Cut Quality

[miketodesca]

Hi,
I am running a 4 X 8,PPLLC gantry, Candcnc control, Hypertherm 65 power supply with a machine torch. I have been having trouble maintaining consistent quality cuts throughout the lifetime of the machine, about 3 years! I can run 2 parts from the same sheet of steel using the same settings and get 1 part that looks great, and the other is junk. I mostly run production, 50+ parts at a time. I need to cut some plates from 5/8 HRS material, and need to get good cuts and decent consumable life. I am wondering if there is anyone in Mass. who is running a similar machine and would be able to give us some direction,and possibly some hands-on help getting this machine running right.

Thanks,
Mike

[jimcolt]

If you get a change in cut quality from one part to the next......without changing any settings or parameters....then I would suspect that the torch nozzle is likely getting damaged from piercing. One pierce too close to the material will create a notch in the perfectly round orifice.....which changes the shape of the plasma arc. An arc that is not perfectly columnar will cause varying cut edge angularity.

I am guessing on this as you have not described the material thickness, the power level, the settings or details of the cut quality issues (angularity, dross, dimensional changes, out of round holes, etc.?).

I use a Powermax85 (same cut quality as a Powwermax65) and can cut hundreds of parts on a nest with very nice repeatability from part to part.

I suspect something is either changing in your height control (likely pierce height or pierce delay) or it needs to be adjusted to ensure that piercing is done more consistently. Good closeup pics of the nozzle, the shield (after some use and cut quality issues) as well as pictures, descriptions of your cut quality issues will go a long way towards getting some good help.

Best regards, Jim Colt Hypertherm

[miketodesca]

Thanks for the reply, I have been following the feeds/speeds outlined in the manual. I have tried slowing it down as well, but nothing changes. I have done everything as far as setting and re-setting everything several times, but the result is always the same. I believe we are close, but in the process it has cost a lot in scrap material, consumables etc.It has gone from a "spare time project" to something that I now need to produce.

Just cant get this machine where I want it.

Thanks,
Mike

[jimcolt]

I understand that you may be following the specs in the operators manual....however are you 100% sure that when you set a pierce height of say..... .15" (as the manual may suggest for a particular thickness) that the pierce height is actually .15"? This is a very common error.....there is a method on some machines to verify that the settings produce the desired result (hysteresis setting for the "floating" z axis plate sensor switch). If not set correctly.....you will ruin a nozzle orifice in 1 or 2 pierces.....and you will get widely varying cut angularity.

There are a few of us on this site with many years of cnc plasma cutting under our belts....I have 36 years. Happy to help, however you need to tell us what is wrong....and be patient as we try to troubleshoot the symptoms. From what you mentioned.....it sounds like you are getting one good cut, then inconsistent results. We can fix that if you can provide some good feedback!

Jim Colt Hypertherm

Thanks for the reply, I have been following the feeds/speeds outlined in the manual. I have tried slowing it down as well, but nothing changes. I have done everything as far as setting and re-setting everything several times, but the result is always the same. I believe we are close, but in the process it has cost a lot in scrap material, consumables etc.It has gone from a "spare time project" to something that I now need to produce.

Just cant get this machine where I want it.

Thanks,
Mike

[miketodesca]

I am looking for advice from experience. I am sure I am in the right place. I have checked the height several times with an .050 gage block, and it seems to be good. I can get you pictures or whatever you may need to get the problems solved. I have been getting around the quality issue by cutting oversize and machining, but there are instances where I need to get parts off the plasma finished.

Thanks again,
Mike

[jimcolt]

Maybe you can describe the cut quality issues......looking at the original and subsequent posts all I see is "having trouble maintaining consistent quality cuts" and "1 part that looks great, and the other is junk ". These statements do not describe cut quality issues with any level of accuracy.

If you could provide details like:

- Cut edge angle varies widely around the cut perimeter...
-Cut edge angularity is excessive, but consistent around the perimeter....
-Cut parts are oversized (or undersized).....
- There is heavy dross on the bottom.....
- There is dross on the top.....
- The cut edges are very serrated around the cut perimeter....
- The cut edges are serrated on diagonal cuts and on holes.....
- The first cut is meets my expectations, but the second and subsequent cuts are showing drosss and excessive, varying angularity.
- The nozzle is completely destroyed after xxxxx number of cuts at 45 amps.
-The shield orifice is getting damaged after 6 or so pierces.....

These types of descriptive statements will help us help you. Pictures of the shield and nozzle with closeups of the orifice after a "bad" cut will help as well. You have good equipment, there is no reason why you cannot get excellent cuts like most other do!

If you prefer to work directly with me, my email is jim.colt@hypertherm.com

Jim Colt

Best regards, Jim Colt