Hypertherm true hole technology

[rikduk]

Im wondering mr. Colt, for the best holes possible, you say to use a straight lead-in,
but when looking at true hole, they use an arc lead-in. Why?
Is it because of air plasma vs hy-def plasma?

[jimcolt]

True Hole auto switches from oxygen plasma with air shield to oxygen plasma with oxygen shield as soon as the pierce is complete. The characteristics of an oxygen/oxygen high definition plasma arc are very aggressive, in fact instantly the kerf width doubles in size. So....this process uses canned lead in shapes that utilize 3 velocity changes during the lead-in which controls the bottom position of the arc very accurately to minimize taper, dings and divots. The process is very robust and produces some amazingly nice hole quality.

When I am talking about getting the best hole quality out of an air plasma....or any plasma that does not use the TrueHole processes, then I suggest the straight lead in because it seems to work best on a mechanically tight machine with decent acceleration. If you have a machine with terribly slow acceleration or mechanical backlash....often you will be better off experimenting with a radial lead-in.

The keys to minimizing the dings and divots associated with the lead in kerf: high acceleration, accurate torch to work distance, mechanically tight machine (no backlash).

The keys to minimizing the dings and divots associated with the end of cut (arc off/motion stop): Coordinated overburn and arc off timing while machine motion continues.

The keys to minimal taper in holes (assuming you don't have True Hole): using the lowest power level consumables for the material thickness, running at approximately 60% of the recommended cut speed, accurate torch to work distance.


Jim Colt Hypertherm

[rikduk]

Thank you!