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    Wet Milling Zirconia?

    Discussion in 'Dental-CAM' started by Bryce Hiller, Nov 8, 2017.

    1. brayks

      brayks Active Member Sponsors Full Member

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      :)
      I thought you might be interested in this project we did back at one of our customers in 2009 testing some new tooling from ISCAR, Mastercam's adaptive machining toolpath and putting Radial Chip Thinning calculations to work cutting P20 tool steel, 1.25" diameter end mill. Heat was generated in the chips with air blast to keep them clear. Max temperature of the tool is shown in the image. You could grab the tool with you hand after machining was complete. Cool stuff.



      AssembledTool.JPG TempGage 73 Max Temp Shown.JPG
       
      Last edited: Nov 12, 2017
    2. Leejh

      Leejh New Member Full Member

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      I use shade layered discs and shaded non-layered zir discs. How would wet milling affect these discs?
       
    3. JMN
      Curious

      JMN Christian Member Full Member

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      Me likey. Thanks for sharing that.

      made me wonder though, at what point on what metric do you decide climb milling is neeeded or desirable. On those the cam went conventional, is it for the lower brittleness that conventional gets better results, is faster, et.c. than climb milling.
       
      Last edited: Nov 12, 2017
    4. brayks

      brayks Active Member Sponsors Full Member

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      I and not aware of any issues. Just be sure to follow the dry cycle as previously posted to make sure all the moisture is out of the unit(s).
       
    5. brayks

      brayks Active Member Sponsors Full Member

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      Actually it was all climb cutting relative to the stock remaining/being machined and the tool path calculated. The algorithm determines the most efficient path to maintain a constant chip load and constant contact (uninterrupted cut). In some causes an “island” (we say boss) may be created in an area which would cause a change in direction. Given the camera angle this would APPEAR to be a switch to conventional milling , but it is not.

      This, I believe brings up a good and mostly overlooked point. All CAM software is not created equal - they may or may not have these types of intelligent adaptive milling strategies or machining algorithms. Particularly Dental CAM software. I've seen competitive dental CAM software that actually does switch from climb to conventional milling. This causes a problem in terms of tool wear, less than optimal finishes and chipped margins.

      If you are looking for a new milling solution, CAM software and templates make a big difference and should be high on the criteria list in your evaluation. Among other criteria, look for CAM software that produces toolpath that is "dynamic" in nature and maintains constant contact with material, constant chip load and maintains direction of cut (climb vs conventional).

      Watch your units being machined, you can tell when this happens.
       
      Last edited: Nov 12, 2017
      • Informative Informative x 1
    6. CoolHandLuke
      Fiendish

      CoolHandLuke Well-Known Member Full Member

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      Climb Milling is highly and widely regarded in high speed Machining as more favorable than conventional Milling due to the fact that conventional Milling produces forces that would tear or rip the part but climb Milling will control the chipping so the forces are much better distributed upon the part and within the cutter enabling much higher cutting feed rate and cutter velocity
       
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    7. brayks

      brayks Active Member Sponsors Full Member

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      Indeed. When climb milling the cuttter basically pushes off instead of being drawn into the cut. This causes chatter, dramatically reducing tool life, dimensional accuracy and finished part quality. This is particularly problematic when using small cutters and or brittle stock,
       
    8. grantoz
      Amused

      grantoz Well-Known Member Full Member

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      gee i dont know how my zirkonzahn m5 has survived all these years still dry milling fine after nine years milling every day. the cnc ervice guy when i asked him when does he think the mill will need replacing said if you keep servicing it ,it will probably last another nine years with the odd repair here and there i asked him about the ball screws etc he said everything was all good and in the mean time i havent had to do all the extra drying and burning out for nine years thats a lot of time saved. i would dry mill if i were you.i have a wet dry zirkonzahn m4 but when i mill zirconia i still dry mill.
       
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    9. brayks

      brayks Active Member Sponsors Full Member

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      Cool.
      I think I may know some of the reasons for this success. Machine quality aside, the key thing here is likely servicing and processing restorations/materials within its capabilities. I am not sure what your production rates, restoration and material types, tool life, do-overs, quality etc are or what odd repairs he might be referring to or what odd repairs and down time you have had (all contributing to time, production and profit loss that can potentially be influenced by wet milling ), but, as I have experienced in my 40 years in the CNC/NC business (many as a CNC Tech), diligent preventative maintenance, quality ancillary equipment and proper usage will help extend any machines life as you can attest. Good on you for that.

      From what I have seen, diligent maintenance is not all that common with many labs and milling centers. Thanks for your post which should serve as a good reference to many.

      There are indeed many advantages to wet milling as our customers (small and very large labs and milling centers) who have switched can attest. I can only relate that these customers are enjoying the benefits and have no intentions of switching back to dry milling.

      That said, to each his or her own. I believe that one must experience both to really see what works best for them. Just my two cents YMMV...
       
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