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Wire EDM general performance in real terms...

I scrapped a surface grinder the same time I scrapped the sinker (and 3 other machines)

Thought I would start a product that required surface grinding.

I'd forgotten I f'ing hate grinding. Surface grinding was the at the center of maybe one of my more spectacular f'ups. In 1979 back in the UK., still remember like it was yesterday.
Of course letting a young kid loose on a surface grinder and not even asking him whether he'd used one before
What possibly could go wrong? (quite a lot actually)

I can actually grind very well these days, just choose not to.
Probably some thing to do with the fact that grinders in general are grotesquely misshapen:eek: and objectionable humans, and I didn't want to become one:)
Well, I cannot agree.
The surface grinder brought me to a level of precision, I had never imagined.
Hey, and it does a really nice job on my fingernails when I think they need dressing....
 
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One of the things I love using our wire for is making multiple parts. I load in a 12.000 bar and when I come in at 0600 I have 8 blocks cut out that only need clearance holes and counterbores put in them. Or it works while I'm working on something else. Doesn't need to be fast but I know I'm gonna have a net finished part for that operation when it gets done.
 
Hi again snowshooze:
OK, you are going ahead or so it appears.
Congratulations.
Your next challenge is to figure out where to spend your pennies.
You can choose new or used.
You can choose high end, middle of the road or cheapo.
You can choose big or medium or little.

All of these choices have consequences.
Let me tell you of my experience:

I bought a used Sodick A320 from a reputable dealer. (EDM Network in Illinois)
It was fully reconditioned when I bought it and was a 1996 model that I got in 2008.
I ran it for 4 years and then upgraded to a brand new Chmer from the same dealer in 2011.
I paid abouut 97K (Canadian dollars) for it in 2011 and another 30K for the rotary.

I did so because the old Sodick kept breaking down...I had board failures and computer failures, pump failures and wire drive failures etc etc.
Every time it broke down it was a major pain in the ass to get it running again and all my wire customers were pissed at the delays.

It was not the dealer's fault in any way...it was an old high miler when I bought it and I knew that but took the chance.
I paid about four times the price for what was being offered on EBay at the time for the same brand, model and vintage, but in my case I had dealer support, so when it crapped out I had somewhere to turn, and I have to say, the support was excellent.

My new Chmer is a Chevy...a solid mid range performer that is capable of 2 tenths routinely and a tenth with care.
It is a very heavily built machine, that is now older than the Sodick was when I got it, but I have had almost zero problems with it.
Some teething troubles when it was new... all resolved promptly by EDM Network over the phone.
I've had a technician in one single time and it cost me about 3 grand to have him fly in from Illinois.
A power supply had crapped out and taken out a board.

I had to replace all the air hoses at the ten year mark...they were all decomposing and blowing out at inconvenient times. (crappy hose material)
It took a solid day.
I've had the chiller drop out occasionally but a phone call and some instructions fixed that.
Ditto for the rotary axis servo driver.
A few other minor things of a similar nature...all easily fixed and without spending a lot.

As I said, I run the machine about 20 hours a week and I wouldn't be without one for the work I typically do.
Much of it is not "wire work", it is merely the most convenient way for me to do the job since I already have the toy.

So my experience with this mid range Taiwanese brand has been very good indeed, especially when I contrast it with the experience of a buddy who bought top of the line Swiss.
He could do better than me when his machine was new...half a tenth instead of a tenth and 8 microinch instead of 16 microinch.
But when he blew a monitor it was...wait for it....8 Grand!
I crapped my panties hearing that.
To add insult to injury the machine was down for MONTHS.

So for your circumstances...new has some attraction in that you have a fall back position on the day when the monitor stays dark as you push the green button.
In Alaska, I wouldn't be without that security unless you're a diagnostic whizzo and have all the time in the world to source the bits and fix the machine.

The other thing to be very aware of...DON'T BUY AN ORPHAN.
Some brands were never very popular and some models were dogs.
Don't get one of those...you will hate the whole experience.

Another thing if you go used...how pretty it looks has ZERO bearing on whether it will work reliably.
Wires don't get beat up like VMC's or lathes do...they almost all still look pretty, decades after they are ready to crap out.
Two things tend to fail:
1) The electronics
2) The auxiliary systems like flush pumps and wire transport system.

