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Thread: Swirls! Help!

  1. #1
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    Swirls! Help!

    I am a new conventional surfacing lab and when we ran test jobs everything looked great. Now that we have our first account we are getting swirls on the edges of all our lenses in all materials EXCEPT polarized lenses that are not cribbed. We have changed the polish, Use filtered water in the finer. Our generator is calibrated and every prescription is coming out perfect. We have adjusted the pressure and polish times all across the board. The only thing that made it slightly better was increasing our polish time to 5 mins, which seems crazy.

    I'm hoping for some suggestions on new things to try. Today we are testing to see if CR39 clear un-cribbed comes out without swirls since CR39 polarized un-cribbed didn't have them. But this doesn't make any sense to me. I thought cribbing was supposed to help. :/

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    OptiWizard
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    post the type of equipment/consumables you are using and post pictures of the lenses if possible.

    Polishing for less than 5min is on the lower side depending on the type of pad/polish/polisher you are using.

    without knowing the above, it's decently difficult to trouble shoot for you, as it could be a lot of different things.

    First suggestion would be to read your finer/polisher manual in the troubleshooting section, and contact your equipment and consumable supplier.
    They will know the most about this kind of thing.

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    RETIRED JRS's Avatar
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    Or, as a simple step, generate a lens with a reasonable back curve, and do a short fine test. A short fine test (5 second fining time) will show you whether you are; 1) fining from center to edge (bad), 2) equally fining (ok), or from edge to center leaving about a quarter-sized circle in center (best).
    J. R. Smith


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    Also check your air pressure regulators, filters, and remove any water that has accumulated in the system. Air compresses, water, not so much.

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    Master OptiBoarder MakeOptics's Avatar
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    I didn't see it posted so I'll add:

    Check the edges of your tool for any burs, file if necessary.
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    Doh! braheem24's Avatar
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    What's the diameter of your laps?

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    It's silly to ask but is your equipment calibrated correctly? At LC on the finers and polishers we had this big metal block we used to calibrate. Take some dirty grease from the 108 and smear it on the block then measure the pattern.

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    What was changed from test runs to production? Several variables can result in swirls. Quick and easy test is to process both minus and plus cr-39 with some cyl power
    (ie +2.00-3.00 and -2.00 -3.00) crib and run on foam lap and as a pair in the cylinder machines. Make sure water and polish are chilled to the apporiate temp (we run 55-60 degrees) If possible post pic post gen...post fine..post polish.

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    Generator is Coburn XRT, finer and polisher are LOH Toro-X-2S. We use Optisource polish all. And out pads are Coburn P800 blue.
    We are fining from the edge to the center.
    We have used brand new laps that we cut and still got the same issue.
    Here are some pictures. The first one is when we were polishing for 3 minutes. The second one has improvement when we upped it to 5 minutes, but they are still there on the edge.
    Click image for larger version. 

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    OptiWizard
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    what polish pad are you using?

    fining and polish psi/time?

    water and polish temps?

    Lap and block diameter?

    Not sure if it's the picture, but the first lens looks like it wasn't fined out enough before going to the polisher.

    Best thing would be to reread the manual for your finer/polisher.
    I've never worked with satis polishers before,
    but it could be anything, from stroke pattern, stroke speed, pressure, bad water/polish, water/polish temp, poor water/polish flow/direction

    could even be a defective batch of polish/fining pads

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    Doh! braheem24's Avatar
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    Is P800 a 1 step fine and 1 step polish? The first picture looks like the lens was just not polished enough or is skipping a step in the fining process.

    If so, skipping that second step is causing your issues.

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    Master OptiBoarder MakeOptics's Avatar
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    Quote Originally Posted by braheem24 View Post
    Is P800 a 1 step fine and 1 step polish? The first picture looks like the lens was just not polished enough or is skipping a step in the fining process.

    If so, skipping that second step is causing your issues.
    P800 is a one step pad. I never had much success with a one step process. That maybe the solution. I am curious to know the PSI as well, if the pressure is to low I know the lenses don't fine out all the way. Man, its good to see the surface techs come out of the shadows.
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    The swirls seem isolated to an area @ 45 degrees which is an axis issue or cut quality from the generator. Is the lens pictured poly? How do sphere powers polish? Post a picture of a poly lens with cylinder from generator before fining

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    We are doing a two step process for poly, and a one step for plastic. Do you do a two step process for plastic as well? If so, what pads do you use?
    I have done 10 second and 20 second tests and the lens is coming out smooth after fining.
    Our finer and polisher are measured in bar, not psi and we have ran anywhere in the range of .1-.8. The person we bought the equipment from said it should be ran around .4. Going above .8 almost made it impossible to lift the arms.
    We have tried fining anywhere in the range of 30 sec-2 mins. And polished from 1 min-5.5 mins. The first picture I posted is when polished for 3 mins, and the second was for 5.5 mins. Going above 5.5 mins is causing the tool to heat up and damage the lens.
    The swirls are not isolated to an area. It is all the way around the edge. I just couldn't take a picture of that. It is very difficult to take a picture at all! LOL! Both lenses are plastic, but it is happening on poly as well.

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    One more tip.. Put a heavy safety bevel. Perhaps if lens edges are sharp the lens is cutting the flock of the polish pad and all that is left is paper backer causing swirls. I would also check buame of polish..altough new might not be a good mix. We one step all materials with a 15 micron fine for plastic and a p1200 for poly.

  16. #16
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    given your equipment is running properly and the info you have provided, the most common problems are:
    -polish chiller isn't large enough to cool the polish late in the cycle, causing the block/lens to flex
    - you are having clogging issues at the edges of the lens
    - defective pads
    - your polish pump is giving out causing low flow late in the cycle

    could be a lot of other things

    I'll repeat, read your manual, talk to your consumables supplier and equipment manufacture

    they have teams of techs/process engineers that deal with this type of problem on a daily basis

    none of us can really help without inspecting your equipment personally

  17. #17
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    Thanks everyone! Lots of good suggestions here

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