Bevel

Jim, What would cause the flame to be narrower at the bottom of cut than the top? New table with powermax 85, all cuts appear to be beveled out at bottom. All parts new, lots of clean dry air. Using 45 amp. Everything set per Hypertherm manual. Thougth I had a bevel out problem until I cut a 1 & 5/8" hole. Hole is beveled in and slug is beveled out telling me my arc is wider at top than at the bottom. Cutting 1/4 mild. Only thing not per manual is perice delay set at .1 instead of .6 per Tom. Come to think of it I had this problem even when I was using .6. Any ideas?

Plasma cutters, all of them, cut wider at the top as compared to the bottom of the kerf. We control angularity as well as possible by using a clockwise gas swirl which makes the right side of the cut (when the torch is driving away from you) squarer than the left. When cutting holes...there is a lag in the arc as well that causes the bottom of the hole to be smaller than the top. You can diminish this a bit by cutting holes at a slower speed (rule of thumb is that holes under 1" should be cut at 60% of the recommended cut speed)...but you cannot eliminate it...especially with an air plasma.

There are systems that cut with far less taper as compared to an air plasma...Hypertherm has the HPRXD (available in 130, 260, 400 and 800 amps) industrial high definition class plasmas ....the 130 starts at about $30k, the 800 is close to $100k (just the plasma). Versions of these HPR systems can be used with "True Hole" technology....which almost completely eliminates taper in holes.

The Powermax85 will provide better holes than any other brand of air plasma....but keep in mind that air plasma systems are the lowest cost form of plasma cutting. The cut quality cannot be compared to the high definition class versions of plasma.

jim Colt

Quote:

Originally Posted by 383nova66

Jim, What would cause the flame to be narrower at the bottom of cut than the top? New table with powermax 85, all cuts appear to be beveled out at bottom. All parts new, lots of clean dry air. Using 45 amp. Everything set per Hypertherm manual. Thougth I had a bevel out problem until I cut a 1 & 5/8" hole. Hole is beveled in and slug is beveled out telling me my arc is wider at top than at the bottom. Cutting 1/4 mild. Only thing not per manual is perice delay set at .1 instead of .6 per Tom. Come to think of it I had this problem even when I was using .6. Any ideas?

Thanks Jim, You always have the answers when it comes to Hyertherm. As always, you've been a big help.