The electronics is often the bigger worry...if you can't get the boards or the board components anymore your machine becomes a boat anchor.
Mechanical shit you can fix.

So that's it...good luck with your decision and happy burning.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
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Hi again snowshooze:
OK, you are going ahead or so it appears.
Congratulations.
Your next challenge is to figure out where to spend your pennies.
You can choose new or used.
You can choose high end, middle of the road or cheapo.
You can choose big or medium or little.

All of these choices have consequences.
Let me tell you of my experience:

I bought a used Sodick A320 from a reputable dealer. (EDM Network in Illinois)
It was fully reconditioned when I bought it and was a 1996 model that I got in 2008.
I ran it for 4 years and then upgraded to a brand new Chmer from the same dealer in 2011.
I paid abouut 97K (Canadian dollars) for it in 2011 and another 30K for the rotary.

I did so because the old Sodick kept breaking down...I had board failures and computer failures, pump failures and wire drive failures etc etc.
Every time it broke down it was a major pain in the ass to get it running again and all my wire customers were pissed at the delays.

It was not the dealer's fault in any way...it was an old high miler when I bought it and I knew that but took the chance.
I paid about four times the price for what was being offered on EBay at the time for the same brand, model and vintage, but in my case I had dealer support, so when it crapped out I had somewhere to turn, and I have to say, the support was excellent.

My new Chmer is a Chevy...a solid mid range performer that is capable of 2 tenths routinely and a tenth with care.
It is a very heavily built machine, that is now older than the Sodick was when I got it, but I have had almost zero problems with it.
Some teething troubles when it was new... all resolved promptly by EDM Network over the phone.
I've had a technician in one single time and it cost me about 3 grand to have him fly in from Illinois.
A power supply had crapped out and taken out a board.

I had to replace all the air hoses at the ten year mark...they were all decomposing and blowing out at inconvenient times. (crappy hose material)
It took a solid day.
I've had the chiller drop out occasionally but a phone call and some instructions fixed that.
Ditto for the rotary axis servo driver.
A few other minor things of a similar nature...all easily fixed and without spending a lot.

As I said, I run the machine about 20 hours a week and I wouldn't be without one for the work I typically do.
Much of it is not "wire work", it is merely the most convenient way for me to do the job since I already have the toy.

So my experience with this mid range Taiwanese brand has been very good indeed, especially when I contrast it with the experience of a buddy who bought top of the line Swiss.
He could do better than me when his machine was new...half a tenth instead of a tenth and 8 microinch instead of 16 microinch.
But when he blew a monitor it was...wait for it....8 Grand!
I crapped my panties hearing that.
To add insult to injury the machine was down for MONTHS.

So for your circumstances...new has some attraction in that you have a fall back position on the day when the monitor stays dark as you push the green button.
In Alaska, I wouldn't be without that security unless you're a diagnostic whizzo and have all the time in the world to source the bits and fix the machine.

The other thing to be very aware of...DON'T BUY AN ORPHAN.
Some brands were never very popular and some models were dogs.
Don't get one of those...you will hate the whole experience.

Another thing if you go used...how pretty it looks has ZERO bearing on whether it will work reliably.
Wires don't get beat up like VMC's or lathes do...they almost all still look pretty, decades after they are ready to crap out.
Two things tend to fail:
1) The electronics
2) The auxiliary systems like flush pumps and wire transport system.

The electronics is often the bigger worry...if you can't get the boards or the board components anymore your machine becomes a boat anchor.
Mechanical shit you can fix.

So that's it...good luck with your decision and happy burning.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
Marcus;
Sage advice.
All my CNCs' save one were breakdown rigs. I fixed them and did real good.
Boards, encoders, bearings...
But, ya know, that isn't really my gig. I am slow at it.
But better than the one Fadal guy I flew up...
He was trying to get me to purchase a full complement of amps....
I told him no man. It's in the safety circuit. In the pendulum. Right about here...
It was a blown card for the hand-held MPG.
There are absolutely NO CNC repair guys here.
I am one of just a hand-full of shops in the game.
So, I was looking at that Fanuc... solid brand I know...
But, soon as word get's out... I am going to need reliability.
Many thanks!
Mark
 
Hi again snowshooze:
OK, you are going ahead or so it appears.
Congratulations.
Your next challenge is to figure out where to spend your pennies.
You can choose new or used.
You can choose high end, middle of the road or cheapo.
You can choose big or medium or little.

