Surfacing Troubleshooting

[IChen]

Hi! New participant in the OptiBoard community, I would like to give my greetings and also present to you problems I am having with setting up our surfacing lab. Below I've listed the equipment and materials we are currently using as well as pictures of a couple of our problems;

Blocker - Optek Unity Max Blocker (Wax)
Generator - Optek SL Profile
Finer/Polisher - Optek 425 Surfacer
Lens - Sola PolyCarb SFSV 74mm 6.25base
Lap - Plastic
Water and Polish is chilled to 60°F
Surfacing Process - 2 step - 1st Step - PSI P280, high speed for 1 minute @ 19.8psi
2nd Step - 15um Orange Strip (Optifilm/Durafilm), high speed for 2 minutes @ 19.8psi
Polish - Clearly Digital (3300G from PSI) + Maize HD Polish Pad from PSI, high speed for 6 minutes @ 19.8psi



In this picture, there are these very small scratches visible in the reflection, what causes these? Increasing fining time/pressure and/or increasing polishing time/pressure did nothing. Would this be an acceptable lens?

And another concern is that we still have some fining marks (scratches) on the very outer perimeter of the lens, about 1/6th of an inch in, visible when checking with our Bulbtronic. These scratches only went away when we increased our polishing time to 10 minutes. However, 10 minutes polishing time is hardly acceptable so we would like to reduce that.

And finally, if you look closely at the reflection on the lens, you can make out the outline of a fining pad. Are we at too high of a pressure or are there any other reasons to see something like this?


If you would like any additional information, please let me know and I will post it as soon as I can.

Thank you for your time and any assistance would be greatly appreciated!

[Wes]

Are you using recycled water or fresh?
if that head pressure or machine pressure?
Does the generator give a relatively smooth finish?

[IChen]

I am using recycled water, filtered through a coarse mesh and a pantyhose.

The pressure I gave (19.8psi) is the head pressure, the machine pressure is 50psi.

The generator, in my opinion, gives a relatively smooth finish.



Sorry about the picture quality! Hopefully it does show a little bit of the finish the generator is providing.
This is a CR-39 lens, unfortunately I do not have any generated polycarbonate at the moment, but the finish is pretty close with the exception of the center nub is larger in polycarbonate lenses.

[Wes]

My first thought is that the water is contaminated. Second thought is maybe the polish is, but the fact that ten minutes of polishing gets rid of the issue indicates it's the water. Is this a new problem or an ongoing one? Try changing the water and check your filtration.

[IChen]

I believe you are addressing the 2nd issue I am having? The one about fining marks on the perimeter of the lens? This is an ongoing issue, we've changed the water and we still have the issue. The filtration system (coarse mesh + pantyhose) is the same setup for both our water and polish. I've checked both the mesh and the pantyhose and I am not seeing any coarse particles or chunks caught inside.

[Wes]

Its hard to make a good call based on grainy internet pictures. If your generator is off axis, or the cutter is slightly off center, it can leave small areas on the edges that don't easily fine out. This also leads to more wear on fining pads. Worn pads can lead to debris in the water.
Does this happen with spherical jobs and clean water?

[IChen]

Yes, this does occur with spherical jobs and clean water. We've also tried to check to see if our generator was off by coloring in a lens with sharpie and fining for 10 seconds, there were a couple of spots where the sharpie faintly remained but they were about a 1/2 inch in from the perimeter of the lens while the scratches we're finding are in the very extreme ~1/6 inch.

[RT]

Does your generator support cribbing? The lenses pictured do not appear to be cribbed. That will almost certainly improve issues near the perimeter of the lens.

[IChen]

Yes my generator does support cribbing, and you are correct the lenses are not cribbed. We only have the PCD cutter (Optek 8300-348) that came with the generator so we do not have a fluted cutter. We have already ordered one and eagerly await its arrival. I suspect the cribbing will indeed improve or eliminate the issues near the perimeter of the lens, but what about the other two issues I am having?

[fjpod]

I have virtually the same setup. We crib lenses first on an old Optronics 3...it's just easier. Cribbing is important.

Let me ask a stupid question about those hairline scratches...Are you rubbing the poly lens after polishing and rinsing it? those marks look more like someone took a towel to the lens to dry it off.

