coating problems - MR3

[essegn]

It seems that we are facing the same problem like in this thread:

http://www.optiboard.com/forums/showthread.php/42817-Coating-Problem?highlight=uv+coating

We coat the both sides of 1,5 material and after coating we can see some small semi - circles.
We were able to do both side coating without any problems in the past.

When we coat the transparent material or tinted stock lenses we have no problems, but when we coat tinted lenses by ourselves :

lens could be without any semi circles
lens could have small semi circles from one side - most frequent problems
lens could have small semi circles from both sides

The tinted lenses from our production has uniformly color without any defects.

According to attached thread, where is written that exchanging of wash nozzle had helped i tried to do not wash and dry lens - so the first operation was coating and second UV curing - but semi - circles were still visible.

Anyway, the lens after wash + dry operation is dried properly.

We changed air filters, lacquer filters, suction cups, complete new lacquer.
Coating pump is working properly, we are able to adjust the height of the lacquer and the lenses are cured well.

If you have any ideas i would be more than glad

[DragonLensmanWV]

Try tinting the lenses a bit darker than desired, then neutralizing it to get back to the desired color, then clean well and coat. This will remove all tint residue from the process.

[Mauro.Airoldi]

It can be limestone, my suggestion is to colored, rinse immediately in DI water, clean with solvent (alcool or acetone) ad later coat it.

[essegn]

Thank you for replies. Unfortunatelly, none of them helped us.

We made really a lot of tests and i found the following:

Coating of transparent stock material 1.5 – results ok
Coating of transparent stock material 1.6 – results ok
Coating of colored stock lens 1.5 – results ok
Coating of transparent material 1.5 – results ok
Coating of transparent material 1.6 – results ok

Coating of tinted 1.5 material – circles
Coating of tinted 1.6 material – circles (for tinting 1.6 material we use different dyes and different machine like for material 1.5)
Coating of transparent poly – circles (we can see the whole shape of suction cup from the both sides)
Coating of transparent trivex – circles

Could you see any connection between cases where the circles are shown after coating process ? It seems for me, that the softer the material the more problems we have with shown circles. I have already try to set the lower and higher pressure on vaccum cups, but it didn't helped.

[Jeff Trail]

Two things, one being a clarification, are you running the lens wet? spray it with alchohol right before popping it in? ..9 times out of 10 the "circles are going to be water related... you are running a filtration system or DI on the wash side? One thing you can do instead of wasting lens after lens is stop it after the wash cycle and check the lens for and spotting.. it could be the range of motion of your spray/air nozzle and also check and see if your haskell pump is sputtering after the air cycle.. you can check all this right after the wash cycle before it hits the coat bowl.. your dicription does not meet the problems you see(usually) in the coating bowl.. also since it appears to be tied to tint... are you using DI in your tinters and wash up? sounds like mineral splotching to me..

Jeff "mini or MR3.. both can be a pain at times" Trail

[Speed]

Sounds like you may be trying to put coating on top of coating. This can be done, however you must do something to reduce the surface tention. The reason for the variations, (sucess and falures are probably due to different manufacturers. Also, I can't think of any reason you would need to coat a product that is already coated. There are tintable products avalible, and you will be coating the back surface of any lens that you surface.

[Chris Ryser]

circles on UV cure hard coats are often signs of steaming up water during curing cycle. Some lens pores have not fully dried up and develop steam. Try to dry longer the circles might just disappear.

[essegn]

Thank you for all replies.

We coat the only uncoated lenses. I noticed that after wash and dry operation that lenses are not dried at all often, even though i set the air blowing to the maximum.

But when i run the drying cyclus by manually from service menu, i can't see that during the blowing of air any blowing from water nozzle, so i am not sure if it is related to the production cycle.

I will try to change the water nozzle and will see what happen

[essegn]

I have changed the wash nozzle for the new one and the result are the same. I can see that quality of the coated surface (the visible circles) is changing by adusting of parameters (wash, coat spin off, lamp, coating pump...)

Could somebody send me some settings or so?

once happens, that i coat the back side only and circles were visible on the front surface - even thought the surface and suction cups were clean.
Any other ideas will be appreciate.

[Dantech]

You should not adjust those knobs without a laser tachometer, adjusting changes the speeds at which the spindles spin during the cycle. ultra optics will rent you a tachometer for more than they cost new through grainger. Contaminated air is another thing to look at, you can do this by running 99% ipa instead of water and unhooking the air nozzle. How were you adjusting the air pressure to the nozzle?

[essegn]

thank you for reply

Unfortunatelly, i am not sure what do you mean by : Contaminated air is another thing to look at, you can do this by running 99% ipa instead of water and unhooking the air nozzle.

what is running 99% ipa ? For washing cycle we use the alcohol and DI water. I am not sure what do you mean. What is ipa?

We cleaned the HEPA filter(filter on the machine top).
I made one test: i disconnected the washing cycle and air cycle and found the circles on the all lenses..

Normally, the air nozzle is set toward the washing nozzle.(i tried to set it in different ways and i tried the modify the air prezzure during drying process)
The curing cycle is set to 25 seconds and the number of the "beats" during the washing operation is set to 25.

Sometimes i can see the semicircles on the both sides of lens. Sometimes i can see not small semicircles but big circle from the edge diameter of suction cup.

I am able to to reduce or increase the visual performance of semicirles (the number and visibility) on the coated lenses by changinf of parameters (wash, spin coat off ..etc.), but i am not able to reduce it at all. Sometimes i can see the circles by one and sometimes i can hardly to see it under the camera of our TECO-printing machine.

During the one test UV lamp stopped in the middle and was lighting to the lens for +-40seconds. After the lens inspection i have seen the the whole suction cup was visible easily. But decreasing of curing cycle doesn't solve the problem ..

What do you think ?

[Tito]

Hello Peter
I have read your thread,let me make some suggestions;Check that you do not have any air in the laquer pipe lines,the laquer spray nozzle has to shoot perpendicular or 90*if it is off you may get this semicirlces.

[Dantech]

What i meant is, you can take the air and water out of the equation by running 99% isopropyl alcohol instead of water and disconnecting the air jet. However it seems your lamp may be getting stuck mid cyle, I have seen the roller bearings go bad and cause this. You can open the rear doors and bypass the door switch by unhooking the two connectors that go to the sensors and plugging the two lead wires together, then watch the lamp during its cycle. Also like i said get a laser tachometer, we check our rpms every week. Are you having large variations in coating height when priming? Are you running quest coating?