All of these choices have consequences.
Let me tell you of my experience:

I bought a used Sodick A320 from a reputable dealer. (EDM Network in Illinois)
It was fully reconditioned when I bought it and was a 1996 model that I got in 2008.
I ran it for 4 years and then upgraded to a brand new Chmer from the same dealer in 2011.
I paid abouut 97K (Canadian dollars) for it in 2011 and another 30K for the rotary.

I did so because the old Sodick kept breaking down...I had board failures and computer failures, pump failures and wire drive failures etc etc.
Every time it broke down it was a major pain in the ass to get it running again and all my wire customers were pissed at the delays.

It was not the dealer's fault in any way...it was an old high miler when I bought it and I knew that but took the chance.
I paid about four times the price for what was being offered on EBay at the time for the same brand, model and vintage, but in my case I had dealer support, so when it crapped out I had somewhere to turn, and I have to say, the support was excellent.

My new Chmer is a Chevy...a solid mid range performer that is capable of 2 tenths routinely and a tenth with care.
It is a very heavily built machine, that is now older than the Sodick was when I got it, but I have had almost zero problems with it.
Some teething troubles when it was new... all resolved promptly by EDM Network over the phone.
I've had a technician in one single time and it cost me about 3 grand to have him fly in from Illinois.
A power supply had crapped out and taken out a board.

I had to replace all the air hoses at the ten year mark...they were all decomposing and blowing out at inconvenient times. (crappy hose material)
It took a solid day.
I've had the chiller drop out occasionally but a phone call and some instructions fixed that.
Ditto for the rotary axis servo driver.
A few other minor things of a similar nature...all easily fixed and without spending a lot.

As I said, I run the machine about 20 hours a week and I wouldn't be without one for the work I typically do.
Much of it is not "wire work", it is merely the most convenient way for me to do the job since I already have the toy.

So my experience with this mid range Taiwanese brand has been very good indeed, especially when I contrast it with the experience of a buddy who bought top of the line Swiss.
He could do better than me when his machine was new...half a tenth instead of a tenth and 8 microinch instead of 16 microinch.
But when he blew a monitor it was...wait for it....8 Grand!
I crapped my panties hearing that.
To add insult to injury the machine was down for MONTHS.

So for your circumstances...new has some attraction in that you have a fall back position on the day when the monitor stays dark as you push the green button.
In Alaska, I wouldn't be without that security unless you're a diagnostic whizzo and have all the time in the world to source the bits and fix the machine.

The other thing to be very aware of...DON'T BUY AN ORPHAN.
Some brands were never very popular and some models were dogs.
Don't get one of those...you will hate the whole experience.

Another thing if you go used...how pretty it looks has ZERO bearing on whether it will work reliably.
Wires don't get beat up like VMC's or lathes do...they almost all still look pretty, decades after they are ready to crap out.
Two things tend to fail:
1) The electronics
2) The auxiliary systems like flush pumps and wire transport system.

The electronics is often the bigger worry...if you can't get the boards or the board components anymore your machine becomes a boat anchor.
Mechanical shit you can fix.

So that's it...good luck with your decision and happy burning.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
Hey, let's start with the big, medium, little.
What is big, what is little, and what are the trade-offs?
If you have time...
Oh, and if I took the gamble, are the Fanuc Wires ok?
Again,
My many thanks!
Mark
 
Oh, and if I took the gamble, are the Fanuc Wires ok?
I run a 400 series Fanuc Robocut. Solid machine. I think it's a mid-2000s/2010s machine (The school bought it used in 2014? before I started). I don't have any other machine to compare it to - but the amount of hair-tearing that I experience due to it is minimal (compared to lecturing students who did not fully engage Hi gear on the Bridgeports -_- )
 
I run a 400 series Fanuc Robocut. Solid machine. I think it's a mid-2000s/2010s machine (The school bought it used in 2014? before I started). I don't have any other machine to compare it to - but the amount of hair-tearing that I experience due to it is minimal (compared to lecturing students who did not fully engage Hi gear on the Bridgeports -_- )
I am looking at the ebay one.
Thanks!!!
Mark
 
snowshooze,

I got into the wire edm business in ~2003. It didn't take me long to realize that I was having to explain how the process worked to many of the potential customers that either came to my business, or called me. So... ~20 years ago, I created "FAQ" pages on my web site, so I could just point people to various pages of information that they could read (and I didn't have to repeat the same info to everyone that dropped by or called me). I am no longer in this business, however....

