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Cutting rates on Robofil 510

mflux_gamblej

Plastic
Joined
Jan 18, 2013
Location
CO, USA
I'm pretty new at this forum, am on another forum more in the past for cnc milling.

I'm having trouble with my wire edm having slow cutting rates and a servo that wants to keep ramping the cutting speed and always just breaks the wire. I'm able to get like 1.1 to 1.5 in^2/hr by limiting the speed with the S parameter so the wire wont break.

have tried stratified and half hard brass, similar results in terms of cutting rates.

I'm not able to seal the nozzles to my parts due to the nature of the parts. The robofil 510 is supposed to cut at 20+ in^2/hr though (i assume with sealed nozzles and ideal conditions). Something is up with this machine, any experience out there to suggest what to look at?

the machine contacts upper and lower to the table measure 220ohm, the table to machine gnd measures about 60kohm. the water filters are pretty new / all 10 running, the upper head is in very clean condition I rebuilt it a few times already. The lower head has new pinch rollers. contact wetting is good in the upper head.

It seems that when the machine runs the %ST / protections strategy up higher like at 70%+ I dont get wire breakage right away and can cut faster, but as soon as that decreases the %machin. just keeps ramping and goes from 1 or 2 up to 12 to 15 and then the wire just breaks. Seems like a servo problem or .tec problem? maybe one of my boards is on its way out?
 
I’m assuming this 510 is non submerged? How thick is the part? You may need to adapt the pressure settings of top and bottom nozzle to get the coverage required.
I don’t want to teach you to suck eggs, but the highest pressure doesn’t always mean best pressure.

On the 310 I normally reduce the FF parameter to 50 from 100 then work it back up if I get breakages.

And yes, top and bottom nozzles sitting flat with full pressure and using roughing cuts will give the quickest speed. However sometimes it just has to be accepted that slower cutting is the only reliable way.
 
I’m assuming this 510 is non submerged? How thick is the part? You may need to adapt the pressure settings of top and bottom nozzle to get the coverage required.
I don’t want to teach you to suck eggs, but the highest pressure doesn’t always mean best pressure.

On the 310 I normally reduce the FF parameter to 50 from 100 then work it back up if I get breakages.

And yes, top and bottom nozzles sitting flat with full pressure and using roughing cuts will give the quickest speed. However sometimes it just has to be accepted that slower cutting is the only reliable way.

This was a 0.8" piece. I ran the INJ at 1, about 2 bar or so.

The machine seems to have a routine that lowers the protection strategy %ST when the machining servo %Machin. reaches near zero. You can see the machine limited by S sitting around 7 to 8 %Machin. Then if you increase S a small amount until %Machin. goes near zero, then %ST lowers, say from 70% to 66% and at that point, %Machin. is now like 20 or so and in this fashion the machine just keeps on ramping up the speed if you dont limit it and breaks the wire. This happens in a matter of seconds if you dont limit the speed with S.
 
I did notice that if I used the wrong .tec file, and stratified wire on this piece, the results were better in terms of speed.

I was running half hard brass and a .tec file from CT Expert that matches the conditions except sealed nozzles. I got about 1.2in^2/hr or the wire would break if faster.

I switched to stratified wire and resumed a program, not bothering to load a stratified .tec such as UXS25A.TEC. I just kept on using the CT Expert tec for the half hard paired with copper material (my work piece was copper). Under these conditions, I was able to ramp S up to a point where I could get about 2.6in^2/hr and at one point I got as high as 3.8 in^2/hr but it didnt last. It was stable at around 2.6in^2/hr. If you let it servo without the S limit, %ST goes down and %Machin. just keeps on ramping and breaks the wire all the same.

But I did get much higher cutting rates with that mis matched setting.

The difference is this:
UXS25A has V-80 IAL 16 Aj 40 B6.8 A0.9 Tac 0.4
myUHHBCU.TEC had V-80 IAL 8 Aj 55 B7.8 A1.1 Tac 0.7

I had cut on this part a while ago with stratified using that UXS25A.tec as shown above and got like 1.something in^2/hr so clearly there's an issue with either the tec vs the conditions, or maybe my machine's sensing circuits are broken or something.

I am unaware of how to manually make a .tec file that has programmable V and IAL.

does this info spark any thoughts for anyone?
 
looks like you can make a custom .tec by using 'USER.TEC' and all parameters are specifiable. would be nice if you could do this on your computer and load it into the memory instead of standing at the control and typing the values. The .TEC files look like they're encrypted or encoded or something though if you just try and edit one in notepad.

at any rate its an aside to the main question about getting good cutting rates. something must be wrong if the charmilles tec files make the wire break constantly right? are there some trim pots on the UA/SAL board or somewhere else that need to be re-tweeked after so many years?
 
the 510 generator does need periodic tune ups. How are your cables inspect them and make sure the terminations are good.
 
the 510 generator does need periodic tune ups. How are your cables inspect them and make sure the terminations are good.

Hi I have rebuilt the connections in the upper and lower head, and have taken apart the cables on the wall side to check the sensor cable - the connections are covered with brown edm dirt but underneath the connections were clean. My machine has the mecatool replacement table in it which discards the sheet metal covers on each side near the walls. That exposes the cables to edm dirt moreso than if there was some sheet metal there. That being said, I measure 220ohm which is what I was told the resistance should be by gfms and by reading forums. I am unsure what the resistance between table gnd and machine gnd / mains earth should be. I measure something near 60kohm, maybe it should be full open circuit? If you have a 510 that's cutting faster than mine would you check that number?

About a generator tune up, I'd really like to know the procedure. I've been quoted a pm that includes things like replacing wire guides, other guides, and the usual upper and lower head consumables. They didnt mention a generator tune up.

