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Thread: FreeForm technology

  1. #1
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    FreeForm technology

    Hi,

    I was wondering if anyone could correspond with me in regard to freeform technology. I am particularly interested in problems relating to cutting and polishing, but am also looking for information on post-polish marking of the lenses.
    Any other forewarnings regaring teething problems would be helpful and appreciated!

    Thanks.

  2. #2
    OptiBoard Apprentice Thomas's Avatar
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    If you're talking about marks from polishing......
    We get very fine scratches on all materials, they seem to be on poly more and cr39 less. The lenses look almost milky sometimes with the haze. If they're not bad (and they never really are), we just hard coat them and they disappear.

    Hope this helps.
    :cheers:

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    Thanks Thomas.

    The milkiness, is it on CR lenses as well? When are the lenses checked milkiness?
    What type of hardcoating/machine do you use?
    Do you engrave your lenses and how is that working for you? Do you stamp them after engraving?

    Sorry to be asking all the questions, but I am just going through some of the possible issues i may be encountering.

    Thanks for any information you are able to supply.

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    OptiBoard Apprentice Thomas's Avatar
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    The "milkiness" seems to be only with the poly that we do. The other materials just seem to show only very light scratches. As I said, coating takes care of all this. You can only see this level of imperfections after de-blocking at inspection before coating. If you could see it before de-block then coating would not cover it. As a rule we hard coat all free form lenses because of one thing or the other.
    At this time we are not doing any progressives so marking/engraving is a non-issue. ......something to look forward to......
    We are using an Ultra Optics Mini 2 spin coater.

    I hope this helps.......:cheers:

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    Confused marking free form lenses

    Im going to start free form lenses production and we need problems that Ill found with marks by laser, hard coating,..... Ive heard that alkaline products in washing process afect at the quality of marks, Its true?

  6. #6
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    Quote Originally Posted by fcl View Post
    Im going to start free form lenses production and we need problems that Ill found with marks by laser, hard coating,..... Ive heard that alkaline products in washing process afect at the quality of marks, Its true?
    Yes, for what I know, alkaline products etch the mark. Too much etching and mark can't be see.
    The laser burn microscopic holes on the lenses. For every hole you have a bump. This is what you see.
    Too lite bump and hardcoat will cover everything, and too big bump and hardcoat will increase it and you will have pit on your lenses.
    The laser need to be very well ajust to be able to see the mark without doing pit. :angry::hammer:

    Good luck

  7. #7
    OptiBoard Professional Mauro.Airoldi's Avatar
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    It's not a US troubles, the disappearance of laser mark is connect with substrate you use, the laser energy and the temperature of the post curing treatment.
    to explane better:
    different substrate with the same laser energy produce differet marks
    the same marks but in different substrate can be removed during the curing by heating (if you use dipping and heating polymerization system).
    tipically the most sensitive lenses are in 1.66 and 1.74 materials that are very sensitive and you have to use or high power on laser os low temperature for long time. (troubles upper 100-105c).
    Like everithing the laser power is a compromise but MUST be adjust with index materials.

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    free form marks

    Ciao Mauro, Sono Francisco dalla Visionlab, Mi ricordi? tu sei stato da me facendo il collaudo della mia S900DL.

    Se non capisco bene, debo fare un processo per ogni sustratto, con diverse potenze dell laser. Per cuanto riguarda alla temperatura, Vuol dire alla temperatura di polimerizzazione della laca?

    For Didier. Thank you for your reply. I think that problems could be with residues of those holes. I they are not take out correctly in washing process post polishing, I could have troubles in hard coating. Do you know anything about it?

    Thanks

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