How do you calculate your machine rate?

Hi all,

We recently added sinker EDM to our machine shop capabilities, mostly because we do a lot of one off repair and/or reverse engineering work. We bought a used CNC sinker with a C-Axis which gives us a lot of options as far as what we can do. And I am finally getting my head around the process and able to actually use the machine for real work. (I was having trouble nailing sizes but thanks to the people here I have that mostly sorted now).

My question now is what should sinker EDM work cost? And how do you decide? I don't really want to be the guy that asks the "what do you charge" question but I am at a total loss in this case. I have zero experience working in an EDM shop or quoting EDM work. All I really know at this point is "it's not cheap".

Between time to make the trodes and the actual sinking time it's just really slow. We bought the machine planning to mostly run unattended during the day and overnight as much as possible, so it's not like there is a lot of labour beyond setup. Also we got the machine fairly inexpensive so not a lot of capital overhead. But even small features take 2-6 hours minimum (assuming decent finish). Add to that 1-2hrs to make a couple simple trodes and setup the machine puts me at a minimum of 6hrs for a single feature. Often a lot more.

So what is reasonable? I can't imagine charging full shop rate for EDM run time, but the trode machining and machine setup needs to be...otherwise we might as well run other machines.

Right now I just take a guess at the labour cost portion and a token charge for the EDM run time. I'm still learning after all. But that is not sustainable long term. Trying to figure out a fair market value.

Thanks in advance.

Levi

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Edm is a specialty and can be billed as such. Of course burning out a stuck bolt or broken thread can carry a lower price, full on burns can easily be over 150/hour. I've never been on the quoting end of sinker work, Marcus (implmex) I'm sure can give you a better breakdown.

I thought you just took how much money you want to make and divided by how many hours you feel like working. There's your rate !

1-2 hours to cut a simple electrode, 6 hours to edm it. Be cheaper to send it out. You have some work ahead of you.

I don' know the answer, because I'm in the same place. I do know that when the machine goes down and you call in a tech & buy parts you will wish you charged more money & saved it in a separate bank account. Also you need to think ahead about having money to upgrade to better machines as this one gets older, less reliable, and the new machines are too fast to quote against. In my case I am so far just dabbling with an old machine to get my beak wet. I'm already wishing for a newer machine.

Leviathan said:

Hi all,

We recently added sinker EDM to our machine shop capabilities, mostly because we do a lot of one off repair and/or reverse engineering work. We bought a used CNC sinker with a C-Axis which gives us a lot of options as far as what we can do. And I am finally getting my head around the process and able to actually use the machine for real work. (I was having trouble nailing sizes but thanks to the people here I have that mostly sorted now).

My question now is what should sinker EDM work cost? And how do you decide? I don't really want to be the guy that asks the "what do you charge" question but I am at a total loss in this case. I have zero experience working in an EDM shop or quoting EDM work. All I really know at this point is "it's not cheap".

Between time to make the trodes and the actual sinking time it's just really slow. We bought the machine planning to mostly run unattended during the day and overnight as much as possible, so it's not like there is a lot of labour beyond setup. Also we got the machine fairly inexpensive so not a lot of capital overhead. But even small features take 2-6 hours minimum (assuming decent finish). Add to that 1-2hrs to make a couple simple trodes and setup the machine puts me at a minimum of 6hrs for a single feature. Often a lot more.

So what is reasonable? I can't imagine charging full shop rate for EDM run time, but the trode machining and machine setup needs to be...otherwise we might as well run other machines.

Right now I just take a guess at the labour cost portion and a token charge for the EDM run time. I'm still learning after all. But that is not sustainable long term. Trying to figure out a fair market value.

Thanks in advance.

Levi

Sent from my SM-G965W using Tapatalk

Click to expand...

At the shop I am at, when we have electrodes to machine they are put on their own separate job with "x" amount of hours to machine, then the next process (edm) has it's own separate job. Easy to track hours and errors for us.
Then what my boss likes to do both with WireEDM and Sinker quotes is "Man Hours" on the job. Could be a 10hr burn but might give me 3 or 5hrs to set-up, program and run it and overall I might have 2hr on it given everything goes well. There are pros and cons as with anything but it has worked for us. Good Luck

There is a big EDM shop that specializes in cooling holes for gas turbine components. They used to charge $1/hole. They have thousands of machines, and EDM a little more than 3M holes/day. That could be anywhere from $60-700/hr per machine.

