need help hyperther 1250 w/phc lift

[woodman08]

we are still having problems every second or third cut seems ok ,no changes on settings used all recommended settings from jim colt.
It will always cut the same so if its missing a bit it will do the same miss each time.Seems now the torch firing is pausing and that the bit it misses.
I still feel the problesm are in the phc unit ,something off spec.Ran the cnc with no torch and it traces out the full pattern and the torch says put.
We have gone through many sheets 16 guage steel and have had to manually touch up or cut a lot of the pieces by hand to complete them .
We are located in southwestern ontario so there is no support here .
We have switched to all new consumables ,nothing has helped to the point where its reliable

[nomedia="http://www.youtube.com/watch?v=t10Xeo2V9Ok"]YouTube - good cut bad cut[/nomedia]

[woodman08]

"1. Lets start fresh with new consumables in the Hypertherm torch....make sure they are a good match for the material that you would like to cut.

2. Choose some material....perhaps some 1/4" mild steel plate, and then program a simple part such as a 4" x 4" rectangle.

3. I would choose the 40 Amp consumables (and look at the machine cutting chart in your Hypertherm manual) 120930 shield, 220061 retaining cap, 120932 nozzle, 120926 electrode, 120925 swirl ring.

4. Make sure the ohmic wire from the PHC is attached to your retaining cap.

5. Use a programmed cut speed of 48 inches per minute, set the pierce height to 1/8" to 3/16" (3 to 5 mm) , pierce delay time to 1 second, cut height to 1/16" (1.5mm), and amperage to 40 Amps, and set arc voltage to 149, these settings are all out of the Hypertherm manual, and I know they work....with possible exception of the arc voltage as that varies from installation to installation.

6. Do an IHS test (the instruction manual will tell you how to do this...this will confirm the pierce height is correct).

7. Do a first test cut and carefully observe the torch to work distance....it needs to be 1/16". If too high, lower the arc voltage setting on the PHC, if too low, raise the arc voltage setting until it is just right.

8. Once the height seems correct, do another sample cut. If the height control is rising off the plate or crashing into the plate....then lets put the height control in manual mode and do another cut with the torch at a fixed height of 1/16", to do this you will have to ensure that your plate is level....so that 1/16" is maintained all around the cut perimeter.


Things that can go wrong and cause an arc voltage height control to provide inaccurate height:

1. If the cnc on the cutting machine settings are incorrect. The cnc must provide a height freeze signal in all corners, in small (under about 1" diameter holes) that locks out the arc voltage control to eliminate diving in these areas, the diving is due to the z , y axiss slowing down for cornering. If you see the torch dive and drag in corners, on kerf crossing, and in small holes and fine features...then you will need to revisit the arc voltage interface settings in your software.

3. If you are cutting along and the torch rises off the plate.....if it rises and stops at a certain height but keeps cutting....then simply lower the voltage setting until it is at the right height. If it continues to rise randomly, then there could be an issue with the pHC internally.

4. As consumables wear, expect the torch height control to move the torch coser to the plate. It is normal with any plasma/thc to have to increase the arc voltage as the consumables wear...in order to maintain the proper torch to work distance.

5. If the torch dives and drags often...and simply increasing the arc voltage does not work, and you are sure the cnc is freezing the height in corners and during decelleration...then check your work ground to your cutting table, a loose connection can cause thc diving. On some plate, such as small pieces or thin materials and especially aluminum, it is a good practice to have a welding cable with one end attached to the grounding (work cable connection) and the other end with a 100 amp welding clamp that can attach directly to the material you are cutting.

Please try the above, or at least report back to me with more detail and I'll try to help you out. You have a great plasma and THC system, I do not know much about the rest of the machine! perhaps with a little step by step testing, and new consumables are a must, then we can isolate where the issues are coming from.

If there would be a calibration issue wioth the Sensor PHC....the above tests will help us out. On this type of system it is important to set the arc voltage to whatever setting gives you the physical height required in the Hypertherm cut charts. The voltages listed in the cut charts are recommended starting points....but vary from site to site as there are at least a dozen variables that affect the relationship between voltage and height with any arc voltage height control system. Regardless, if there is an issue with part of the Hypertherm system we certainly will stand behind it as we always do.

Best regards, Jim Colt Hypertherm

we did this and the cuts did improve but not 100%

[jimcolt]

From what I can see....it appears that the cut program starts moving before the torch fires. That tells me that the cnc control is not waiting until the arc transfer output from the plasma indicates that the arc current has transferred to the plate.

The arc transfer output from the plasma is an internal current sensor that measures cutting current through the work cable. If the arc has not fired....there is no current. When current is sensed, a relay closes, (pins 12 and 14 on the machine interface receptacle on the Hypertherm rear panel)....and this signal should be wired to an input on the cnc control (I don't know anything about your particular machine.....so I'm not sure how it is supposed to be wired) that only allows machine motion in the xand y directions.....when the arc is transferred. Consequently, if the arc extinguishes mid cut, the motion will stop as well.