Possibly this page might be of use:

PM

======================

WIRE EDM FAQ page:

What kind of material can be cut?

Any material that conducts electricity, regardless of hardness.
Aluminum, magnesium, copper, brass, titanium, steel of any type/alloy/hardness, carbide, gold, silver, platinum, graphite, and many others.

How fast is the wire edm cutting process?
Typically, the wire edm process is slower in material removal than other "conventional" machining processes. However, this does not necessarily mean that completing a part is slow.
There are times when even though a part can be made using conventional machining methods, it can be made faster with wire edm. An example of this might be when a thin, delicate part has to be made from a large block of material due to its configuration -- conventional machining would require ALL the excess material be machined away, whereas wire edm might be used to drop out all the excess material with one or two simple cuts.
Direct comparison between conventional machining methods and wire edm can not be "generalized" however, and must be looked at on a part by part basis.

What determines cutting speed?
Cutting speed is primarily determined by...
1) Size of wire used
2) Thickness of the part
3) Density of the material
4) Profile/shape being cut

Also: wire edm machines are typically described as being capable of “xx” number of square inches of cutting/hour (or mm/minute, etc.). In other words: a manufacturer may say something like — their machine will cut steel at 20 square inches/hour. This example would mean that the machine could make a 20” long cut (along whatever path the part profile dictates) in 1” thick steel plate in one hour. BE AWARE: this does not scale up OR down linearly. The “sweet spot” for maximum “square inches per hour” (in my experience) is typically in 1” to 2” thick material (the material cutting rate is also dependent on excellent flushing conditions, which can be difficult to accomplished unless the plate/blank is very flat and parallel so that the “flushing nozzles” can be in contact with the material top and bottom -- or at the very least: very very close to the material). BUT, here is the caveat: material cutting rate (in square inches or millimeters/hour) goes DOWN when the material is thin OR when it is thick. .250” thick material will not cut at 4 times the speed of 1” thick material. And 6” thick material will not cut at one-third the speed of 2” thick material. As the material thickness gets further and further away from that 1”-2” thickness, “material cutting rate” in square inches/hour goes down. (in my experience)

What is the range of wire sizes used?
Wire size ranges from .0008" (20 micron) to .013". Most wire edm machines are designed to run .006" to .010" diameter wire. Machines using .0008" wire are very specialized, and typically have a very small "work area" designed primarily for tiny parts used in the medical or electronics industry.

What determines the size wire used?
Typically, wire size is determined by the smallest inside radius required on the part. For example; a part might contain a square hole with a maximum radius of .003" in the corners. In this case, the choice would probably be .004" wire. Generally speaking, it's advantageous to use the largest wire possible as that will cut the fastest (large wire can carry more power proportionally to the amount of material being cut away). There are occasionally situations where using smaller wire is beneficial though... primarily when cutting thin material with intricate/fine details. Machines exist that actually hold 2 spools of wire of a different size, allowing faster cutting on parts of the profile with no tight inside radii, and then the machine can change to a smaller wires size to “finish” a required small inside radius that the larger wire could not complete. These machines are typically very expensive.

How thick a part can be cut?
Most wire edm machines have a "Z" capacity in the 10" to 12" range. Larger capacity machines may be able to handle parts as thick as 16" or more, and very specialized machines have been built that will cut parts 24" thick or more. On the opposite end of the scale, ultra-fine wire machines using 20 micron wire may only have a Z capacity of 2 or 3 inches.

How thin a part can be cut?
Cutting .001" or even .0005" thick material is simple. When cutting very thin parts, the material is usually "captured" between two sacrificial plates, and the entire "stack" is cut as a unit. Needless to say, if cutting thin parts, many blanks can be “stacked” — in other words: 1000 pieces of .001” thick material could be “captured” between say… .250” thick plates (making the entire stack 1.5” thick), so cutting “once” would yield 1000 parts.

