Wire people esp. Fanuc

[Matt Berube at Ferron Mold]

Hey,

 

We've had intermittent problems getting a good edge find or verticality check with our Fanuc.

 

A few weeks ago we decided to replace the guides which helped out immediately.

 

Today the wire operator is having all kinds of trouble again and I'm out of ideas.

 

We have switched to a different spool of wire which seemed to help a little but not really...

 

The workpiece is demagnetized.

 

The "electrode pins" are clean and not worn.

 

We have a couple ground cables that were damaged a while back (new ones on the way).

 

Anybody have ideas for what could be affecting the edge find accuracy ?

 

Would bad ground wires cause this ?

 

How about the other smaller wires that attach to the lower head ?

 

[Guest]

are you edge finding under water.

is wire tension set to 1700

is surface machined or ground (use india stone on side)

is the water clean.

when was the last time you checked your wire tension with a meter.

when was the last time you checked the verticality

of the wire.

is the part setting perpidicular to the table.

 

just a few thoughts.

[Guest CNC Apps Guy 1]

I'd call Methods in Mass @ (978)443.5388 and talk to an AE.

 

But that's just me 'cuz I don;t know $#!+ about EDM. I took a 16 week course once a LONG time ago

 

HTH

[Guest]

matt, my first guess is that the surface you are checking is not square to the wire.you may have to manually square the wire to the part.

[Guest]

matt, another thing.when was the last time you tore the upper and lower heads down and cleaned them and replaced the lower roller bearings.

[edmBosto]

Matt,

Yeah what Del said.

Seriously though how is the repeatability as in tenths when picking up the edge?

I'll show this to my wire guru tomorrow as maybe he'll have a suggestion also.

Did the last job burn square to the side or top?

Maybe there's a burr on the steel causing some shavings.

[Matt Berube at Ferron Mold]

under water...yes

tension...1700

Is surf machined or ground... yes, it is a knockout pin laying down and he was trying to pick up central to the dia (finish ground).

water is visually crystal clear

tension checked today.

verticality... was trying to check today with the official Fanuc block but kept alarming out due to inaccurate edge pickups. Finally he got a slightly better result a few minutes ago but not perfect.

The pin is accurately held in a vee block and is inline with the X axis.

 

If you watch the numbers while it is edge finding you can see that is is hitting all different values instead of being consistent...

 

It is behaving exactly like when the piece is magnetized and there is fine metallic dust clinging to it but I am certain it is clean and demagged. This behavior was happening on the pin as well as the vert fixture.

[Matt Berube at Ferron Mold]

lower bearings new today.

 

cleaned entire wirepath (except pinch rollers and lower tube) today.

 

I was thinking of having him check out the pinch rollers tomorrow.

 

I am not sure how much variation he had exactly but it was bad enough that he could see it was off DURING the edge find while the machine was still measuring.

 

There have been no accuracy or squareness issues with the machine. Last part was fine.

 

I just remembered something from class at Methods too...

I will have him take the fixture off the table and stone it. The fixture we are holding the vert gage in has been on the table in the same spot for quite a while... I wonder if there is resistance between the fixture and the table...

[Guest]

matt, that makes it toughwhen are are only hitting on such a small surface if i understand you correctly.i have that problem also sometimes. i usually just increase my tension to about 1900 kg.i am assuming also that you can't get the upper and lower head close to the pin.

[Matt Berube at Ferron Mold]

The nozzles are within 1.5 inches from the pin. We have had no problems with this type of pickup before. Usually in my experience the pickup is better because of the reduced surface area.

[ToolMan184]

quote:

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Would bad ground wires cause this ?

---

I would say yes. i had kind of the same a couple years ago and it turned out to be bad ground cables. Almost drove me to . Also the fixture should be taken off and cleaned regularly. You get build up and the current cant flow as well, like a car battery, if the terminals get corroded cleaning the battery is the thing to do.

 

I never knew how important cleaning (weekly) and maint. on a wire machine was. The first year I had one I learned alot the hard way. Never again.

[edmBosto]

Matt,

I talked it over with my buddy and he thinks;

quote:

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I will have him take the fixture off the table and stone it

---

It's seems most likely a conductivity issue and cleaning the fixture is a great starting place.

You seem to be on the right track though.

Let us know how you make out.

[gavetta]

From my experiences as a wire edm operator from a few years ago, conductivity is a big factor as is wire tension. I agree completely with Toolman, Bosto and del. I can also tell you I had a machine that had bad ground cables and that created alot of headaches. My best advice would be get new cables (you said you had them on the way), clean all contact surfaces on everything, make sure your DI water is clean and good(when was the last time you had the bedding or bottles changed). Conducutivity of the work piece and non-conductivity of the water is majorly important. Picking up on a pin is tricky if you can't get close but you should be ok with the higher wire tension. Just my .02

[Matt Berube at Ferron Mold]

Thanks Guys.

 

I'll try to give an update after the wires are changed.

 

For now he finally got some numbers he *sort-of* trusts and we're running.

[88Matt]

The ground side of the circuit is very important, i.e.: cables, wires, mated surfaces, bolt threads... Also, are you using tap water or RO/DI water?

[Matt Berube at Ferron Mold]

quote:

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RO/DI

---

 

Not sure what that means but we add tap water as necessary and then the machine circulates through the resin bottle until the "resistivity" comes back to normal.

[ToolMan184]

Matt,

 

A little trick we do. We have a spare DI bottle we have hooked up to the tap water on a timer. When we add to the machine it goes through the DI bottle. Yeah, it kills the spare DI bottle quicker but its better than killing the water in the machine.

[Guest CNC Apps Guy 1]

RO = Reverse Osmosis Water

DI = Deionized Water

 

That much I DO know.

[Matt Berube at Ferron Mold]

I spoke with the operator yesterday and it seems that replacing cables and cleaning contacts made all the difference. Problem solved.

 

Now today we got an alarm for a chiller flow blockage. Hopefully he can flush it out without any disasters...

 

Thanks for the help !

[edmBosto]

Glad to learn of the success

[ToolMan184]

Matt, Make sure you clean your tank at least every 6 months or so. There is alot of sludge that can build up in the bottom. You may even have to do it every 3 months.