Recently we have been getting a lot of swirls on every job we run. In your experience what is the most likely culprit?
Recently we have been getting a lot of swirls on every job we run. In your experience what is the most likely culprit?
There a multitude of issues that can cause this problem you have to be systematic in solving it.
1 Is the problem on all machines and all materials
2 is the pressure correct on all fining and polishing machines
3 are you removing the correct amount of material during fining
4Are the curves accurate off the generator
5 Is the Baume correct on the polish
this is just a start if you try all these process issues and still need help repost
Check your finning water temperature. Shoot for 62-65 degrees. My assumption is your using a one step pad. These pads have multiple grits where the bigger particles are to fall off after a period. Cooler temperature degrades this function. Also run your finning water through a filter. If you have used a direct plumbing your water temperature will fall the ambient line temp (55 degrees). The magic in any surfacing environment is temperature control. Any extreme both hot and cold is going to cause process fluctuations. Polish temperatures also have an optimum point for optimal stock removal. Check with the manufacture for best temperature. Polish also gets out of concentration when tool and pads are being used in and out of the production. The pads contain polish and suspension agents so a baume’ make up is not always a solution. Best practice is one gallon of polish will equal X number of lenses. A good chemical manufacture will tell you what X is. Never exceeding that number will go a long way into stabilizing the process and process costs. Hope you find your solution!
After some thought, I would like to walk back my comments. A good start would be to speak with your consumable’s supplier. They will get you all the parameters for the best practices with their supplies. Establish a daily, weekly measurement process that you can use to verify your process is in “control”. Also, it is hard not to cherry pick suppliers on supply prices but when you purchase supplies from multiple vendors all bets are off on quality and results and no one party can be held responsible. Your consumable supplier is one of the best assets any lab/lens maker can have. Consumable suppliers… my bad, forgive my previous comments.
What if anything has changed now that swirls are apparent?
Simply put swirls are the product of the abrasive material on the pad "wearing" off and then the lens is scratching on the paper backer.
I would check on curve accuracy from the generator.
We have found the smoothing pad (pre Polish) is usually the problem and the manufactuer , not the die cutter, has inconsistant batches. Check you lot numbers.Originally Posted by peyes
If fining marks are consistently in center, or near edges, then check generator calibration because curves are slightly too steep / shallow.
If they are all over then check pin pressure and run times on cylinder machines. I have gotten a bad role of fining pads, but it's usually a matter of bad adhesive allowing slippage vs wrong grit.
Polish needs to be at proper temp or it will break down and lose viscosity, so check that the chiller is running properly.
Two things not mentioned here.
Pads. Check
Calibration of all surface equipment. Check
Temperatures. Check.
What LMS? Are the pad comp values correct? Has any updates been pushed by your LMS provider?
This may be the missing link.
I bend light. That is what I do.
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