Wire cutting tolerances

[cadman2112]

OK, I am NOT a wire guy

 

I am curious, what kind of part tolerances can be held when using a wire process?

[Del.]

OK, I am NOT a wire guy

 

I am curious, what kind of part tolerances can be held when using a wire process?

 

 

Less than a .0001/side on a good WEDM. A few tweeks under same conditions then almost Nuts.

[cadman2112]

Thank you Del

[Brad St.]

A few other items to consider are material, thickness (or varying thickness), wire, setups/flushing off the top of my head.

 

Del is correct, we were even using a surface profilometer to measure the cuts our charmille was making at one time to measure .00001" changes they were going for in some of our dies. then we got a zygo white light to measure items =)

 

Most of our dies need to be in the .0001" range for clearances, yes that number is correct unfortunately =(

[Del.]

Brad, Are you guys making some really small dies for thin material?

[mx247]

We have a couple Fanuc WEDM and can hold .0002 without much effort. Less then .0001 is possible but may take a few test parts to dial in your settings. The good thing I have found with wire machines is that they are very repeatable(less variables to worry about, tool condition, run out clamping force, etc.). If you have recurring work save whatever tweaks you made to the settings and the next time you will be good to go.

[Brad St.]

Del, it's .001" material that I'm not sure I can disclose publicly what it is but if it's not held that close for a tolerance it simply tears and does not cut clean. Thankfully the dies are yes smaller otherwise it would be an even more dreadful experience.

[Del.]

Del, it's .001" material that I'm not sure I can disclose publicly what it is but if it's not held that close for a tolerance it simply tears and does not cut clean. Thankfully the dies are yes smaller otherwise it would be an even more dreadful experience.

 

 

Cool Brad. I once saw a company punching and forming .0003 thick material. Amazing a Die set can be set that close.

[Newbeeee™]

Cool Brad. I once saw a company punching and forming .0003 thick material. Amazing a Die set can be set that close.

Del -what clearance between punch and die would you have? It would be slide fit surely?

[Del.]

Del -what clearance between punch and die would you have? It would be slide fit surely?

 

 

It wasn't something we did Newbee but another company I toured a long time ago when I was an apprentice. they said they were the only company that would take the job. My rule for clearance is 10% per side of material thickness so in this case .00003/side clearance for punch. Too close for me.

[Brad St.]

Yea, it's all relative. some designer or engineer will come up with a dream of needed more "strength" to a tool because it's chipping (carbide dies in 70RC D2 bases) so they make them 2" thick and draw them with those tolerances..... no thought about maybe it needs more lead in or clearance till the cut area to reduce binding...

 

then it's the whole knack of how to install the roller cages so they truly are "zero clerance" bearings with no hangups. It's an art in itself that i'm glad i don't have to deal with directly but just support.

 

awhile back we were having the issue of should we be press fitting our carbide dowels or going for a .00015" slip fit and putting a threaded end on them to retain them. i wrote up some programs to cut threads onto our carbide dowels using our 4th axis indexer on our one wire. worked slick as ever but we never went down that road. was still fun making the threaded carbide dowels and it only took minutes to do it.

[Del.]

Brad, I have the capability of the 4th axis on our wedm's but we don't have an indexer.I looked those things up and wow are they expensive for what little times we would need it. Why the carbide dowels?

[Brad St.]

Expensive YES. For our R&D we put the indexer and also purchased a 3R rotary spinner on one of our Makino's and they've proven to be some of the most impressive items for us.

 

Basically our dream teams (designers) will come up with items and have them SLA's or 3D printed here and then we get to make them. I think we've all heard the next statement "here it is just make it like this part it works".... so we do. The accessories simply save us having to make complicated fixturing which saves us time and time is money. Also giving us quality at the same time.

 

As for the carbide... no idea other than shock impact/toughness. It's one of those things that when questioned you'll hear "well this is how we've always done this". nuff said =)

[chris graf]

I have run a Charmilles Roboform 310 for years and on parts up to perhaps .5" thick .0001" is doable with a four pass program. On parts thicker than that the tolerance opens up a bit. I read up on this a bit and apparently when the wire is stretched a long distance between the upper and lower guides electromagnetic forces will bow the wire a bit and cause a "belly" in the part. The higher the current, the lower the tension and the greater the effect. That's why multi-pass cutting is required for more accuracy because each successive pass reduces the current and increases the tension. Of course more passes = more time = more cost.

[Del.]

Yes. I usually take 1 rough 3 skims to hold very tight tolerances. The belly can be compensated for by increasing or decreasing your SV servo voltage.

[chris graf]

I meant to say "Robofil 310" in my earlier. Can a message be edited here after it is posted?

[Del.]

I meant to say "Robofil 310" in my earlier. Can a message be edited here after it is posted?

 

 

Yes, Just click edit and then save changes