[IChen]

I'm not rubbing the poly lenses after polishing and rinsing it, I can't say what our techs are doing but they shouldn't be. All the lenses I'm taking into consideration at the moment are ones I've personally handled though. We dry/clean our lenses with kimwipes (delicate task wipers, http://www.amazon.com/Kimberly-Clark.../dp/B00006IAUT) and 99.9% IPA. I suspect those hairline scratches to be coming from the fining or polishing process since as you can see in the picture, they are in a circular pattern. I would imagine if it was handling or a towel causing the scratches, the scratches would be more linear? I'm just really puzzled by this issue as we've swapped several different polishes and we consistently see this issue, though at varying intensities (amount of hairline scratches).

[WFruit]

Pardon if these questions seem basic or elementary, but I prefer not to assume anything in situations like this.

I'm not as familar with those finers/polishers but others that I've used over the years usually run ~18 psi.

Since these are poly lenses, do you still see the scratches after they have been backside coated?

Is it possible you're getting debris from somewhere onto the pads (probably polish)? Do you start the cycle with the pads wet or dry? Wet not only helps start the process a little more smoothly, but can rinse off any debris on the pads.

Have you contacted PSI to see if they have any recommendations? You're using a lot of their products so they may have tips you can try.

Are you rinsing/drying the lenses between fining and polishing to make sure the lenses are fined out completely? This may help determine if the issue is fining or polishing specific.

For the edge fining marks, cribbing will defintely help, as it sounds like the lens is flexing in the generator. Or it could be your tools are old. You said they are plastic tools, how old are they, and are you sure of their accuracy?

Oh, and welcome to Optiboard.

[fjpod]

What about your fining? Fining a little longer will probably get rid of those edge marks...but it may affect your center thickness, so watch out. Also, your blade may be cutting a tad flat. Have you done a 7 second test? IOW, generate a lens with a -6.00 curve. with a black sharpie draw four or five spoke like lines through the center of the lens. then fine it for 7 seconds on a 6 lap tool. The black lines should wear out somewhat equally in the center as well as the periphery. If not, or iif the periphery is not wearing, then you need to adjust your blade radius calibration.

Im not familiar with the second fine pad you mention. We use the PSI black first fine, and brown second.

[braheem24]

what size are your laps in diameter? ...and do the fining petals cover the lap fully?

I would try increasing time on lower speed

2min 1st fine
3min 2nd fine
4 min polish

all on low speed.

[IChen]

Wow, a lot of responses! Thanks for the warm welcome and the help! Sorry about the late replies, I just got home now and am responding as fast as I can.

WFruit:

Since these are poly lenses, do you still see the scratches after they have been backside coated?

I'm not sure if the scratches will be filled in by the coating or not as we are a surfacing lab and will not/cannot coat anything.

Is it possible you're getting debris from somewhere onto the pads (probably polish)? Do you start the cycle with the pads wet or dry? Wet not only helps start the process a little more smoothly, but can rinse off any debris on the pads.

A definite possibility, we're using a coarse mesh and a pantyhose to filter both our water and our polish, and I've checked both filtration systems and neither one has anything that stands out (besides from the usually gunk you catch in the water and the settled polish abrasive from the polish). We start the fining cycle wet by turning on the water before placing the lens on, and same with the polish, we even rub the polish into the pads with our fingers too.

Have you contacted PSI to see if they have any recommendations? You're using a lot of their products so they may have tips you can try.

I've already contacted them a couple times, both times they've given pretty standard condition recommendations (12-18psi @ 1-2 minutes for each step) and then asked me to check my filtration. I've yet to contact them a third time as the last time they just asked me to double check the filtration again.

Are you rinsing/drying the lenses between fining and polishing to make sure the lenses are fined out completely? This may help determine if the issue is fining or polishing specific.

Yes we are rinsing and drying (with a kimwipe and 99.9% IPA) the lenses, after the 1st step we will occasionally see some very faint generator marks (not detectable to touch though [running my fingers over it]), and after the 2nd step we will not see any generator marks detectable with the naked eye.

