Problems milling zirconia inlays/onlays with a Rolland DWX-52dci, chips and more chips

rivfordental

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Hello,
Thanks beforehand to the community.
TLDR, we are having problems milling Zirconia inlays/onlays, everytime the machine chips the job. We have changed the burs, calibrated the machine, we are using 3shape for the design. What are the recommended parameters in 3Shape for inlay/onlay/veneers. What is the recommended angle of the margin?
 
CoolHandLuke

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you'll want to doublecheck your sprue patterning, because inlays and onlays have different integral strength than copings and crowns. don't have cantilevers if you can help it, and generally you want a thick margin that you can finish flat with a bur or a diamond-rubber wheel. increase thickness to about 0.3 or more, to reinforce the margin to counteract the erratic table movements in such a small item.

turn the spindle speed UP by a maximum of 10% and leave the feed rate alone. alternatively turn the feed rate down a max of 10% and observe the vibration as the machine does its job. if its really vibrating, you'll have to try something else.
 
JMN

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When did you last clean the collet? It only takes a couple micron sized bit of detritus in there with the burr and the burr will have wobble.
 
rivfordental

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turn the spindle speed UP by a maximum of 10% and leave the feed rate alone. alternatively turn the feed rate down a max of 10% and observe the vibration as the machine does its job. if its really vibrating, you'll have to try something else.
How we can do this part.
 
rivfordental

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When did you last clean the collet? It only takes a couple micron sized bit of detritus in there with the burr and the burr will have wobble.
Thanks @JMN we recently did this.
 
rivfordental

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you'll want to doublecheck your sprue patterning, because inlays and onlays have different integral strength than copings and crowns. don't have cantilevers if you can help it, and generally you want a thick margin that you can finish flat with a bur or a diamond-rubber wheel. increase thickness to about 0.3 or more, to reinforce the margin to counteract the erratic table movements in such a small item.

Check this out @CoolHandLuke
 

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you'll want to doublecheck your sprue patterning, because inlays and onlays have different integral strength than copings and crowns. don't have cantilevers if you can help it, and generally you want a thick margin that you can finish flat with a bur or a diamond-rubber wheel. increase thickness to about 0.3 or more, to reinforce the margin to counteract the erratic table movements in such a small item.

turn the spindle speed UP by a maximum of 10% and leave the feed rate alone. alternatively turn the feed rate down a max of 10% and observe the vibration as the machine does its job. if its really vibrating, you'll have to try something else.
Double up spruces on veneers.
 
zero_zero

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You have to throttle back your feedrates for inlays to mill correctly, might also check your strategies if they behave properly... deleting the predefined margin curve might help as well.
 
rivfordental

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@CoolHandLuke this are the parameters we are using, any suggestion?
 

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CoolHandLuke

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no suggestions, but a question: does it chip in the same position every time, or is it different?
 
rivfordental

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no suggestions, but a question: does it chip in the same position every time, or is it different?
In the case of the first pictures it breaks on the top right corner of the inlay, the 4 times we tried this case. But in other cases it chips randomly.
 

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rivfordental

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Feed rate is how fast the burr is going along the material as it cuts.
Spindle speed / RPM is how fast the burr spins as it moves along the material.
Do you have settings set? What i need to do in Vpanel?
 
CoolHandLuke

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index.png

in this menu override the Spindle speed OR the milling speed - i would follow Zero's advice and LOWER the Milling speed by about 10% maximum.
 
JMN

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Do you have settings set? What i need to do in Vpanel?
I think you would do yourself a huge favor by attending the classes @brayks of Axxsys is giving.

Find out how to run your machines without them running you in circles.
 
rivfordental

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I think you would do yourself a huge favor by attending the classes @brayks of Axxsys is giving.

Find out how to run your machines without them running you in circles.
thanks @JMN i will check this
 

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