Clean holes

[sonofmitch]

I'm running a Hypertherm HPR400XX with a Burny 10. My ID holes all come out with a "skin tag" at the lead in/out point on the bottom side. How do I eliminate this or at least improve it.
SonofMitch

[jimcolt]

If you had the Hypertherm HPR400XD on a machine with a Hypertherm cnc control and ProNest software...you would be able to use the True Hole technology that automatically eliminates hole taper and the ding and divot associated with the lead in and lead out on your holes.

The Burny controls do not have this capability, however if you can post some pictures of the issues with your holes....and let me know what CAM nesting software you are using...I may be able to help you make improvements!


Jim Colt Hypertherm

I'm running a Hypertherm HPR400XX with a Burny 10. My ID holes all come out with a "skin tag" at the lead in/out point on the bottom side. How do I eliminate this or at least improve it.
SonofMitch

[sonofmitch]

Jim,
These pictures are of 1/2 inch stainless burned on 400amps. The slots are 5/8 inch. I am using ProNest 2012 and these occur on parts that are not cad drawn but are standard shapes

Mitch

[jimcolt]

OK, I did not realize you were cutting stainless.....our True Hole process only works on steel as it uses an oxygen based exothermic reaction.

Anyway....in order to get these slots to cut better you will need to draw them. The standard shapes in the Burny system are all very conducive to oxy-fuel burning of steel....they do not work well with plasma cutting. The parts will need a lead in from the center scrap....I would recommend trying both a straight lead in and a radius lead in to see what works best on your machine. The radius lead in tends to work better on machines that may have sluggish acceleration and the straight lead in on machines with great acceleration.....all factors of the drive tuning as well as how well the drives are matched to the mass that is being moved. The lead out at the end of the cut must be an overburn....meaning that the torch must stay on the cut path (no lead out into the center scrap) past the lead in kerf by about .200", and if your controller and CAM are capable....do an advance off (plasma off) so the the plasma shuts off exactly at the lead in kerf crossing...yet the motion continues as much as .200" past this point.

The cut speed should be about 60% of the recommended cut speed from the manual. If the straight sections of the slot are most important...do your lead in and overburn on one of the radius' at the end. Further...if you want best quality ...this 1/2" should be done at either the 130 amp or the 200 amp process level....400 amps is good for high speed cutting...but not at all good for intricate detail work such as holes or slots.

Hope this helps


Jim Colt

Jim,
These pictures are of 1/2 inch stainless burned on 400amps. The slots are 5/8 inch. I am using ProNest 2012 and these occur on parts that are not cad drawn but are standard shapes

Mitch