Hypertherm powermax 65 cutting problem

[jimcolt]

Can you post a few pics of the torch nozzle (that was used for one of the bad cuts) and shield, good closeups of the exit orifice on each. Your Powermax65 will cut best if you follow the operator manual cut charts exactly, especially the choice of consumables, pierce height, pierce delay time, cut speed, amperage and cut height and arc voltage. Be sure you adjust the arc voltage from the book setting....go higher or lower on voltage in order to maintaine the correct torch to material distance. Jim Colt Hypertherm

[Danny78]

Hi jim thanks for your response. I have been starting all my cutting as per hypertherm recommendations and don't seem to be having much luck. I tried some fine consumables over the weekend and couldn't have asked for a better result, but like with the standard consumables I had to lower the amps and speed to achieve a good result. Today I tried the fine consumables again and it cut nothing like it did over the weekend, I tried new consumables but no luck. When cutting at hypertherm specs I can get a very low dross cut but bevel is severe ,if I try and lower the arc voltage to get closer to the sheet the THC bounces around, if I raise the arc voltage bevel and dross increase.It puzzles me as to how over the weekend I cut nearly a full 3mm sheet of mild steel and it cut perfectly, minimal dross and close to zero bevel then today without any changes being made it cut terribly

[Danny78]

3mm mild steel ,parameters that seemed to work best was 35amps,arc voltage 90v. Cutting speed 1600mm/minute or 63"/minute

[jimcolt]

If your THC is not keeping the torch at the correct height (usually .060") and is bouncing....I suspect that once that is fixed you can get the edge taper down to a useable level. If the torch is too high expect severe bevel, if the torch z axis (height control) oscillates, expect serrated, rough edges. Wrong height and oscillation will cause you to have to slow down below the recommended book specs.

I stand 100% behind the book specs. stray from any one of them and you'll find yourself off on a tangent tweaking all of them to regain expected cut quality. I have been plasma cutting for 40+ years.....the book specs in the Hypertherm manual are where ZI cut 95% of the time.

To solve oscillation on a z axis: 1. Be sure there is no backlash in the drive mechanism. 2. Experiment with using a slower z axis speed. 3. Detune the acceleration settings. (I don't know what machine / height control you are using, so you should refer back to the mfgr. to get help on these things.

Once oscillation is fixed....ensure that when you set the arc voltage that you do a test cut (book speed and amperage) at the cut height (usually .06") with the THC off or in manual mode. Read the arc voltage. That is the voltage that will maintain .06", and will give you the best cut quality at book speeds and amperage. Don't worry if the voltage that achieves the cut height is different from the cut chart voltage (the difference in voltage is simply calibration in the electronics....it does not matter, so set the voltage where the physical cut height meets the book cut height, that is what matters.)

Best edge angularity will occur when using the lowest power nozzle that will cut your material thickness. 45 amp shielded will do a better job on 1/4" steel than 65 amps will. 45 amp fine cut will do a better job on 10 ga than the 45 amp shielded will. (book specs, run at the right height with no z axis oscillation.

Amperage settings that allow you to run at book speeds and with minimal dross and angularity are the rated amperage for a given set of consumables. Yes, you can find a happy setup at less than 45 amps on a 45 amp nozzle.....but you will have to do a bunch of experimenting to find it. Why not use the book specs that were developed by process engineers for the best combination of angularity, minimal dross and consumable life....Hypertherm has already done the experimentation for you. Just remember, the height control has to work correctly for any of this to work as designed! Jim Colt Hypertherm

[Danny78]

Hi Jim I have spent all day testing cuts in manual mode and auto mode. I first set the torch height .060" 1.5mm from the sheet then tested to hypertherm specs first cut came out great the second did not cut through cleanly at all I continued different cutting tests with the THC in manual mode and auto mode throughout the day with mixed results, I just cant seem to work this out I didn't alter from hypertherm book specs today . I tried with standard 65amp consumables and finecut consumables. One thing I did notice while doing the manual test and watching the arc voltage was the reading was exactly book specs then on the next cut +10v more, this happened all day,does this sound normal to you ?

[WyoGreen]

I just finished reading thru all the posts on this thread, I didn't find where anyone asked about your air supply. Your last post sounds a bit like an air supply problem. So are you monitoring your air pressure at the back of your plasma cutter to ensure it is staying within your cutter parameters?

Steve

[jimcolt]

If you did one cut with the THC off at a known height (measured with a thickness gauge from material to torch) and at a fixed speed, air pressure and amperage........then did a second cut , did you recheck the height with a thickness gauge?. If nothing else changed (speed, air pressure, amperage) yet you saw 10 higher voltage then that says your height was 10 volts higher (each volt on your system is roughly .004", so that means the torch height increased by .040", which would make a rather ugly cut. If you are 100% sure the distance between the torch and plate stayed at exactly .060" for both cuts and you saw 10 more volts....then either the speed changed, the air pressure changed, the amperage changed or maybe your height control readout changed by 10 volts. Height is critical, that's why these machines have height controls.

Is it possible that the heat input from the first cut cause the material to bow downward? Is it possible that something caused the z axis to move upward .040"? Something is happening that is causing your voltage to change, and since voltage is proportional to height, then you have to assume the height is changing. Jim Colt Hypertherm

Hi Jim I have spent all day testing cuts in manual mode and auto mode. I first set the torch height .060" 1.5mm from the sheet then tested to hypertherm specs first cut came out great the second did not cut through cleanly at all I continued different cutting tests with the THC in manual mode and auto mode throughout the day with mixed results, I just cant seem to work this out I didn't alter from hypertherm book specs today . I tried with standard 65amp consumables and finecut consumables. One thing I did notice while doing the manual test and watching the arc voltage was the reading was exactly book specs then on the next cut +10v more, this happened all day,does this sound normal to you ?