"Pearls" for Edging
Compiled by the editors of 20/20 and Vision Monday
Finishing premiums lenses can improve a bottom line or wreck it, if spoilage is high. Below are a list of guidelines and common pitfalls to avoid in order to make an in-office finishing lab efficient and effective.
- Inspect all lenses prior to beginning the finishing process. When ordering uncut lenses, make sure the lenses has been fabricated as ordered. If the problem is detected after edging, the wholesale lab is no longer obliged to remake the lens.
Use edging tape on Anti-Reflection lenses. Many dispensers, especially those with patternless edgers, will forego this step on standard lenses without a problem. AR lenses scratch more easily, and using the edging tape will ensure surface protection.
Clean your edger daily, including vacuuming out the grinding chamber, using canned air on PC boards and frame tracing stylus, and wiping down the outside of an edger with a mild soap and rag. If different lens materials are being used on the same edger, clean edger before switching materials.
Before edging AR lenses, make sure the finishing machine is well-cleaned. Dust and particles that would not otherwise affect a lens will damage AR coating. While a finishing machine should be cleaned on a daily basis, an additional cleaning prior to edging AR lenses will decrease the risk of spoilage. If a water coolant is used, change it daily and place a filter on the edger to strain foreign material from the coolant.
When edging AR lenses, protect lenses on both sides with protective edging tape or blocking pads. If using blocking pads, do not leave pads on lenses overnight, or else the lenses can be permanently marked. Remove block carefully and peel edging tape off gently.
Other edging precautions against damaging the AR coating include: Replacing cutting blades on dry edgers frequently (after 50-75 lenses is recommended), setting adjustable-feed rate edgers at the minimum speed, and edging lenses to the exact size in order to avoid putting pressure on the lens when it is mounted in the frame. After an AR lens is edged, rinse before handling to remove grit and other particles.
Polarized lenses require cleaner coolant than other lens types and it is a good idea to change the coolant prior to edging polarized lenses. After edging lenses, debris and swarf accumulates in the coolant, and these particles can weaken the raw edge of the polarized lens, making the laminate crack.
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