Technical lab question

[Russ in Texas]

I'm definitely not a lab guru and I have a somewhat new guy in the lab that is having problems with our Gerber polisher putting swirls on the lenses. He's tried different pads and new pins but it didn't seem to help. Any other ideas that might help out?

Thanks in advance!
Russ

[cmhargrove]

I'm definitely not a lab guru and I have a somewhat new guy in the lab that is having problems with our Gerber polisher putting swirls on the lenses. He's tried different pads and new pins but it didn't seem to help. Any other ideas that might help out?

Thanks in advance!
Russ

I would ask first if the swirls were all across the lens, or localized in the direction of the lens cylinder axis. However, I'll take a "blind shot."

Three main thoughts:
1. There is usually a belt on a cylinder machine which controls the horizontal movement of the cylinder table. Check under your machine and see if there is a small broken belt.
2. Your "generator" needs to be recalibrated.
3. You are recycling your polish and have accidentally gotten something abrasive in that polish and need to change it.

That's a "blind guess," more descriptive info might help.

[WFruit]

Is it doing it on all materials or only certain ones?

Did the new guy figure he could save some time and shorten the polishing time? Also, make sure he's stirring the polish, especially in the morning or if the machine sets for more than an hour or so to make sure the polish is mixed well. Double check the temperature also (although warm polish usually causes other problems).

Did you change backside coatings? Some are thicker and fill in those swirls. If you went to a "thinner" coating, it might no longer be doing that.

I would definitely recommend changing the polish. I don't know your setup, but I would guess that you have some sort of filter on the polish leaving the polishing chamber before it goes into the resivor. Check that for holes as well.

More info on the generator and polisher might help.

[kelanor]

There may not be a sufficient flow of polish... so it could be a problem with the pump or a clog in one of the lines.

Does he have a filter (knee high) on the equipment?

Also is it all the lenses or is it just one type? Poly vs plastic etc, could mean the problems are coming from somewhere else, like your coater.

Hope this helps, its been a while since I've done any surface work.

[Russ in Texas]

My lab guy got sick and had to go home early today so I'll have to wait until he gets back (hopefully tomorrow) to ask him for answers on these good questions. I'll post more info tomorrow if he's feeling better and makes it back. Thanks for your help!

Russ

[DragonLensmanWV]

Ah! That's the problem - barf in the polish!:D:D

If nothing has changed and now there's swirls, it does sound like debris in the polish. Check to see if they are random (debris) or like a spirograph tube pattern (wrinkled fining pad).

[k12311997]

is the fining two step? Maybee the second fine is not long enough? not enough pressure on the polisher?

[albednar]

There could be a number of variables that need to be addressed. Are you seeing this on all materials or is it material specific such as polycarbonate. Everything you do leading up to the polishing process will affect the outcome. Proper generator curves that match the tool curve required. Fining times, speeds, pressures, water temperature and specific pads to prepare the surface properly for polishing.

As noted in previous comments, the same rules apply in polishing, times, speed, pressure, baume, temperature, age of polish and a high quality velveteen.

I have a number of articles available on process control and surface calibration that I would be happy to share or I would be happy to talk with you via phone.

[Jubilee]

depending on how old the equipment is...

Strokes and orbits? Is the polisher moving the lens in accordance with the laps to get the whole lens polished?

Axis?

Got a model number for us?

Also if you can let us know what materials, lens styles, etc you are seeing this on that can help..

[rcroutch]

Are you sure it's comming from the polish cycle, dirty or non filtered water from the finning cycle could leave too deep of swirls to polish out.

[YrahG]

Here are a few culprits in no particular order:

• Debris in the polish
• Generator curves need calibrations
• Pads are not aggressive enough for material
• Unevenly applied pad
• Cycles (fining) not long enough
• Pin pressures too low
• Material settings on generator need adjustment

Your question seems to be specific towards the polisher putting swirls so it's more than likely debris in the polish. If you meant the fining process then I would check the curves coming out of the generator first, then check the pressures and cycle times if these are right make sure the pads are proper grit for the materials you are fining (it seems like you've already done this).

DragonlensmanWV brings up a good point with the pattern of the swrils are they circular or spirograph. Circular means that the lens isn't being fined properly which could be curve, timing, or pressure. Spirograph means that it is debris or a lump in your pad.

[scriptfiller]

Make sure the fining water is clean and that each step (if a two step process) is ran for the correct amount of time.

Make sure the baume of the polish is proper or change-out polish on a set interval based upon production levels.

If the swirls are the light variety, they are almost a result of fouled fluids.

[Russ in Texas]

Thanks for all the responses, I'm saving this thread in case we have another issue like this I'll have some ideas to work with. And no DragonLensman, I verified he didn't barf in the polish but that was a good thought, lol.

My lab guy is now running it twice and it gets the swirls out so I'm thinking he's using the wrong pad or maybe it's the pin pressure? We're running a 16 on pressure and I heard it's supposed to be more like 18?

He also says he's using a pad made for CR-39 but we use to run an all-purpose pad and I don't remember ever having this problem on multiple lenses. I guess it's not a polish solution related problem or running it twice would just make more swirls right?

BTW, it's an Acuity polisher about 5 years old.

Thanks!
Russ

[DragonLensmanWV]

Thanks for all the responses, I'm saving this thread in case we have another issue like this I'll have some ideas to work with. And no DragonLensman, I verified he didn't barf in the polish but that was a good thought, lol.

My lab guy is now running it twice and it gets the swirls out so I'm thinking he's using the wrong pad or maybe it's the pin pressure? We're running a 16 on pressure and I heard it's supposed to be more like 18?

He also says he's using a pad made for CR-39 but we use to run an all-purpose pad and I don't remember ever having this problem on multiple lenses. I guess it's not a polish solution related problem or running it twice would just make more swirls right?

BTW, it's an Acuity polisher about 5 years old.

Thanks!
Russ

Well, if he's using a pad made for CR-39 on poly or Trivex, as Jamie Hyneman says, "Well right there's your problem."
CR-39 pads will not remove enough stock in one cycle and will gum up if you use them on poly. Otherwise, it sounds like your curves from the generator are off. Are the swirls in the center or around the edge?

[scriptfiller]

What Dragon said, gotta use those aggressive poly pads for first fine on poly.

[WFruit]

Instead of running it twice, why not just lengthen the Polishing time?

If everything else checks out with all the other fining pads (and that is definitely something to look at), I'm willing to bet that the fining time you need is more than what you're currently doing, but less than 2x what you are running. Test lenses are your (or your lab tech's) friend.