How accurate is the wire edm cutting process?
Typically more accurate than any conventional machining process.
Wire edm has one distinct advantage over any form of conventional machining -- there are no cutting forces. The wire never contacts the workpiece, so the "path" that the wire takes through the part is not influenced by any mechanical forces. Additionally, wire cutting is typically done submerged in very pure, temperature-controlled water, so dimensional changes due to temperature are minimized or completely eliminated. An extra benefit to having no cutting forces is that parts can be held very lightly, which minimizes or completely eliminates the distortion due to clamping forces seen in conventional machining methods. Thin/delicate parts can be cut very precisely using wire edm.
In order to achieve very high accuracy though, it is often necessary to make more than "one pass" on a profile.

Why is more than one cut ever required?
Two reasons; greater accuracy and/or finer surface finish (the two go hand-in-hand). When cutting using a "single pass", power settings are usually quite high and consequently the surface finish will have a "glass-beaded" texture to it after cutting. Additionally, two other factors can slightly influence wire position during the first pass of a wire cut -- electromagnetic forces on the wire, and high "flushing pressure" used to continually wash away the eroded material. These forces do not move the wire very much (a few tenths possibly), but this nevertheless affects accuracy (more so in tall parts). In order to achieve greater accuracy, multiple cuts are employed where the "offset" of the wire is reduced (easier to think of it as "spark gap"), and the electrical settings are altered (lower power and different waveform). When very fine finishes are required (Ra10 / 10 micro-inches or better ), as many as 1 to 5 additional "trim passes" can be used after the initial cut. Each pass will have less offset and lower power than the previous one. Whether it's fine finishes or ultra-precise tolerances that are required, multiple passes are the way it's done in wire edm.

What is the biggest limitation of wire edm?
The single biggest limitation of wire edm is that it must be possible to pass the wire by or through the part. The wire is continuous... so it's not possible to cut a "blind" cavity using wire edm.

Can complex shapes be cut?
Yes, within some reasonable limits. Most modern wire edm machines can cut up to 30° taper (or more precisely; the wire can be inclined up to 30°). Some machines can even go up to 45°. Note that since the upper axis on a wire edm machine is typically a "differential" axis (it translates relative to X/Y), a 30° angle is possible up to a certain part thickness, and after that the available angle reduces relative to the height of the part. Obviously if the part itself can be tipped or rotated, any angle is then possible. Using a rotary axis or a dividing head can allow cutting complex/multiple angle cuts. Additionally, the angle of the wire can be continuously changed (X/Y vs. U/V) while cutting, which allows the cutting of complex surfaces. Essentially; if a straight line can be passed along a contour, it can probably be cut by wire edm.

How accurately can you cut a feature on my existing parts?
The key words in that question are "existing parts". Since an existing part is often fixtured on a previously machined surface (or surfaces), the limitation in accuracy is often those already-machined surfaces. If a particular feature is cut via wire edm, that feature will have all the accuracy that the wire edm machine is capable of, but positional accuracy may be dependent on previous work. In a one-off situation, this issue can sometimes be partially negated by "touching off" on all previously machined surfaces and striking the best possible balance of dimensions to achieve positional accuracy. In production however, fixtures may be used that rely on previous machining to mount/clamp parts quickly, and if those parts are not consistent, accuracy may suffer.
Wire edm is really no different than any other form of machining in this regard, except that wire edm machines are typically much more accurate than other types of CNC machines, so small variations in accuracy from part to part become obvious and glaring errors when compared to what is possible in the wire edm machine.
 
I have to make some tool wedges for the turret of my Mori cnc lathe. they have an 8 deg taper on the block and wedge

"If only I had a wire, they'd be so easy to make......"

I guess I'm going old school, vise mounted to a sine plate
 
BUT, here is the caveat: material cutting rate (in square inches or millimeters/hour) goes DOWN when the material is thin OR when it is thick. .250” thick material will not cut at 4 times the speed of 1” thick material. And 6” thick material will not cut at one-third the speed of 2” thick material. As the material thickness gets further and further away from that 1”-2” thickness, “material cutting rate” in square inches/hour goes down. (in my experience)

I didn't know that. I would assumed that material thickness had a direct correlation to travel speed. Thank you!
 