Hi Leviathan:
It's a multifactorial question for sure, and you have a couple of ways to get there.
One good way is to score a job that's complex enough to need a reasonable amount of attention for trode making, for setup and for burning.
Estimate the job in your preferred way and keep the number to yourself.

Farm it out to a dedicated EDM shop and get them to give you a quote.
Pay them what they ask and have them do the job.
Evaluate it for its quality and then compare your guess with their quote.
Charge the customer a small markup and learn from the experience.
That gets you into the ballpark of what's competitive in your area.

What it takes depends on a lot of factors, and you need to decide which apply to you.
If you are confident with a milling machine, you can quote the trode(s) the same way you quote any other milling work as humanrobot suggests.
The prices for trode material are readily available.
If you choose graphite you need to charge for cleaning up the mess afterward.

Quoting the setup is similarly straightforward.
You should have a pretty good idea what it will take just from looking at the job.
I typically allocate 1/2 hour per setup at my usual charge out rate, and that's been pretty good for me...I win a few and lose a few but I mostly spend just about what I've estimated by the time I've noodled around fixturing the part, touching off the part, setting up and fiddling the flushing, writing the code filling the tank and hitting the green button.
It's more if there is crazy shit involved like building custom fixtures, vectoring in at weird angles, hitting ridiculous tolerances, burning big awkward jobs, complex interrogation etc etc.

But if it's just a simple blind keway it's 1/2 hour to set it up even if it only actually takes me 10 minutes.
I quote it high to keep the cheapass dickweeds away and to get a decent return for all the hassle of owning and maintaining the technology.

The burn time is the kicker with this work.
A lot depends on how good your sinker is...mine is really basic so it's not even remotely competitive in burn times with a more sophisticated model.
If I'm doing time consuming but uneventful burning in virgin material (like a new mold cavity) I charge at a low rate for the actual burn time in order to stay competitive enough not to get a reputation for gouging my customers.
I'm definitely not the cheap guy that gets all the crap work...I try to stay right in the middle of the pack.

So a guy with a nice Mits or Charmilles might burn for an hour on a job that I have to burn for 5 hours...I charge what he would charge, not my shop rate times however many hours it took me.
Most of it the machine just burbles away in the background anyway...I don't care enough how long it takes to be motivated to buy a better, faster machine...I make my money on the trode and the setup and the fact that I can attract and retain customers because I can do a broad range of work for them.

On a last note: BEWARE the broken tap and the broken drill type jobs...they can and will break your heart sooner or later!
The problem is you don't know how many broken shards and how many chips are packed down there; all just waiting for a chance to short your trode and stall the burn.
Ditto for broken studs...yeah you can burn out the core pretty quick but you can fuck around half of forever trying to find the location accurately and trying to get the little triangular wire out of the thread once you've burned away the core.
It can be super easy or it can be a schedule destroying bitch and you never know which it's going to be until you're sitting in it.
I discourage it by insisting on cost plus, and if it's a homeowner with a fucked up lawnmower I jack up my hourly rate too and make him wait a month.

For serious customers, I negotiate a "Not to Exceed" price and I make them understand that if I can't finish it for that price, they are still going to pay me for my time or pay more to have me complete the job.
I let them know beforehand that these jobs cannot be estimated...they're going to take whatever they take and that abandonment of the job will sometimes be the best way forward.
I then let them choose if they wish to proceed and I make them deposit the maximum we agreed on before we begin.
If it comes in cheaper, I refund the surplus.

I got to be such a dick about it because I had to do too much fighting with non-paying assholes after the job was done or partly done...so cash up front or I'm not interested.

Good regular customers I don't treat that way but casual walk in's...you betcha!
Those that can't handle it are invited to find someone else.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Thanks to everyone for your comments!

A lot of good thoughts and input. I can't say I really know enough yet to have a "rate" figured out per se. Probably right now I'm doing well if I get regular shop rate for my man hours and materials. Especially since it takes me some messing around to get things tweaked some times.

But thanks to people's input on this and my other threads I am steadily making progress. The information for the erosion tables on this machine is vague at best. But I have kept experimenting and my burn times are steadily getting less. I did some internal splines in a blind hole last week and they came out really nice.

At this point I'm just trying to keep the machine running pretty steadily so I can keep building on what I'm learning. So far so good.

Thanks again!

Levi

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An edm crawls along like watching corn grow.
Does the corn growing time get the same rate as planting and harvesting?
Bob

CarbideBob said:

An edm crawls along like watching corn grow.
Does the corn growing time get the same rate as planting and harvesting?
Bob

Click to expand...