For the edge fining marks, cribbing will defintely help, as it sounds like the lens is flexing in the generator. Or it could be your tools are old. You said they are plastic tools, how old are they, and are you sure of their accuracy?

Now that you mention it, the tools are pretty well loved, I'm not so sure about their age as we purchased our set used, and therefore am not comfortable in stating their accuracy. In that case I will definitely get one re-trued and test it out.

[IChen]

What about your fining? Fining a little longer will probably get rid of those edge marks...but it may affect your center thickness, so watch out.

This is exactly why I haven't extended the fining time, I feel much more comfortable lengthening the polish time. I will go back and increase the fining time on the 2nd step by 30 seconds and see if that will fix the problem without affecting center thickness too drastically.

Also, your blade may be cutting a tad flat. Have you done a 7 second test? IOW, generate a lens with a -6.00 curve. with a black sharpie draw four or five spoke like lines through the center of the lens. then fine it for 7 seconds on a 6 lap tool. The black lines should wear out somewhat equally in the center as well as the periphery. If not, or iif the periphery is not wearing, then you need to adjust your blade radius calibration.

I've done something similar to a 7 second test where I generate a -6.00 curve and color in the lens with sharpie, and 1st step fine for 10 seconds on a 6 lap. Everything except for 2 very faint sections maybe 1/4" x 1/2" about 1/2" in from the perimeter fined out. This seemed acceptable to me, do you think I should just go ahead and adjust my blade radius calibration (And any recommendations )?

Im not familiar with the second fine pad you mention. We use the PSI black first fine, and brown second.

15 micron 3M Optifilm/Durafilm is advertised as a 1 step for CR-39/hi index or as a 2nd step for polycarbonate. I can take a picture of it when I get back to work tomorrow but its pretty distinct, white-greyish with orange strips.

[IChen]

what size are your laps in diameter? ...and do the fining petals cover the lap fully?

I'm not currently at work at the moment so I cannot say exactly what they are, but I think they are 3.5" as they are larger than my 3" pads. So no, my fining petals do not fully cover the lap. I didn't think it would be an issue as I made sure the stroke of my fining machines did not cause the lens to go over the edge of the lap (Seen dings on the edge of the lap cause scratches when the lens goes over them).

I would try increasing time on lower speed

2min 1st fine
3min 2nd fine
4 min polish

all on low speed.

I'll definitely give that a shot as soon as I can and report back my findings! Thanks for the recommendations! Also just a quick side note, my finers only have 3 settings; high, low, and play dead (kidding about the 3rd one! it only has high or low) so I might consider increasing fining/polish times even more just to see if lower speed eliminates my problems.

[Jubilee]

A few thoughts here:

1) Surfacing poly, but not coating? I was always thought this was part of the surface side if you will. Offices will expect the lens to be coated and ready to edge if ordering "uncuts." Poly will always have some faint scratches/marks due to the nature of the material. A simple wipe off with even a microfiber cloth will leave marks. Btw.. the marks will resemble your cleaning pattern. So if they are being cleaned in a circular patter, the marks will be circular.

2) If you reduce the speed to low, you take off less material over the same period of time compared to high. Think of it more in terms of how many strokes and orbits it makes over the pad. So increasing the length of the finer cycle, but reducing the speed will not affect the thickness much unless you more than double the length of time.

3) I am on the same page as braheem thinking that perhaps by increasing the time and using a low setting should give a smoother surface. Think of it like using sand paper. For a rough fine, hard and fast works great, when you want to create a nice smooth finish, usually slower and deliberate works better.

4) If you still have some marks after trying braheem's you might kick up the polish time by a minute more.

5) I can't believe no one has asked.. but is this only occuring with poly?

6) How many jobs a day are you averaging, and how often do you change the polish? Do you check the baume'?

[IChen]

A few thoughts here:

1) Surfacing poly, but not coating? I was always thought this was part of the surface side if you will. Offices will expect the lens to be coated and ready to edge if ordering "uncuts." Poly will always have some faint scratches/marks due to the nature of the material. A simple wipe off with even a microfiber cloth will leave marks. Btw.. the marks will resemble your cleaning pattern. So if they are being cleaned in a circular patter, the marks will be circular.

