Electrical discharge machining

suman

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Who know any manufacture of EDM? whos the best? Is this process gives incrediable passive fit for bars and screw retained bridges for real?
 
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Very limited knowledge here, but this would eliminate using titanium. The allow must be electrically conductive, I think. Its used for alloys that are usually too hard to mill. Again...very limited knowledge. Blasting away in a reverse welding type process, with loss on the electrode doesnt sound very accurate to me.
 
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Jason D

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this has been around for 30+ years, we were talking about those “perfect fit” sleeves in the 90’s, it was called spark erosion then, and produced awesome accuracy, I occasionally see these still around today.

I assume that cost was the limiting factor back then.
 
CoolHandLuke

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you can promise a lot with edm, but as alluded to earlier, only certain kinds of metals can be used unless you are paying for a realy powerul plasma machine.

edm is overkill; cnc machining of titanium and crco is very precise and low cost and works almost right out of the box.

you should really be equipped with renishaw touch probe scanner and proper cnc software to make bars, in my opinion.
 
suman

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That's an interesting concept to finetune fit... wonder what material the analogs are made of Hmmmm2Questionmark
I've contacted reseller. They give analogs for popular implant systems and their screw abutments. Work with Ti and CoCr.
 
kcdt

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I've contacted reseller. They give analogs for popular implant systems and their screw abutments. Work with Ti and CoCr.
You're going to spend a **** load of money to achieve with a casting what is already done with CAD CAM.
Edm is what we did before cad came along.
I don't see the point.
 
suman

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You're going to spend a **** load of money to achieve with a casting what is already done with CAD CAM.
Edm is what we did before cad came along.
I don't see the point.
point is that it is impossible for milling machine to archive passive fit on 8 implants, bar or multyunits whatever. Milling accuracy linearly decrease with linear dimension.
Of cause it is not about fitting crowns and bridges, cad cam do it much cheaper.
 
kcdt

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point is that it is impossible for milling machine to archive passive fit on 8 implants, bar or multyunits whatever. Milling accuracy linearly decrease with linear dimension.
Of cause it is not about fitting crowns and bridges, cad cam do it much cheaper.
Not what the research says.
I'm not buying into it.
 
kcdt

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Sources ?
Your search would be for papers related to passivity of fit in terms of longevity and complications.
My point being that the issues that endanger implants themselves are hygiene related.
I don't see what exactly is supposed to be gained by stepping backwards to achieve a level of fit already achieved by the mill.
EDM is only as good as the model you make to spark erode fit to. It's a goddam rabbit hole and a waste of profit.

There's a reason you can't find anyone doing it anymore.
 
CoolHandLuke

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point is that it is impossible for milling machine to archive passive fit on 8 implants, bar or multyunits whatever. Milling accuracy linearly decrease with linear dimension.
Of cause it is not about fitting crowns and bridges, cad cam do it much cheaper.
its not impossible.

its just complicated to get right. takes skill and a person able to operate a cnc with good habits. if each MUA needs to be +/-2um for passivity, then over 4 implants you will require a machine capable of repeatability of 4x2um (8um) and to acheive this you'll really want repeatability on 3um, and allow for 1.5um of runout. this will get you 5um on each hole center, and put you in the world of very tight fit.

its absolutely acheivable results.

its not something you want to promise same-day, and not something you should try to make a business from, unless you have absolutely cornered the materials and tooling market for this sort of thing.

one bar on MUA is a whole day's work. this accuracy demands stable, clean and slow toolpaths.
 
suman

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Its cant be true. CNC machine can have 1mkm accuracy on spindel movements. But process of producing burs and cavities which appears in process of milling cant give you less then 20mkm. It is limitation of process not cnc machine.
 
JMN

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Its cant be true. CNC machine can have 1mkm accuracy on spindel movements. But process of producing burs and cavities which appears in process of milling cant give you less then 20mkm. It is limitation of process not cnc machine.
If it is not posdible then please tell how so many havre been made.
 
CoolHandLuke

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well, you are entitled to your opinion.

i do want to know how you qualitatively measure your output, compare with design, and calculate your actual geometrical accuracy. do you scan your finished product? how?
 
kcdt

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If it is not posdible then please tell how so many havre been made.
Research has already more than quantified this as exceeding clinical acceptability.
Beyond that you're chucking profit down the rabbit hole.
I don't get it...
 
suman

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well, you are entitled to your opinion.

i do want to know how you qualitatively measure your output, compare with design, and calculate your actual geometrical accuracy. do you scan your finished product? how?
Sorry it is not about my product. I dont have such equipment to measure accuracy. Its the thing what Nobel says why we should not mill and produce bars and multiunit frames in milling centers. They give different investigations on this topic with numbers.
 
CoolHandLuke

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Sorry it is not about my product. I dont have such equipment to measure accuracy. Its the thing what Nobel says why we should not mill and produce bars and multiunit frames in milling centers. They give different investigations on this topic with numbers.
nobel has a vested interest in dissuading you from trying to mill bars. i hope you realize that.
 

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