I didn't know that. I would assumed that material thickness had a direct correlation to travel speed. Thank you!
Sometimes but not always...when you talk about something going faster in wire edm it's a matter of a few .010 per minute increase a lot. If you play with the machine you can get better results, but it's not like in a mill where you can get 100s of inches per minute with smaller thickness.

Fastest I ever got was .75 ipm on 1.000 aluminum in a mits mv2400 advance with 12 wire and a jacked up epack...I was ecstatic lolol
 
snowshooze,

I got into the wire edm business in ~2003. It didn't take me long to realize that I was having to explain how the process worked to many of the potential customers that either came to my business, or called me. So... ~20 years ago, I created "FAQ" pages on my web site, so I could just point people to various pages of information that they could read (and I didn't have to repeat the same info to everyone that dropped by or called me). I am no longer in this business, however....

Possibly this page might be of use:

PM

======================

WIRE EDM FAQ page:

What kind of material can be cut?

Any material that conducts electricity, regardless of hardness.
Aluminum, magnesium, copper, brass, titanium, steel of any type/alloy/hardness, carbide, gold, silver, platinum, graphite, and many others.

How fast is the wire edm cutting process?
Typically, the wire edm process is slower in material removal than other "conventional" machining processes. However, this does not necessarily mean that completing a part is slow.
There are times when even though a part can be made using conventional machining methods, it can be made faster with wire edm. An example of this might be when a thin, delicate part has to be made from a large block of material due to its configuration -- conventional machining would require ALL the excess material be machined away, whereas wire edm might be used to drop out all the excess material with one or two simple cuts.
Direct comparison between conventional machining methods and wire edm can not be "generalized" however, and must be looked at on a part by part basis.

What determines cutting speed?
Cutting speed is primarily determined by...
1) Size of wire used
2) Thickness of the part
3) Density of the material
4) Profile/shape being cut

Also: wire edm machines are typically described as being capable of “xx” number of square inches of cutting/hour (or mm/minute, etc.). In other words: a manufacturer may say something like — their machine will cut steel at 20 square inches/hour. This example would mean that the machine could make a 20” long cut (along whatever path the part profile dictates) in 1” thick steel plate in one hour. BE AWARE: this does not scale up OR down linearly. The “sweet spot” for maximum “square inches per hour” (in my experience) is typically in 1” to 2” thick material (the material cutting rate is also dependent on excellent flushing conditions, which can be difficult to accomplished unless the plate/blank is very flat and parallel so that the “flushing nozzles” can be in contact with the material top and bottom -- or at the very least: very very close to the material). BUT, here is the caveat: material cutting rate (in square inches or millimeters/hour) goes DOWN when the material is thin OR when it is thick. .250” thick material will not cut at 4 times the speed of 1” thick material. And 6” thick material will not cut at one-third the speed of 2” thick material. As the material thickness gets further and further away from that 1”-2” thickness, “material cutting rate” in square inches/hour goes down. (in my experience)

What is the range of wire sizes used?
Wire size ranges from .0008" (20 micron) to .013". Most wire edm machines are designed to run .006" to .010" diameter wire. Machines using .0008" wire are very specialized, and typically have a very small "work area" designed primarily for tiny parts used in the medical or electronics industry.

What determines the size wire used?
Typically, wire size is determined by the smallest inside radius required on the part. For example; a part might contain a square hole with a maximum radius of .003" in the corners. In this case, the choice would probably be .004" wire. Generally speaking, it's advantageous to use the largest wire possible as that will cut the fastest (large wire can carry more power proportionally to the amount of material being cut away). There are occasionally situations where using smaller wire is beneficial though... primarily when cutting thin material with intricate/fine details. Machines exist that actually hold 2 spools of wire of a different size, allowing faster cutting on parts of the profile with no tight inside radii, and then the machine can change to a smaller wires size to “finish” a required small inside radius that the larger wire could not complete. These machines are typically very expensive.

How thick a part can be cut?
Most wire edm machines have a "Z" capacity in the 10" to 12" range. Larger capacity machines may be able to handle parts as thick as 16" or more, and very specialized machines have been built that will cut parts 24" thick or more. On the opposite end of the scale, ultra-fine wire machines using 20 micron wire may only have a Z capacity of 2 or 3 inches.