Exactly why I'm asking. Setup and electrode manufacture are basically like regular machine shop work in terms of pricing, but the actual run time on the machine can't be free, not that it can't be covered as part of a general "shop rate" but it would be cleaner if the run time rate was more reflective of the cost. Machine cost (whether bought outright or leased), electricity, dielectric fluid, wear and tear on the machine/maintenance cost.

Therefore, my assumption is an old piece of crap machine that takes 24hrs to burn a cavity can be cost competitive with a brand new machine that burns the cavity in 2hrs. Assuming the cost of machine ownership is low enough and all other things are equal.

Example: hourly burn cost for a $200,000 machine (ROI 60months based on burning 24hrs/day 5 days/wk) would have to be around $28/hr without accounting for anything else. Plus or minus based on number of hours it is realistic to be actually running, setup time obviously brings in income, but reduces machine running hours.

Partly why I asked the question is because EDM is so different than conventional machining in that it can run basically unattended for such long periods of time with very low consumable costs making it an interesting animal from a costing perspective. I suspect people have widely different ways of coming up with their final number. Especially since I suspect most work is quoted ahead.

Interested to hear more thoughts from people.

Levi

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Hi again Levi:
Looking at it from the point of view you outlined, there are a couple of take home things I can describe;

First...a "crap" sinker EDM cannot do many things that a "good" one can, and much of the well paying modern EDM work requires those abilities.
Accuracy, finish, ability to orbit and to vector in any orientation, the ability to rotate an electrode are not just conveniences; they are necessities if you want to be able to quote typical sinker work.
For example:
I have two possible strategies to burn a simple hex into a part:
1) I can make a full sized hex trode and drop it into a pre-drilled hole, burning down as I go until I reach the bottom, then changing and reorienting an new trode to pick out the corners where the trode wore.
2) I can make a small enough trode that I can drop it into the pre-drilled hole without it touching the sidewalls and then vector it into each corner of the hex in succession.
If I want a perfect pointy hex I can preserve one side of the trode by indexing it between vector burns with the C axis so the same corner sees all the roughing wear, and I've still got dead sharp corners and untouched flats on the trode to do the finishing.

Way #2 makes a way better hex, way faster, and I can typically use only a single trode of an almost arbitrary size and still get exactly the hex I want, within tenths if I need it.
The difference in costs is remarkable...1/10th of the burn time, 1/4 of the trode making time and cost, 1/10th of the fucking around to measure what I'm getting.
Modern CNC sinkers can do this...clunkers cannot.

So the capability is important in a fundamental way if you are advertising yourself as an EDM vendor and are soliciting EDM contract work.
On the other hand, if you view it as an internal shop convenience that gives you the balls to power tap inconel for example, secure in the knowledge that you can always just extract a broken tap, the calculus is different, and you need not care in the same way.

A second often overlooked point:
If you need to make many trodes to get through the burn you will need to spend the money and materials to make all those trodes, and set them up and orient them into the burn and etc etc.
So a sinker capable of orbiting a single trode for both roughing and finishing orbits and not wearing the shit out of it in the process saves money, and not just in the burn time as in the above hex example.

Moving on to the costs of running the machine:
If yours is like mine, you will need to do very little fixing...I've owned my Hansvedt CNC sinker for twenty years and I've put a couple of thousand bucks into it.
But if you have a high end Swiss machine, you can get a huge and rude bill for even the most trivial problems like a blown monitor or an Eprom gone bad.
With EDM machines it's always a crap shoot; they all have stars and they all have lemons (even new ones) and only the Gods decide which you'll get.

For basic running costs, there's power (depends on how big your trodes are) dielectric oil (expensive but rarely changed unless you accidentally pour it all on the floor when you whip the tank door open before draining it), filters for the dielectric oil, the time and cost to keep the machine clean, and that's about it.
Unlike wires, there's not a lot of fussy little shit needing constant attention...no wire, no guides, no power contacts, no DI resin, no discharge cables...it's pretty simple.

Also fixturing tends to be simple and cheap (a mag chuck and a toolmaker's vise) unless you really go to town and get the full meal deal from 3R for your trodes and your workholding too.
If you want to build an efficient system it's worthwhile, but if this machine is in a mostly maintenance shop, not so much.
BTW you can drop fifty grand into a nice 3R system without even trying hard.