After reading this comment, there is now a little bit of doubt in the back of my mind, but I am still about 95% confident that handling/cleaning is not the cause of these hairline scratches. I shall pay even more extreme attention to this the next time we polish a lens to triple check if it truly is our handling.

2) If you reduce the speed to low, you take off less material over the same period of time compared to high. Think of it more in terms of how many strokes and orbits it makes over the pad. So increasing the length of the finer cycle, but reducing the speed will not affect the thickness much unless you more than double the length of time.

3) I am on the same page as braheem thinking that perhaps by increasing the time and using a low setting should give a smoother surface. Think of it like using sand paper. For a rough fine, hard and fast works great, when you want to create a nice smooth finish, usually slower and deliberate works better.

4) If you still have some marks after trying braheem's you might kick up the polish time by a minute more.

Okay I'll try this recommendation first before I mess with anything else! Thanks!

5) I can't believe no one has asked.. but is this only occuring with poly?

Well, can you believe I didn't think about including my results on CR? We currently only work with poly and CR39, and looking back it just makes me feel even stupider for not including the results for CR as well. Anyways, I'm not currently at work and it is a bit too late to call my colleagues and ask about it, but from what I roughly remember it is also occurring on CR as well. Please let me double check this, as I have a feeling it is pretty important and I tend to doubt my memory when it comes to remembering things.

6) How many jobs a day are you averaging, and how often do you change the polish? Do you check the baume'?

We've still trying to get the lab set up (about 2 weeks now), but I think we average about 10 - 15 jobs a day. We're still trying to nail down the process, conditions and consumables, so we probably change the polish every 5 jobs (suspecting the polish so cycling through them to see if we can find one that eliminates our issues). We currently do not check the Baumé due to us changing polish so much and also since we're cycling through polish, I rigged the polisher to only use a little less than a liter (33.8oz) of polish.

[fjpod]

You should remove all generator marks with the first fine. Do not proceed to second fine unless all marks are gone.

[Jubilee]

hmm. And with the liter of polish, is flow always a nice steady amount? I would hope that it isn't so contaminated after 5 jobs that it would produce results like this. I seriously doubt it with the use of the makeshift filter.

I know that you aren't able to crib right now, though the fluted cutter is on its way. For now, are you at least touching off the lens on the handstone to give it a nice bevel edge to reduce swarf/crumbling, and to remove part of the lip to allow water/polish to get under the lens and more on the pad?

[IChen]

Ha! Combined two responses into one! Getting smarter!

You should remove all generator marks with the first fine. Do not proceed to second fine unless all marks are gone.

The vast majority of the time, I would say about 95% of the time, all generator marks are gone (not visibly detectable with the naked eye) by the first fine, and the 5% that it's not, you can barely see, cannot feel it, and it is not there after the second fine. I wanted to idiot proof my process by just having anyone in the lab able to use the cylinder machines and just fine the lens for whatever the machine is set to but it's starting to look like a pipe dream, especially if I can't get around these issues.

hmm. And with the liter of polish, is flow always a nice steady amount? I would hope that it isn't so contaminated after 5 jobs that it would produce results like this. I seriously doubt it with the use of the makeshift filter.

Ah, I figured someone would ask about that, but didn't include that in my last response as I seemed to getting kind of wordy. But yes, polish is at a constant flow, so that is definitely not an issue. I don't think it is contaminated as when we swap polishes I always have someone check the filtration (mesh and pantyhose) for anything strange beside the usual settled polish gunk.

Also a quick question, I was under the impression that tying a pantyhose was a pretty typical quick/effective way to filter your water and polish, was I wrong? I do have some other filtration media of various sizes (255μm, 185μm, 125μm, 100μm, 75μm, 55μm, 25μm, 10μm, and 5μm) available, I just wasn't sure if that was necessary as the typical size of most polishes is 1.3 microns with a range of maybe up to 6 microns (and up to 13 microns for cheaper polishes). I also didn't want to be filtering too small and end up plugging my recirculation system and having to constantly clean my filter, if it plugs up quickly in my system of 1 liter, I'm scared to imagine what would happen once I go back to a gallon or more. But I'm definitely willing to experiment at this point, solving the three issues I've listed in this thread is my top priority, I can optimize my process later once I've eliminated my issues. Should I be changing my filter to something else? And what would you recommend?