If I had the overall wiring digram for your machine...I could probably help troubleshoot this.....from the video I would surmise that the arc transfer output is simply not connected, and if the arc start is delayed (there are a few things that can cause this) then the machine motion will start anyway.

Here is the way it is supposed to work:

1. CNC moves the torch into the position to start the program.
2. CNC sends cycle start to the height control.
3. Height control indexes down to sense the surface of the plate.
4. Once plate is senses, THC indexes up to the operator set pierce height.
5. Once at pierce height, the THC sends a start contact closure to pins 3 and 4 on the plasma.
6. It takes about 1/4 second under normal circumstances for the plasma to fire and the arc to trnsfer to the plate.
7. When arc transfer current is sensed, pins 12 and 14 on the plasma connect....these connections go to an input on your cnc control, and machine motion should be allowed. If for any reason the plasma extinguishes, pins 12 and 14 open, and motion should immediatly stop.



To me it sounds like the arc transfer input (some machine manufacturers call this "machine motion enable", or "arc good". It appears to me that your motion is starting perhaps after a time delay.....and if the plasma start somehow delays, the machine starts to move without it. This could be simply not wired, or perhaps the function is not activated in your software.

If the torch is occasionally getting a start signal, but is not firing almost immediately...then it could indicate that 1. The retaining cap is overtightened, 2. The retaining cap is worn and needs replacement, 3. The swirl ring need replacement.

Jim Colt

[woodman08]

The whole torch assembly consumables have been replaced quite a few times.Its zeroed each time before it fires,We have used the same files (good vector files) and in this case the letter S cuts perfect and the letter O does not and you could re-do these cuts and it will duplicate the fault to the nearest 1/32 inch in each case.
Flashcut is the post processor and the file is brought into flashcut and it in turn generates the g code and does the cut,in all tests if there is a good cut we would try different patterns certain patterns cut fine
I attached a table layout picture you see the letter N did not complete,the deringer cut did not complete the number 2 did not complete.
Is there some setting we have overlooked.
I have looked through the falshcut manual and cannot find anything
BUT we do appreciate your interwest Jim

stan kern

[jimcolt]

Stan,

It is clear to me what is happening from the video and the pictures. For some reason.....either it is not wired, or it is not activated in your software.....the arc transfer, or arc good signal from the plasma to the cnc is not functioning. Once you determine whether it is a wiring issue or a software issue....then it will be easy to fix. Determine and trac pins 12 and 14 from the plasma system all the way to the cnc.....if they are connected, look at your schematic and determine if they are connected in the right locations. Also, check your software to see if there is an "Arc Good" or "Plasma Arc On" or "Machine Motion" input that needs to be activated. It should be looking for a contact closure from the plasma to indicate that the arc is cutting the metal......if the wiring is correct and this function is not activated.....then that will be your problem. There is no delay in either the THC or the Plasma that can do what seems to be happening in your video...as long as the above is connected and activated.

This signal when interfaced correctly will not allow the machine to move until the plasma arc has started cutting the plate.....and will solve your incomplete cut problems.

As I said before.....do you have a wiring diagram or a schematic of the plasma/THC/CNC interface for your machine? And what is the operating system...is it Mach3?

You could replace the THC and Plasma......but you will have the same issue from what I can see in the video!

Jim

Jim

[woodman08]

We have all the manuals for the 1250/phc and flashcut ,but that has not helped ,flashcut does not seem to be popular with plasma so to ask people about setting is like talking greek.
But if what you're saying is possible then why does the machine cut sometimes perfectly then others not .
Its to the point that if we want a certain cut you just sort of bank on a good day.Its not consistent,just when you smile and think some thing different you've set then the machine does a bad cut,we spend a lot of time touching up cuts ,yet when you look at the S letter being cut you could not ask for better performance.
The manufacturer of this machine (gorilla out of london ont) closed up shop 2 months after it was delivered (approx) and the help we get is from people like yourself and others off the zone offering suggestions and we have pretty well exhausted all avenues.
In the long term we might be better off under mach3,now it is possible that because all the electrics are in one box we're getting interference(the computer was removed earlier on) so now its the phc eltronics ,flashcut board and a break out board on top of 2 drives and a power supply.
It certainly looks like a can of spagetti when you remove the lid ,but taking the built in computer off line i feel was a good idea.
Its disheartening like having a new car that can't get out of the driveway

[jimcolt]

I cannot explain why it would cut some shapes well and others not so well. That has to be a machine coding issue on those parts. I would compare the code line to line between a part that works repeatably and one that doesn't.

As far as the motion of the machine going without the plasma on......I say for the third time.....that cannot happen if the wiring is correct and the software settings are correct. You need to check the wiring as I suggested, and you need to find someone that is familiar with the software that you have....for help with the setup.

Jim

[woodman08]

Thanks for your time we'll plug along