85A CNC Bolt Hole Speed Setup

[alabamaranger]

Anyone have a good chart for cutting bolt holes in thicker plate such as 1/4", 3/8", 1/2" and 3/4"?

I tried to cut some 3/8" holes in 3/8" plate. The holes came out funnel shape. I was running about 50ipm at 122V - 85A.

Thanks

[JJsCustomDesigns]

Theres 2 ways that i cut holes.

1. I have the plasma pierce the center of the hole and i drill it to size.
2. I use 1/3 to 1/2 the normal cut speed. Say 1/4" plate is 50ipm. I will use 25ip . If i still dont get the desired outcome ill try 1/3 of 50ipm.

Sometimes its just easier to center mark them with the plasma and drill them to size.

[alabamaranger]

Thanks, is there any difference in the FineCut consumables on small holes?

I notice on the Hypertherm manual it has different speed rates for shielded and non-shield consumables, which mine is shielded.

1/4" Shielded = 130, Non-Shielded 1/4" = 120, so 1/2 of 130 of the shielded would be 65.
3/8" Shielded = 70, Non-Shielded 3/8" = 60, so 1/2 of 70 of the shielded would be 35

Might need to do another test plate with holes having each hole at a different speed - 35, 40, 45 and see what happens.

[jimcolt]

Rules of thumb for best quality holes:

1. Always use the lowest power that can cut the material thickness....refer to the plasma system operators manual. I cut 1/4" and 3/8" plate with excellent quality holes with my Powermax85 using the 45 amp shielded process. (note...the Powermax85 operators manual does not list cut specs for 3/8" using the 45 amp shielded process...so I use the specs from the Powermax45 manual.

2. Always cut holes under 1-1/4" diameter at 60% of the recommended speed for the material being cut.

3. Always lock out the arc voltage height control on holes under 1-1/4" diameter. Let the height control find the plate , retract to pierce height (exactly as manual suggests, pierce, then move to cut height (exact height manual suggests), then proceed with cut, but with THC in "manual" mode.

4. Holes should be programmmed with a long lead in as this allows the arc to pierce and stabilize height and plasma gas pressures before reaching the actual hole profile. A spray of mig welding anti spatter spray on the top of the plate will minimize top slag....which will produce a better hole.

5. There should be no lead out. It is better to either stay on the hole radius and stop at the kerf crossing point.....or even better to program an "overburn"....which stays on the hole radius past the kerf crossing point about .150"...then extinguishes the arc.

Some pictures of holes cut with my Powermax85 on a PlasmaCam machine, 1/4" plate as well as 1/2" plate....holes are as cut using above techniques.


Jim Colt

Anyone have a good chart for cutting bolt holes in thicker plate such as 1/4", 3/8", 1/2" and 3/4"?

I tried to cut some 3/8" holes in 3/8" plate. The holes came out funnel shape. I was running about 50ipm at 122V - 85A.

Thanks

IMG_2948.jpg (51.09 KiB) Viewed 1366 times

IMG_2948.jpg (51.09 KiB) Viewed 1366 times

IMG_2360.jpg (48.32 KiB) Viewed 1366 times

IMG_2360.jpg (48.32 KiB) Viewed 1366 times

[alabamaranger]

Thanks, on the 85A are you using a 45 amp torch Nozzle (220941) or using the 85 Amp Nozzle at the 45 Amp settings?

In the 45 Amp Book it states:

3/8 Mild Steel, Cut Speed is 32, so did you cut the holes at 19.2 ?
1/2" Mild Steel, Cut Speed is 20, so did you cut the holes at 12? Manual recommends it states to edge start. So did your pierce it ok?

Does it make any difference if the hole is cut counter clockwise or clockwise?

[jimcolt]

Yes....60% of the suggested speed on the holes...you have the correct numbers. Using an 85 amp nozzle at 45 amps will produce a very bad cut quality......use the 45 amp shielded consumables at 45 amps....this provides the best energy density for best edge squareness.

If you have a good height control that can set an accurate pierce height and can set a pierce delay time...then you can pierce 1/2" all day long with the 45 amp shielded consumables. I use a .22" pierce height with a 1.3 second pierce delay time.


Jim Colt

Thanks, on the 85A are you using a 45 amp torch Nozzle (220941) or using the 85 Amp Nozzle at the 45 Amp settings?

In the 45 Amp Book it states:

3/8 Mild Steel, Cut Speed is 32, so did you cut the holes at 19.2 ?
1/2" Mild Steel, Cut Speed is 20, so did you cut the holes at 12? Manual recommends it states to edge start. So did your pierce it ok?

Does it make any difference if the hole is cut counter clockwise or clockwise?