FCZ UNDER 5 MINUTES

[Ken Knapp]

Milling the zicronia is not the problem.
It's the time it takes to sinter it. That's where the time saving is to be had.
You're looking in the wrong spot to "better, faster, cheaper" or whatever you called it.

Yes, sintering does take a while ~8 hrs. for 15-30.. units/cycle depending on oven. For a 30 unit/cycle that's 16min./unit which is on par with milling.
Sintering has the benefit of being a batch process. Whereas milling is serial, one crown at a time.
There are some quick firing furnaces on the market. Maybe flash sintering or another method could improve the sintering cycle time.
From a production flow view, the processes units/hr. should be balanced. A 8hr sintering cycle with 30 units should be fed by a mill that can produce at least 30units/8 hrs. or more because mill yield is lower than sintering...

 

[sidesh0wb0b]

serious thought, why not printing zirconia with some sort of binder? then sinter and off to the races

 

[Sevan P]

Why not All!
Faster , Better and Cheaper!

Because I like my soul and dont want to sell it to the Devil! You can sell yours if you like.......lol!

Sent from my SM-N950U using Tapatalk

 

[JayH]

serious thought, why not printing zirconia with some sort of binder? then sinter and off to the races

The difficulty is getting the suspension dense enough for the needed phase shift during sintering. IOW, the molecules aren't close enough together in a liquid state, or after they cool naturally from that state, so that sintering can have the desired effect.

 

[Affinity]

A printer couldn’t print a crown faster than 5 minutes, I don’t think.. but that seems fast. While I think that is the future.. I think zirconia might not be the product, maybe stronger composites or another sintered material that wears more like enamel.
The one thing I truly don’t believe is that we will still be milling zirconia in 15 years.. tooth regeneration therapy will be here before that.

 

[Ken Knapp]

serious thought, why not printing zirconia with some sort of binder? then sinter and off to the races

Tosoh already makes a zirconia3Y with binder used for injection molded zirconia.
Quality optical cearmics, like dental zirconia require precise control of sintered grain size, porosity and crystalline phases.

 

[adl]

Who can mill a FCZ crown within 5 min.?

Go away

 

[Ken Knapp]

Go away

Yes, it's important that zirconia binder goes away.
Is that your question?

 

[Jason D]

Yes, sintering does take a while ~8 hrs. for 15-30.. units/cycle depending on oven. For a 30 unit/cycle that's 16min./unit which is on par with milling.
Sintering has the benefit of being a batch process. Whereas milling is serial, one crown at a time.
There are some quick firing furnaces on the market. Maybe flash sintering or another method could improve the sintering cycle time.
From a production flow view, the processes units/hr. should be balanced. A 8hr sintering cycle with 30 units should be fed by a mill that can produce at least 30units/8 hrs. or more because mill yield is lower than sintering...

Agreed but sintering is still the bottleneck by virtue of its process time. Trying to speed up milking time is a waste mathematically, it’s like gunning the accelerator for a quarter mile only to stop at a rednlight every quarter mile, you don’t gain anything over the granny plodding along in the next lane cuz you will end up next to her at every light.
Plus mills are so damn cheap you should just buy or build more mills...
Now a better we process to ensure nothing is millled without intent and nothing is milled incorrectly is well worth the cost.

Additionally the post processing of sintered zirconia units is a much better place to spend time since batch processing produces instant queues due to large batch sizes, so cross training to have a finisher available for every 10 units in a sintered batch as soon as they are cool is a beautiful thing.

 

[sirmorty]

Well the simple answer is buy another mill or two.

 

[Affinity]

Why not just have the crown designed in under 30 seconds? Shave the time another way, build better algorithms.. then your machines and materials arent pushed. AI will be putting most of us out of a job soon enough anyway.. probably the same companies that are making us money now. Get it while you can.

 

[sidesh0wb0b]

The difficulty is getting the suspension dense enough for the needed phase shift during sintering. IOW, the molecules aren't close enough together in a liquid state, or after they cool naturally from that state, so that sintering can have the desired effect.

im aware, just hopeful that it might go that way some day! lol

 

[Doris A]

There's never enough time to do it right.....but there's always enough time to do it over.....

 

[Rockmuscle]

Yes, it's important that zirconia binder goes away.
Is that your question?

are you a re seller of Z mills? any recommendation for a cheap wet mill for Emax. I feel zirconia will phase out in the next 10yrs. cannot bond Zirconia to the tooth leading to secondary caries underneath the crown

 

[CoolHandLuke]

are you a re seller of Z mills? any recommendation for a cheap wet mill for Emax. I feel zirconia will phase out in the next 10yrs. cannot bond Zirconia to the tooth leading to secondary caries underneath the crown

it will be useful for you to know Ken Knapp used to be one of Glidewell's engineers.

on topic, i suppose i could write a sequence of 4 toolpaths, but the unit would come out still scalloped and will a lot of remaining material so wouldnt fit. i suppose 6 toolpaths would get a unit start-to-finish if the quality has to be there. would do one toolchange.

 

[adl]

Why not All!
Faster , Better and Cheaper!

It’s all in the eye of the beholder, if you know what I mean.

 

[CoolHandLuke]

alright, lets crunch some numbers.

roland 51d is rated to run 1800mm/min feed rate and max spindle speed 30k rpm

so assuming we're writing this for a roland 51d, a workNC cutting sequence for this would be as follows




Estimated machining time from the simulation


if i edit the stepovers...



so yeah it could work. i'm not going to break a machine or tooling trying it but heres math that it works on paper.

 

[CoolHandLuke]

the reason i like having the full open worknc for these kinds of things:



actual run time 4mins, toolchange sold separately.

 

[sidesh0wb0b]

how long did it take you to get to these calculations? @CoolHandLuke

 

[CoolHandLuke]

22 mins start to finish to plan the cutting, write the toolpaths, sort out errors, and do 2 simulations. 6 mins to photograph, and 1 to post.