Hole sizes on Sodick AG600L

[nlancaster]

So, for the last few years I have been doing most of the programing for our 2 Sodick AG600L machines.

I have always had to adjust the hole size with extra offsets usually negative amounts to make the hole larger.

Example:

Bore starts as a .140 precision bored hole, with less then .0005 runout to the OD of the part.

I use conditions for open cuts as the bore is large so do not get a good seal.

Program a .1503+/-.0002 hole and the initial size will be .148ish.

Slots on the OD of the same part with the same offsets will be within .0005 of nominal, .035

Then I have to make adjustments with FLAG7D, a global offset adjustment for the hole, of -.0015ish varies program to program.

Anyone have any experience on why this may be happening?

 

[OffsetLeft]

If it comes to you 'precision bored' to .140 - Why don't they just take it to size and let you cut the slots?!?

Dan

 

[nlancaster]

I have said that more then once. Engineer wants it done this way.

And that was just an example, I have other parts we run that are only drilled .140ish all the way thru ant 1.5 inches tall.

 

[OffsetLeft]

I have said that more then once. Engineer wants it done this way.

And that was just an example, I have other parts we run that are only drilled .140ish all the way thru ant 1.5 inches tall.

 

[JZ.]

So, for the last few years I have been doing most of the programing for our 2 Sodick AG600L machines.

I have always had to adjust the hole size with extra offsets usually negative amounts to make the hole larger.

Example:

Bore starts as a .140 precision bored hole, with less then .0005 runout to the OD of the part.

I use conditions for open cuts as the bore is large so do not get a good seal.

Program a .1503+/-.0002 hole and the initial size will be .148ish.

Slots on the OD of the same part with the same offsets will be within .0005 of nominal, .035

Then I have to make adjustments with FLAG7D, a global offset adjustment for the hole, of -.0015ish varies program to program.

Anyone have any experience on why this may be happening?

How many passes are you taking? Being that you only have .010 stock in the hole your, first pass isn't engaging much. I tend to take .001 off H001 and around .0005-.0007 off H002. I always feel the offsets come in slightly heavy for my typical conditions I am cutting in.

Are the cutting conditions the same for the slot? That is somewhat odd for it to be different size wise for the same offsets, unless where the feature is being cut has better flushing giving you a better overall burn on that feature.

 

[nlancaster]

So the cutting condtions for the slot are probably worse if anything. The OD of the part is stepped.

 

[JZ.]

So the cutting condtions for the slot are probably worse if anything. The OD of the part is stepped.

I see, is the slot the same thickness as the hole? Or since it is stepped is there less material to cut through?

 

[implmex]

Hi nlancaster:
I see this happening every time a condition of asymmetric flushing occurs.
The wire is deflected toward the side where there is no wall on the kerf.
So you get a hole that's undersized and is smaller in the middle than close to the wire guides.

I'll bet if you made the wire start hole significantly smaller, your size control problems would go away.
Of course you'd then have slugs to deal with.
Once you do a first skim, the problems go away and you can begin to rely on the subsequent skims to remove the predicted amount of material.

Similarly when you do a no-core cutting strategy you get the same effect in the hogging passes where you don't care, but you do the first skim to clean up the sidewalls, so the remaining skims become predictable.

Moving on to why cut the hole when you cut the slots...a credible explanation is that when you cut everything together, all the relationships become as accurate as the machine is accurate, and the accuracy of the setup and touch off is removed from the equation.
As all of you with wire experience know, getting touch offs consistent within tenths can be very difficult, and I'm sure you've all held your breath when the round part with the hole that's supposed to be in the middle goes on the measuring device and gets interrogated for concentricity.
If the relationship of slots to holes is the important thing, then the strategy of cutting everything together makes sense.

So why bother to make a precision start hole?
Because even if you cannot rely on that hole to get the hole wall to slots relationship perfect, it still is a most convenient place to do a wire touch to get the location of the feature within very close limits relative to the other features on the part.

So yeah...I see the possible merit in doing it as the engineer has prescribed...they're not ALL idiots after all.

Cheers

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

 

[nlancaster]

Marcus, yes I believe you are correct. Even though the only tight tolerance is the ID to OD the slots have a +/-.005 tolerance.

And yes I think you may be right on the bore to skim ratio.

I am doing 4 passes.

The part then gets glued up with 3 other parts and a bunch of ceramic, we use the bore to align the part and enlarge the bore and cut the parts into 8 segments glued to ceramic.

The outer OD slots are stepped they start out about 3/8 drop down to about 1/8 then increase when they touch the central barrel of the part to 1-1.5 inches depending on the part.

 

[plastikdreams]

What is your feed rate when making the hole?

 

[Shane030173]

Which cutting condition are you using? With that tight tolerance you should be using a water 5. I normally do a rough and 3 skims. I have noticed the pika setting on the 4th skim gives a great finish but seems lose accuracy.

 

[nlancaster]

Sodick conditions are different then what I think you are refering to, I am using C001-C004

 

[plastikdreams]

What is your feed rate when cutting the hole?

 

[Shane030173]

Sure they're the actual cutting conditions for rough and skims. If your AG is a LN2W control there are different water conditions in your condition search.

Water is your least accurate but will give a pika finish with 3 passes.

Water 2 is a 2 pass cut. A rough and pika pass. I dont use this.

Water 3 is your all around good condition to use.

Water 5 is the high precision condition. This is a little slower in skim passes but will give the most accuracy and straightness.

 

[nlancaster]

Nope, only option that says "water" is the first choice in the condition search.

Then select wire diameter, wire type, material, thickness of part, punch or die, nozzle position, and finally how many passes.

The cuts on the part are using C001-C004 with conditions from the condition search.

Plastikdreams, varies, depending on condition. The hole it self takes about 6 minutes to complete all passes, 4 passes total.

 

[Shane030173]

Once you select # of passes and the slide bar pops up for finish and accuracy. If you move your pointer over the precision number it will show which water condition it is.

 

[nlancaster]

Shane, never noticed that before. I think I am on water 3, but honestly its been several weeks since I wrote this particular program so I don't know for sure.

 

[plastikdreams]

Can you put the machine into a non varying speed and cut at like .03 ipm?

I'm having a similar issue cutting basically an oval, flat sides are dead on but the radius sides are under .00015 per side. Not sure wtf is going on lol.

 

[Waakzaamheid]

As Marcus said, your issue is your start hole is too close to the finish size. If you can't make the start hole smaller so you're actually dropping a slug, then what I usually do in this case is bump up my servo voltage significantly on the skims. This will slow down your cut speed and also the wire to straighten out the hole. A newer Sodick is one of the few machines I haven't actually worked on, but I assume there's a way to create a modified technology setting to use for the hole, and a different one for your slots.