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View Full Version : Calling folks who know wire EDM......



J Tiers
02-17-2015, 08:43 PM
I started a thread in the CNC area (thinking that was the best) but if anyone who does not look there knows wire EDM, and has ideas on fixing a Makino EC 7050 that breaks wire above 3A, I'd appreciate ideas.

Thread here:

http://bbs.homeshopmachinist.net/threads/66065-Slightly-OT-repair-of-a-Makino-wire-EDM-that-eats-wire-need-ideas?p=968175#post968175

oldtiffie
02-17-2015, 09:22 PM
I've never seen EDM and all I know about it (nearly zero) is what I've read about it.

I did Google it to see what may be on offer and here it is - hope it helps:

http://en.wikipedia.org/wiki/Electrical_discharge_machining

https://www.google.com.au/?gws_rd=ssl#q=edm+machining&revid=1257603050

outback
02-18-2015, 07:19 AM
With wire EDM it is mostly about flushing, keeping the wire cool and the cutting area as free of grit as possible. There is also feed rates and wire speed. Sometimes the wire itself makes a difference.

Running a wire EDM slowly is relatively easy. But running at competitive speeds is more difficult. Lots of
trial and error. Wire EDMs are a rather special animal total unlike other cutting machines.

I have a Hansvedt DS-2 wire EDM I would like to sell if anyone is interested. All setup to run on a rotary phase converter from home power.
Jim

J Tiers
02-18-2015, 08:19 AM
With wire EDM it is mostly about flushing, keeping the wire cool and the cutting area as free of grit as possible. There is also feed rates and wire speed. Sometimes the wire itself makes a difference.


That's where I am getting to with the unit. Dirty water, or poor flushing. They claim to have been running the flushing the same way and having it cut at intended rate, and then more recently had the max rate they can use decrease gradually. That could be filtering (dirty water) also.

George Bulliss
02-18-2015, 08:26 AM
Will reply here so you don't have to jump between forums.

Agree that the water and flush should be checked. The flush cups do wear out. The water stream may look the same but it doesn't take much to start breaking the wire. Wonder if a water conditioner place could check the water to see if the resin filters are doing their thing?

Also agree that wire can make a big difference and some of the discount spools just wouldn't work at all for us.

outback
02-18-2015, 09:18 AM
Water needs to be filtered and de-ionized. Those water filters are large and expensive to replace. In a pinch the filters can be cleaned. There is a bag of resin to de-ionize the water and those need to be changed as needed.

The flush nozzles need to be as close to the workpiece as possible both upper and lower. There is also
water pressure. I would increase water pressure by listening to the spark. Increase the water pressure until the sparks sounds real steady and even

MrFluffy
02-18-2015, 10:56 AM
The resin needs replacing when it can't get the resistivity of the water down enough but the machine should have a monitor for that somewhere surely? Same as pressures, mine has two flowmeters I can set the flow on at the machine stand itself.
One thing nobody has said yet is to go over the table connections minutely, if there's any resistance on the power leads or they come loose at all they can erode the connection away compounding issues, and its progressive from what I have learned and mine were duly knackered when I first checked. On my sodick I picked up a bunch more speed and less wire breakage when I cleaned all the inter table connections up fastidiously too, as on that the table is different segments with a big copper corner segment bonding them together electrically.
The other obvious thing is the carbide contacts, they have to be indexed and reset on my machine as a service thing and I cant see as a different marquee would be any different.

I'm with george on the flushing, exactly how important it is took a while to get through to me, but he said that to me too, and it cured a lot of my earlier wire breakages. I wonder if the efficiency of the pump itself might be dropping with wear ditto the filters are hour based service pieces, have they been changed out?
Ditto switching wire, I started off with a spool of hard brass I got off ebay that was a nightmare, but now I'm running coated zinc and its night and day for breakages, I got another spool of all hard brass and its much better, so I switched back to the original and broke it lots so I've given that original roll to someone local to use for something else.

A man of your calibre could and probably has already scoped the output at the machine end and at the wire and see if its loosing any of the edm pulse to eliminate the connections and relays though.

J Tiers
02-18-2015, 01:50 PM
Wires and connections were apparently renewed recently. I didn't scope it, but the guy who did reported no issues visible. I plan to do it, had little time the last time I was over there.

Contacts etc were renewed at large expense pretty recently, maybe 2 months, I am told.

Spark is already very even and good sound, regular bacon frying with no pops or dropouts audible.

They claim the flushing is good, but I'm not on-board with that the more I think about it. He was cutting an HSS form tool when I watched it, and the flow looked unimpressive to me. I thought it could be better, the cut is small (0.25mm wire) and deep, needs pressure to get it to flow through there well.

I'm going to have to think about how to politely tell him that he needs to check some basics.... when he is the wire EDM guy, and I am a hack manual machinist who "don't know EDM wire from pack thread".