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Thread: Bayer Test Problems

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    Bayer Test Problems

    Hello,

    We are having some problems with our Bayer Tester. Just wondered whether anyone out there has seen this before.

    Our testing machine is quite old now and showing signs of wear. Instead of the carriage just going back and forth 600 times in 4 minutes, it jumps up and down a bit as it goes. All our results are down on what we used to get, and we do not really believe that this is because all our coating machines have developed problems at the same time. Cross checking coated lenses from other labs confirms that our results are coming out too low.

    Apart from asking for a new Bayer Testing machine, can anyone suggest a work around, or a reason to explain what may be happening?

    P.S. Lenses from the last batch showed strange patchy markings, apart from the usual haze.

    Many thanks,

    Falstaff

  2. #2
    OptiBoard Professional Mauro.Airoldi's Avatar
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    The Bayer test is a test of reproducibility with many problems.
    That uses abrasive?
    The base in the test lenses is 5 +/- 1?
    What value of Haze get on CR39 lens? (Usually must be between 13 and 17)
    I personally found problems in relation to the efficiency of the abrasive oschillazione system, often a maintenance in oscillating system makes the movement less jerky and thus the acceleration of the abrasive on the plate changes.
    Note: with the last batch of abrasive I found a decrease of needed results from 14 to 6, but remember the Bayer don't give you linear result... the difference betwen 10 and 15 is not like the difference betwen 5 and 10
    let me know

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    Quote Originally Posted by Mauro.Airoldi View Post
    The Bayer test is a test of reproducibility with many problems.
    That uses abrasive?
    The base in the test lenses is 5 +/- 1?
    What value of Haze get on CR39 lens? (Usually must be between 13 and 17)
    I personally found problems in relation to the efficiency of the abrasive oschillazione system, often a maintenance in oscillating system makes the movement less jerky and thus the acceleration of the abrasive on the plate changes.
    Note: with the last batch of abrasive I found a decrease of needed results from 14 to 6, but remember the Bayer don't give you linear result... the difference betwen 10 and 15 is not like the difference betwen 5 and 10
    let me know
    Hi Mauro,

    Thanks for replying.

    The haze change we get normally on the CR39 lenses is just over 20%. This is normal, according to Colts, on the 6 base lenses which they recommend (21% +/- 4%).

    Our abrasive is Colts' 'alundum', though we have not always used this.

    Our testing equipment is also from Colts, but is over 10 years old. I must admit that there has never been any maintenance carried out on this, although we do check the time taken for 600 cycles (4 minutes) and the haze change on the standard lenses. In addition we always check that the unit is level by making sure that we get a Bayer Ratio close to 1.0 for two standard CR39 lenses.

    If we take the haze change on the coated (test) lens to be a more linear indicator of 'abrasive resistance' than just the Bayer Ratio itself, then we can see that the apparent loss in 'abrasive resistance' is nothing like so marked. However, we are sure that there has been a significant change over the last few months.

    I should also mention that we have no humidity control where the lenses are tested, and we have seen dips in Bayer Ratios over the summer months before (presumably because the air is 'wetter' than the colder air in the winter. We have tried drying the abrasive in an oven, but with no clear advantage so far.

    Would you recommend that we try oiling our Bayer Tester mechanism?

    Best Regards,

    Falstaff

  4. #4
    OptiBoard Professional Mauro.Airoldi's Avatar
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    we use an oscillating macchian sold by SCL but the abrasive as I buy from Saint Goben (Alundum ZF12 Grit code 69014135780 cheaply and the same origin 6 euro / kg). my suggestion is to prepare doses of 500 grams and leave it for one night in a clean room (40-50% humidity) before use it.
    I have found differences in the results between before and after the maintenance of the machine because the movement was more soft.
    In any case, my advice is to work to maintain the value of Haze on CR39 after the test, if you were 20% you have to continue to have that value (+/- 2%), on base 5 we had 16%.
    let me know
    Mauro

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    Okay, Thanks Mauro. We will try this.

    Falstaff.

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