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Need sinker type EDM tutorial?????????!!

fettersp

Aluminum
Joined
Apr 24, 2020
Hello,
My father passed away and he was the one that knew everything about EDM. I only know how to make electrodes and to do basic set up(touch offs and setting zeros). Is there a manual or tutorial that explains these things? currently my parts are coming out a couple grand bigger than there supposed to be and the graphite electrode is wearing out fast. Would the frequency or amperage do anything? This is a sharp f50c edm and I can not find a manual for it.
 
In short, your frequency which I’m guessing is your on and off times won’t have an effect on wear as such. Mainly they effect the cut stability and will effect the speed of cut.

But the amperage will have an effect on your size and wear of electrode. The higher the amperage the bigger the spark gap, so the bigger cavity it will cut.

Also a simple rule of thumb is the more amps, the less the wear.

Luckily with manual machines, you can get by with the sound of the machine to fine tune. So if you know what it should sound like when it’s stable, you’ll figure something out.

Have you sussed out the servo motion settings yet?
 
Is the servo motion the Vertical motion of the machine as it is operating? If so I know a little bit and been playing with some of the knobs but I do not know what some knobs do due to not knowing what the pictures under the knob mean. If I post a picture would you be able to tell me what they mean? Also would I lower my amperage to get more precise cuts but by doing this I will risk the electrode wearing out faster?
 
Yes the servo is the up and down, and yer a good photo of the whole controller will be helpful, I’ll have a go working out what might control what. I’m sure some other folks will give their best guesses.

It’s difficult as most controllers have their own format for settings via the knobs.
 
Here is a picture of the controller.
Also just to make sure higher amps = cuts bigger than supposed to be/ less wear on electrode
-----------------------lower amps = more precise cuts / more wear on electrode

20200424_155613.jpg
 
Yes to your comment above and I suppose the top left (TL) is on time. And BL is off time, where the middle bottom is the amps. I reckon the time knob controls the length of each servo cycle. Second in from TR is I guess the servo force downwards and the top right is the servo force backwards. The others, im less then sure so I won’t confuse things.

Do you have the settings tables for off and on times and amps? That may help fill in some blanks.

My next bit of advice is to think of the generator as an equation. Set the known settings for a particular power setting and set the Remaining knobs in the middle.

Then set a zero in fresh air. And turn on the generator.

In order to understand what each knob does, adjust the knobs to create a servo motion up and down that servos down to the exact same point in fresh air. This would show an equal sided formula. Then adjust the knobs that backs of the downward force. And notice the servo stopping shallower and shallower, then reverse that knob to see the servo stop lower each cycle. Once you can Suss that out, you can create a simple stable condition for cutting downwards.

I used to use this method on a hurco 900, especially using low power settings, where it can be very fine between a good spark and arcing out.

I don’t want to teach how to suck eggs, but you need a stable cut in order to stop burning up and over sparking. Which if your using the right power settings with the correctly machined spark gaps, the cut stability is most likely the issue.
 
Is the servo motion the Vertical motion of the machine as it is operating? If so I know a little bit and been playing with some of the knobs but I do not know what some knobs do due to not knowing what the pictures under the knob mean. If I post a picture would you be able to tell me what they mean? Also would I lower my amperage to get more precise cuts but by doing this I will risk the electrode wearing out faster?

Contact Poco Graphite they offer a free EDM Class that will be very helpful to you. Poco.com
 
Do you know if it is an online course? I would not have the time to be away from the shop as I am still catching up on orders
 
I do not have a settings table that I am aware of.
I have gotten a little better at understanding what some of the knobs do but not to where I want to be. I am currently edming a part right now.
 
Those settings tables will really be essential in setting a benchmark for a stable cut. Unless you’ve got a perfect ear for it, it’ll be hard getting a stable cut, therefore making many problems you’ve described present.
 
Can you answer a few questions.
1) What work piece material are you machining?
2) Electrode material?
3) Size or the EDM surface LxWxD?
4) Do you have an orbiting unit on your machine?
 
Can you answer a few questions.
1) What work piece material are you machining?
2) Electrode material?
3) Size or the EDM surface LxWxD?
4) Do you have an orbiting unit on your machine?



1.Right now I am trying to edm hardened H-13 that need a doughnut shaped cavity 3.25 inches deep. the part is 5 inches in diameter and about 6 inches long.
2. My electrode is graphite.
3. not quite sure but I would say about 5x4x2 feet
4. I don't quite know what an orbiting unit is but I have a roughing and finishing electrode.
 
what do the knobs on the top left and bottom left do exactly?(the knobs with the square waves on them).
someone said on and off time but idk what exactly that means.
 
Yes I put my money on them being the on and off time. On time being the upper. Both expressed in milli seconds. They are they control of the wave form that is generated by the generator. This is different from the wave form that controls servo motion.

The on and off time is a big influence on that all important stability. If you don’t have good stability you will create many issues that result in under and over sized cutting. Also arcing and burning. And electrode wear rate. Like you have described.

The setting sheets are crucial in setting the parameters.
 
yes they are the on and off times. I set the on to 400 and the off to 12. The wear on the electrode is minimal now.
Since this is a roughing electrode is this fine? and to finish I would change electrodes and lower the on time for a more accurate cut?

Is there a way to get the setting sheet for a sharp f50c? or am I just ganna have to learn the hard way?
 
yes they are the on and off times. I set the on to 400 and the off to 12. The wear on the electrode is minimal now.
Since this is a roughing electrode is this fine? and to finish I would change electrodes and lower the on time for a more accurate cut?

Is there a way to get the setting sheet for a sharp f50c? or am I just ganna have to learn the hard way?
Sharp is a large Japanese machine tool company. Have you tried getting a machine manual from them? The manual is the best source for Machine burn settings. Most shops develop in-house settings. But the 80-90 era machines are going to use very similar settings, once you figure out the knob hieroglyphics. You can use a worn finishing electrode as a rougher.

Sent from my SM-G975U using Tapatalk
 
I suspect the far right knobs are pulse flushing. Upper is work off, lower is time down. Pulse flushing is like a plunger when you don't have good flushing through the electrode. Others have commented on the other knobs.
 
I run a machine with an identical control cabinet so I may be able to off some help in naming things. Starting from the left top and bottom you have:

off time, on time; sensitivity, head down time; no name on ours, amperage; voltage gap, don’t know; head up distance/time, not 100% sure. That switch on the far right controls whether it’s a plunge or peck burn

I was taught you want to see 200v on the left meter when it isn’t burning and 100v when it is. Without having my machine in front of me I believe it’s the bottom right knob. Also the stab meter is STABILITY and red is good, if you’re seeing burns very low on the bar you’re having flushing problems or your settings are out of whack.

Outside of the first third of the manual the rest of the book consists of charts and lists of burn conditions showing surface finish, MRR and electrode wear etc.

If your machine is anything like ours all flushing will be controlled on the left hand side with a series of 4 or 5 knobs and a lever that diverts the tank fill, see the picture for which are pulse and vacuum etc.
 








 
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