the most powerful industrial grade plasma systems!