On a last note...if you plan to run unattended, please do make sure your fire suppression system works...the big hazard is burning your shop down overnight when a hose breaks, the tank level drops, and the whole shit catches fire.
Less of a problem now that no one in their proper senses uses kerosene for their dielectric anymore, but still worthy of respect.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

When the endmill starts melting, I slow down

SteelrFn said:

When the endmill starts melting, I slow down

Click to expand...

I agree, that sounds like it is arcing and not eroding properly. Check your flushing, back off on your SV, bump up your gap voltage and maybe drop your I value. The real question is why use an endmill for EDMing?

Levi - check your PM's please.

implmex said:

Hi again Levi:
Looking at it from the point of view you outlined, there are a couple of take home things I can describe;

First...a "crap" sinker EDM cannot do many things that a "good" one can, and much of the well paying modern EDM work requires those abilities.
Accuracy, finish, ability to orbit and to vector in any orientation, the ability to rotate an electrode are not just conveniences; they are necessities if you want to be able to quote typical sinker work.
For example:
I have two possible strategies to burn a simple hex into a part:
1) I can make a full sized hex trode and drop it into a pre-drilled hole, burning down as I go until I reach the bottom, then changing and reorienting an new trode to pick out the corners where the trode wore.
2) I can make a small enough trode that I can drop it into the pre-drilled hole without it touching the sidewalls and then vector it into each corner of the hex in succession.
If I want a perfect pointy hex I can preserve one side of the trode by indexing it between vector burns with the C axis so the same corner sees all the roughing wear, and I've still got dead sharp corners and untouched flats on the trode to do the finishing.

Way #2 makes a way better hex, way faster, and I can typically use only a single trode of an almost arbitrary size and still get exactly the hex I want, within tenths if I need it.
The difference in costs is remarkable...1/10th of the burn time, 1/4 of the trode making time and cost, 1/10th of the fucking around to measure what I'm getting.
Modern CNC sinkers can do this...clunkers cannot.

So the capability is important in a fundamental way if you are advertising yourself as an EDM vendor and are soliciting EDM contract work.
On the other hand, if you view it as an internal shop convenience that gives you the balls to power tap inconel for example, secure in the knowledge that you can always just extract a broken tap, the calculus is different, and you need not care in the same way.

A second often overlooked point:
If you need to make many trodes to get through the burn you will need to spend the money and materials to make all those trodes, and set them up and orient them into the burn and etc etc.
So a sinker capable of orbiting a single trode for both roughing and finishing orbits and not wearing the shit out of it in the process saves money, and not just in the burn time as in the above hex example.

Moving on to the costs of running the machine:
If yours is like mine, you will need to do very little fixing...I've owned my Hansvedt CNC sinker for twenty years and I've put a couple of thousand bucks into it.
But if you have a high end Swiss machine, you can get a huge and rude bill for even the most trivial problems like a blown monitor or an Eprom gone bad.
With EDM machines it's always a crap shoot; they all have stars and they all have lemons (even new ones) and only the Gods decide which you'll get.

For basic running costs, there's power (depends on how big your trodes are) dielectric oil (expensive but rarely changed unless you accidentally pour it all on the floor when you whip the tank door open before draining it), filters for the dielectric oil, the time and cost to keep the machine clean, and that's about it.
Unlike wires, there's not a lot of fussy little shit needing constant attention...no wire, no guides, no power contacts, no DI resin, no discharge cables...it's pretty simple.

Also fixturing tends to be simple and cheap (a mag chuck and a toolmaker's vise) unless you really go to town and get the full meal deal from 3R for your trodes and your workholding too.
If you want to build an efficient system it's worthwhile, but if this machine is in a mostly maintenance shop, not so much.
BTW you can drop fifty grand into a nice 3R system without even trying hard.

On a last note...if you plan to run unattended, please do make sure your fire suppression system works...the big hazard is burning your shop down overnight when a hose breaks, the tank level drops, and the whole shit catches fire.
Less of a problem now that no one in their proper senses uses kerosene for their dielectric anymore, but still worthy of respect.

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining

Click to expand...

Thanks for taking the time to write such a detailed reply Marcus. Quite a wealth of useful tips there. Some I have run into already, some totally new things to think about.

Re: Fire Suppression....for anyone who doesn't have it....get it. We had a shop fire about 2 years ago (lightning started a slow burn in the attic....didn't show up for two days). Took a solid 1.5years to get things back close to normal....and the actual fire damage was minimal. Smoke and water did most of our damage.

Anyway thanks again.

Leviathan



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