There are some values that need to be checked or set according to the maintenance manual, being:
1.) mains voltage 380V+10%/-15%
2.) 'CT voltages' with QS1 off 5(4.8 to 5.2), +12V(11 to 13), -12 (-13 to -11), 24V (23 to 24), 40V (34 to 45)
3.) triggering voltage 120V+/-6V
4.) UPR regulator voltages boards 1-4 all 170V+/-2V and RUPA board 120V+/-2V
5.) well voltage off-load (80V to 89V) 'source E3'
6) mean current with short on wire, then correct IAL, then check this again
7.) when rough cutting balance of current between upper and lower contacts
8.) when finishing machining voltage Aj vs. measured


I can measure 1, probably 2, and maybe 4. Im not sure how to measure the rest.

Does anyone do these voltage checks themsleves and know how to carry it out correctly?

I also notice that if I go to INFO/INPUTS the value there for 'Current' always reads [0.0]

On my PA/SA board there is a machining voltage cable connected there, but on the connector above that labeled current there is not a cable connected there. I dont know what to connect there because there's no obvious other side.. maybe its just there for ct techs to plug in and measure something? will you check your 510 to see if theres a current cable or if you ever see anything other than [0.0] under info/inputs?
 
I got it fixed. It was all the siemens relays 3TK2040-7BB4 4NC. Also there is one of ten that is a 3TK p/n and looks the same but is 2NO 2NC. They all were gummed up presumably with oily shop air, and also the contacts had various types of damage on them, but all were blackened. Some had pits and weld looking marks. You have to turn on the coil on a bench and check the contacts all have less than 1 ohm resistance. after cleaning all mine were dead shorts. before some had 6 to 100 ohm, some almost no conductivity Mohms..

I dont know if cleaning can make them last as long as a new relay, probably there is some arcing protection built into the contacts geometry and those wear down over time so this might not be the fix forever you might need to buy new ones.

I tore down the relays and cleaned the lower contacts portions with 1:1 lime away to water in an ultrasonic bath for 20min ea and scotch brited the contacts on the lowest side then put them back in the bath for a while.

I tested all the relays and all tested good like .2ohm all contacts. so I put those back in and what do you know my servo works great, and i'm cutting 6 to 7 times faster than before with stable servoing.

robofil relays, big problem.

IMG-1593.jpg
 
You mentioned you could not get your nozzles sealed? Is the part not uniform thickness? If it is and the upper head is limited on Z depth (ran 310 and 290 models, not 510) You can make a custom extended nozzle easy enough. We used delrin I think, just thread the end, not sure of thread, think we just checked an existing store bought model for thread dimensions, then leave 1-2-3" sticking out, turn that down to whatever you need 3/4" od or so. The big thing is getting the threaded end with a nice taper into your drilled thru hole.
 
You mentioned you could not get your nozzles sealed? Is the part not uniform thickness? If it is and the upper head is limited on Z depth (ran 310 and 290 models, not 510) You can make a custom extended nozzle easy enough. We used delrin I think, just thread the end, not sure of thread, think we just checked an existing store bought model for thread dimensions, then leave 1-2-3" sticking out, turn that down to whatever you need 3/4" od or so. The big thing is getting the threaded end with a nice taper into your drilled thru hole.

Hey thanks for this suggestion Mike. I had considered making some custom nozzles. The issue with the parts I've been running is that they're different heights and also that the nozzle hangs over an edge or hangs over a hole a lot of the time. My tooling is 3r, like a 3r rail vise for example and the rail is like 1.5" thick or something close. So, if you wanted to cut a 1" thick plate then you cannot seal the nozzle because the head will hit the 3r rail. I think your suggestion about making some nozzles would get around this issue. I'll look into doing it. The reason I didnt do it yet is because the standard nozzle is 'adjustable' and it has some holes around the perimeter for reasons that I dont know. I was worried to break something if I chose too simple of a geometry.
 
Hey thanks for this suggestion Mike. I had considered making some custom nozzles. The issue with the parts I've been running is that they're different heights and also that the nozzle hangs over an edge or hangs over a hole a lot of the time. My tooling is 3r, like a 3r rail vise for example and the rail is like 1.5" thick or something close. So, if you wanted to cut a 1" thick plate then you cannot seal the nozzle because the head will hit the 3r rail. I think your suggestion about making some nozzles would get around this issue. I'll look into doing it. The reason I didnt do it yet is because the standard nozzle is 'adjustable' and it has some holes around the perimeter for reasons that I dont know. I was worried to break something if I chose too simple of a geometry.

Not sure of the holes you speak of, unless you are talking the ones in the interior sides? Those are just 'extra' feed for water IIRC.... Does your machine have auxiliary flushing? It is basically a large loc-line (3/4" ish) that has a mounting block that mounts to the side of the upper head so you can aim an extra 'jet' at the work piece. Should be fairly straight forward to make if your machine is not equipped, just plumb into your high (maybe low, been alot of years) pressure line and feed into the main work area with a pvc or pex type line, then make a block and buy loc-line.

Can't find a linky, but Charmilles made (used to?) an adjustable angle flush cup for the top head. It was basically a ball and socket arrangement that let you adjust angle to match the wire if you were cutting a straight in X or Y taper.

edit: You mean adjustable as in spring loaded? That is normally just for the lower head, and a little tip, if you set the spring so the nozzle is kept down without flushing pressure, it makes it a bit easier to use (your high pressure will overcome the spring pressure *normally*). Also, do you have your height set correctly for the upper head? There is a procedure, outlined in the manual somewhere, when you take a block of known height, and slowly adjust your Z down until you get to around 11 bar with inj set to 4. Then you can use GOH Zxx command to set Z to the top of your part. Also good to run a guide setup before this.
 








 
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