The arc voltages listed in Hypertherm's cut charts are based on laboratory testing in actual cut conditions. The voltages are intended as a starting point ....and it is expected that the operator will adjust the voltage (once the rest of the cut parameters are set) so the the cut height of the torch matches the physical cut height (.062" or 1/16") required in the manual. Since arc voltage relies on a lot of variables....it can vary quite a bit from the book suggested values from system to system, and from cutting job to cutting job. Here are a few things that affect the voltage / height relationship:
- Cut speed....if you go faster at a given voltage...the torch will get further away from the plate, slower will be closer.
- Air pressure, air flow, air purity will affect height.
-condition of the table slates...dirty slats will make the torch run closer to the plate.
-condition of the consumables....nozzle wear and electrode wear will make the torch run closer. It is normal to have to increase arc voltage through the life of a set of consumables
Hope this helps.
Jim Colt Hypertherm