Marks on AR

[bt5050]

hi everyone -


just wondering - although i have not been working in a lab for a long long - a good friend of mine - just got hired ( with in the past year ) - in one of those retail labs

anyways - i guess they are having issues with 1.0 mm poly ar - getting those chuck marks - i had emailed the postings here - however - he was saying that the get cmmissions and they are compensated based off of breakages -

My ? would be - if they are doing everything - you guys talked about - and the lens still crazes - would you guys look at that as a breakage - or a defective product - ? ( Becuause the coating did not hold up ) - i guess they see more on smaller frames - and also more square frames - then round - ( not sure why that is ? ) - but i was told they follow all the steps essilor told them - such as fragile chuck - flat blocks - lens protectors - and careful deblocking - new edger wheels - but reguardless - some jobs just keep getting them -

I HAVE NO CLUE why they need to make a 1.0 on a -25 or even a -1.50---- ? when i used to edge - i would see that they would even them out - and make the LOW powers a bit thicker - and they seemed to stay in the frames better - and also not have any of these issues - he talks about - ? I think they are taling about alize product line ? not exactly sure - but why make the entire LINE OF POWERS 1.0 MM ??

Just curious - about your thoughts - and experiance - with this - since i have no clue -

[For-Life]

Could be a defective coating. Let me just go over a few things to ensure we have everything covered.

- Double pad the lens by placing a pad on each side
- Use lower pressure
- if it is a dry edger ensure the blades are sharp
- Match the other side of the pressure with the chuck side. We are all aware of what side the chuck goes on, and then the other side closes with the plastic holder. Make sure the other plastic side equals the diameter of the chuck. Why? Well if one side has a larger diameter of the other there will be pressure made against each other. This is relatively an unknown procedure.

- Slowly twist the chuck off the lens and try to get it so that the check seperates from the leap pad, and not the chuck and leap pad seperating from the lens.

- Use thicker leap pads

Hope this helps

[bt5050]

they always used to double pad - however i was informed that essilor rep told them not to - that there is no benifit - and actually does more harm then good - ? NOW WHY I HAVE NO CLUE = we always used to - but i could not tell 100 % it always helped

When i was edging we used the kappa - and i found - that by hand cribbing those larger (( lower power lenses )) - it really helped -
i just blocked it - and semi - traced the demo - and took the blank down on our spartan ruff wheel ( was able to operate by having the door being opened during cycling -
by do this - and getting the lens to ruffly the correct shape and size - it did not bow or flex the lens - such as it would if you took it and started it large out of the package -
seemed to work on those jobs that would always get a mark -
it is very clear - that when u had these thin lenses - and watched it hit the wheel - you would see it flex - until it got closer to size and shape -

anyways - i had also had the same thoughts - that if they did everything they where supposed to - and it still got marks - to take them as a defect - since it wa not a operator error - just a flaw in the lens design -

DO U have any thought why they would do the entire line 1.0 mm - and not thicken those LOW power lenses - ? IT is clear that there is no benifit of havign a 1.0mm --- -.25 shp -----

I can not figure out why - they woudl not make those low powers 1.5 or even 1.8 mm like they used to ?
must be - so they could sell more - on all these that gets edger marks !!

Thanks again
b

[MarcE]

In most places a 1.0CT is an upgrade. They sell it because the pt bought it. Even if they didn't need it.

Now you know why the labs say that that a 1.0CT isn't always possible. Poly is soft. I have seen this on some lenses that are too new. I.e. they haven't sat one the rack for more than a week or two and are not fully cured. I believe that Essilor and Hoya (and maybe others) uses a "cushion coat" for their "Ultra-lite syle" 1.0CT lenses that helps prevent this problem. If they are doing their own coating, well there is part of the problem, they may need a special hard-coating for 1.0CT.

Just rambling. I don't have a solution, just conveying what I have heard and read.

[Pete Hanlin]

If the lens is flexing, either the feed rate is too high or the cutting surface is dull. Most edgers have a "fragile" setting for thin AR coated lenses (which I call "thARCles" :^).

For-Life is absolutely correct, to avoid most of the crazing marks (that's what the marks are, micro-crazing from flexure), make sure you:
1.) match the sizes on both sides of the chuck,
2.) use minumum clamping pressure
3.) use fragile setting if so equipped
4.) maintain sharp cutting surfaces
5.) twist the block off- not peel

When these steps are followed, double padding has not been shown to solve the problem. Sometimes it even exacerbates it (because the lens can flex more with the extra "cushioning" of the pads).

[Cherry Optical]

1.) match the sizes on both sides of the chuck,
2.) use minumum clamping pressure
3.) use fragile setting if so equipped
4.) maintain sharp cutting surfaces
5.) twist the block off- not peel

Old thread but a resurfacing problem.

What do you do if you are following all of these procedures and still having a problem? Anyone have any other tips or ideas that have worked for them?

Would using another AR coating eliminate the problem? The pattern is rather well established at Cherry Optical: Poly w/ Alize are the only lenses that we see this problem on.

Adam

[Lee Prewitt]

Adam,

[quote]Would using another AR coating eliminate the problem? The pattern is rather well established at Cherry Optical: Poly w/ Alize are the only lenses that we see this problem on. [quote]


You are right that this is a recurring issue. I get asked this question all the time "Does your poly AR crack?" and fortunately I can say that at iCoat, we do not have issues with our poly lenses or any of our coatings. Perhaps it is time to talk??

[Cherry Optical]

Adam,

Perhaps it is time to talk??

Lee,

Good to hear things are going well at iCoat. Only problem I see there is that I can drive 3 miles down the road to Global to pickup finished stock poly lenses with Alize' on them. If I started custom grinding lenses and sending them for AR the phone would be rining off the hook... "Where's my job? It's only SV PC AR, ya know!?!" :)

E-mail me at adamcherry@cherryopticalinc.com if you have any other ideas.

Adam

[Lee Prewitt]

Lee,

Good to hear things are going well at iCoat. Only problem I see there is that I can drive 3 miles down the road to Global to pickup finished stock poly lenses with Alize' on them. If I started custom grinding lenses and sending them for AR the phone would be rining off the hook... "Where's my job? It's only SV PC AR, ya know!?!" :)

E-mail me at adamcherry@cherryopticalinc.com if you have any other ideas.

Adam

I can send you stock poly (Optima) with Stainless to you and you won't have to drive anywhere ;)