How thin a part can be cut?
Cutting .001" or even .0005" thick material is simple. When cutting very thin parts, the material is usually "captured" between two sacrificial plates, and the entire "stack" is cut as a unit. Needless to say, if cutting thin parts, many blanks can be “stacked” — in other words: 1000 pieces of .001” thick material could be “captured” between say… .250” thick plates (making the entire stack 1.5” thick), so cutting “once” would yield 1000 parts.

How accurate is the wire edm cutting process?
Typically more accurate than any conventional machining process.
Wire edm has one distinct advantage over any form of conventional machining -- there are no cutting forces. The wire never contacts the workpiece, so the "path" that the wire takes through the part is not influenced by any mechanical forces. Additionally, wire cutting is typically done submerged in very pure, temperature-controlled water, so dimensional changes due to temperature are minimized or completely eliminated. An extra benefit to having no cutting forces is that parts can be held very lightly, which minimizes or completely eliminates the distortion due to clamping forces seen in conventional machining methods. Thin/delicate parts can be cut very precisely using wire edm.
In order to achieve very high accuracy though, it is often necessary to make more than "one pass" on a profile.

Why is more than one cut ever required?
Two reasons; greater accuracy and/or finer surface finish (the two go hand-in-hand). When cutting using a "single pass", power settings are usually quite high and consequently the surface finish will have a "glass-beaded" texture to it after cutting. Additionally, two other factors can slightly influence wire position during the first pass of a wire cut -- electromagnetic forces on the wire, and high "flushing pressure" used to continually wash away the eroded material. These forces do not move the wire very much (a few tenths possibly), but this nevertheless affects accuracy (more so in tall parts). In order to achieve greater accuracy, multiple cuts are employed where the "offset" of the wire is reduced (easier to think of it as "spark gap"), and the electrical settings are altered (lower power and different waveform). When very fine finishes are required (Ra10 / 10 micro-inches or better ), as many as 1 to 5 additional "trim passes" can be used after the initial cut. Each pass will have less offset and lower power than the previous one. Whether it's fine finishes or ultra-precise tolerances that are required, multiple passes are the way it's done in wire edm.

What is the biggest limitation of wire edm?
The single biggest limitation of wire edm is that it must be possible to pass the wire by or through the part. The wire is continuous... so it's not possible to cut a "blind" cavity using wire edm.

Can complex shapes be cut?
Yes, within some reasonable limits. Most modern wire edm machines can cut up to 30° taper (or more precisely; the wire can be inclined up to 30°). Some machines can even go up to 45°. Note that since the upper axis on a wire edm machine is typically a "differential" axis (it translates relative to X/Y), a 30° angle is possible up to a certain part thickness, and after that the available angle reduces relative to the height of the part. Obviously if the part itself can be tipped or rotated, any angle is then possible. Using a rotary axis or a dividing head can allow cutting complex/multiple angle cuts. Additionally, the angle of the wire can be continuously changed (X/Y vs. U/V) while cutting, which allows the cutting of complex surfaces. Essentially; if a straight line can be passed along a contour, it can probably be cut by wire edm.

How accurately can you cut a feature on my existing parts?
The key words in that question are "existing parts". Since an existing part is often fixtured on a previously machined surface (or surfaces), the limitation in accuracy is often those already-machined surfaces. If a particular feature is cut via wire edm, that feature will have all the accuracy that the wire edm machine is capable of, but positional accuracy may be dependent on previous work. In a one-off situation, this issue can sometimes be partially negated by "touching off" on all previously machined surfaces and striking the best possible balance of dimensions to achieve positional accuracy. In production however, fixtures may be used that rely on previous machining to mount/clamp parts quickly, and if those parts are not consistent, accuracy may suffer.
Wire edm is really no different than any other form of machining in this regard, except that wire edm machines are typically much more accurate than other types of CNC machines, so small variations in accuracy from part to part become obvious and glaring errors when compared to what is possible in the wire edm machine.
Awesome!
Can I steal this?
Mark
 
snowshooze,

Of course! I have some other documentation as well that I always had online for "customer consumption". Let me chase it down. Anyone is more than welcome to use any of it.

PM
That is great.
I'll just put that right on my site, and hopefully, it will save me some explanation time, as well as give my potential clients at least a rudimentary understanding of the process.
Thanks!
Mark
 








 
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