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

[rivfordental]

it looks like it ripped a chunk out of the zirconia, do you happen to know which tool did this? i would change tools right away. a gouge like that is either a dull, clogged or bent tool. being only in one spot, its definitely a tool clogging issue. the air sprays a tiiiiiiiny amount of moisture as it blows, this traps on the porous tool tip and causes tools to become clogged at the microscopic scale. then, you get big pits and chunks like this. since the moisture in the air varies, it has no frequency pattern and is unpredictable.

Thanks @CoolHandLuke

 

[zero_zero]

Hello @zero_zero could you explain more in detail?

Going slower with cutting you have less chances for chipping, your milling strategies consist of various cycles...one (or more) in particular is pocketing. This is delimited by the margin curve, pocketing is usually geared to deal with a rather simple geometry...if you got something complex like this:

I can cause issues, like chipping, since the tool will not necessarily retract going from one corner to another. By deleting the margin curve, it will force the CAM to mill the "inside" of the inlay with the cycle dedicated to the "outside". You could loose some detail, but in general it works. At least for my CAM setup, YMMV...

 

[rivfordental]

Going slower with cutting you have less chances for chipping, your milling strategies consist of various cycles...one (or more) in particular is pocketing. This is delimited by the margin curve, pocketing is usually geared to deal with a rather simple geometry...if you got something complex like this:
View attachment 36401
I can cause issues, like chipping, since the tool will not necessarily retract going from one corner to another. By deleting the margin curve, it will force the CAM to mill the "inside" of the inlay with the cycle dedicated to the "outside". You could loose some detail, but in general it works. At least for my CAM setup, YMMV...

@zero_zero thank you so much, i will try this.

 

[CoolHandLuke]

by deleting the margin curve the tools will follow the height of contour instead, when calculating finishing toolpaths.

 

[rivfordental]

by deleting the margin curve the tools will follow the height of contour instead, when calculating finishing toolpaths.

Hey @CoolHandLuke Is this an addition to what @zero_zero said?

 

[CoolHandLuke]

yes. maybe i'm mansplaining. maybe thats enough out of me lol

 

[rivfordental]

yes. maybe i'm mansplaining. maybe thats enough out of me lol

 

[user name]

It almost seems a tool is hitting your Zr when its not supposed to. Are you positive the correct thickness blank is entered?

 

[JMN]

and correct tool length, diameter....

 

[rivfordental]

Are you positive the correct thickness blank is entered?

Maybe i am asking a lot, sorry about that, but, i didn't understand this part

 

[JMN]

Maybe i am asking a lot, sorry about that, but, i didn't understand this part

if you are using 98 mm pucks they come in different thicknesses so a tall canine and such will fit.

 

[CoolHandLuke]

and correct tool length, diameter....

i'm not saying these parts of the cam don't matter, i'm just going to say they matter less in Vertical milling, and much MUCH more in Horizontal milling - for example in Imes 250i.

the correct blank thinkness does matter quite a lot though, because the initial plunge of the tool can prematurely damage it if it plunges too deep too fast. though, if this were the case, rivfordental would be complaining of too many used tools as well as gouges and chips.

 

[rivfordental]

i'm not saying these parts of the cam don't matter, i'm just going to say they matter less in Vertical milling, and much MUCH more in Horizontal milling - for example in Imes 250i.

the correct blank thinkness does matter quite a lot though, because the initial plunge of the tool can prematurely damage it if it plunges too deep too fast. though, if this were the case, rivfordental would be complaining of too many used tools as well as gouges and chips.

Well, we are using discs 98MMx18MM

 

[Glenn Kennedy]

Make sure the geometry of your tools matches the geometry specified in your CAM software. I think the shoulder on your 1mm tool is hitting the edge of the restoration during the finishing path. This is a very common problem when users change tool brands but don't update the tool geometry in the CAM software.

 

[rivfordental]

This new piece in the picture bellow, we milled it using the recommendation of margin curves deleted, and 90% milling speed. Still is chiping the margins,

 

[zero_zero]

This new piece in the picture bellow, we milled it using the recommendation of margin curves deleted, and 90% milling speed. Still is chiping the margins,

Bring it down to 15% or so, keep and eye on it to see when it does chip

 

[CoolHandLuke]

those are not small chips

 

[zero_zero]

This new piece in the picture bellow, we milled it using the recommendation of margin curves deleted, and 90% milling speed. Still is chiping the margins,

Normally it shouldn't chipped that crown... try some brand new burs, see what happens. Try touching the spindle while it mills, do you feel any vibration ?

 

[rivfordental]

Bring it down to 15% or so, keep and eye on it to see when it does chip

You mean to a speed total of 85% or 15% ??

 

[zero_zero]

You mean to a speed total of 85% or 15% ??

Total down to 15%