I know that you aren't able to crib right now, though the fluted cutter is on its way. For now, are you at least touching off the lens on the handstone to give it a nice bevel edge to reduce swarf/crumbling, and to remove part of the lip to allow water/polish to get under the lens and more on the pad?

Uh, no I'm not touching off the lens on a handstone . It's partly due to not having one, but mostly due to me not even thinking about it, sorry. This will be the 1st thing I try when I get into the lab!

Seems like I got wordy again, sorry about that! Thank you for all the responses, I'll get to work on your suggestions and report back with my results as soon as possible!

[WFruit]

Unless your generator is putting a safety bevel on the lenses (which it sounds like it isn't), then you MUST touch them off by hand. Not only will you not cut your hands, but you won't tear up your fining/polishing pads, AND it allows the water/polish to flow under the lens.

I'm with Jubilee in being shocked you don't backside coat poly!

I've used pantyhose to filter polish, though I've had fresh water in every lab I've worked in (retail and wholesale). The last place I had to worry about it was at a retail chain location lab. I did 100~150 surface jobs a week there and changed the polish and pantyhose about 1/week.

Silly question about the polish, but are you stirring it on a regular basis? Running so few jobs I'd give it a quick stir before each one, just to make sure the polish particles haven't settled too much. Otherwise you're pretty much polishing with white water...

First fine should completely remove the generator marks EVERY time. One the ones where it isn't, I'd be curious to know, after fining and polishing, if the lenses were still on power. That sounds to me like the lap curves may be worn. Try to keep an eye on which tools give which results.

[IChen]

Unless your generator is putting a safety bevel on the lenses (which it sounds like it isn't), then you MUST touch them off by hand. Not only will you not cut your hands, but you won't tear up your fining/polishing pads, AND it allows the water/polish to flow under the lens.

No we're not putting a safety bevel on the lenses, I was under the impression the bevel and/or cribbing was mainly to improve fining/polishing quality by allowing more water/polish to flow under the lenses as well as less surface area to work with. Do you put the safety bevel on the lenses as well crib? or is it one or the other?

I'm with Jubilee in being shocked you don't backside coat poly!

I've used pantyhose to filter polish, though I've had fresh water in every lab I've worked in (retail and wholesale). The last place I had to worry about it was at a retail chain location lab. I did 100~150 surface jobs a week there and changed the polish and pantyhose about 1/week.

It shouldn't be too much of an issue to hook water into our machine and have fresh water rather than recirculated, I'll go ahead and work on that and see what happens.

Silly question about the polish, but are you stirring it on a regular basis? Running so few jobs I'd give it a quick stir before each one, just to make sure the polish particles haven't settled too much. Otherwise you're pretty much polishing with white water...

Yes, we just stick a tongue depressor in there and stir it up before every job we polish.

First fine should completely remove the generator marks EVERY time. One the ones where it isn't, I'd be curious to know, after fining and polishing, if the lenses were still on power. That sounds to me like the lap curves may be worn. Try to keep an eye on which tools give which results.

I'll have to look into this and get back to you, but the laps I were working with were 6's, which really bothers me since it wasn't something more extreme like a 2 - 3 or a 11 - 12.

[Darryl Meister]

This may have already been mentioned in one of the above posts, and I apologize in advance if this post is redundant, but you may be able to tell the source of the "scratches" by inspecting the actual pattern and texture of the scratches.

Generator marks that have not completely fined out will have a more consistent pattern (spirals for a 3-axis generator, parallel curves for a 2-axis generator) and are more "sleek." Random and more jagged scratches or "swirls" would be more indicative of contaminated water or slurry during fining or polishing.

If you haven't already done this, inspecting the lens surface carefully under an arc lamp or in a shadow box between each step of the process might also help you isolate the source of the scratches. And, of course, obvious issues, such as tears in polishing pads.

I have seen several very good recommendations above regarding cribbing and chamfering the lens blank to improve water and slurry flow. Remember that over-polishing to work around this issue, in addition to reducing throughput, can lead to other unwanted problems, such as waves and polishing burn.

Best regards,
Darryl