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Edging chatter is a visible defect on the perimeter of a spectacle lens characterized by small, repetitive ridges or waves. This defect occurs during the automated edging process when the grinding wheel vibrates against the lens material.
read more about eyeglass lens edging chatter ...The main cause is high-frequency vibration or mechanical instability in the edging machine. If the lens is not securely clamped or if the machine's spindle or wheel motor vibrates, the wheel bounces slightly as it cuts, leaving a repetitive, rippled pattern on the lens edge.
Chatter affects frame fit by creating an uneven circumference. While the defect is tiny, the rippled edge may not sit perfectly flat in the frame groove, which can make the final assembly loose or increase pressure points on the lens, leading to potential cracking.
Technicians prevent chatter by ensuring the edging equipment is properly maintained and calibrated. Important steps include securely mounting the lens with a fresh blocking pad and using the correct cutting pressure and speed for the lens material.
Chatter marks are best identified under magnification. Correction requires the technician to re-edge the lens using a slower speed or reduced pressure, or by using a new, balanced grinding wheel. If the chatter is severe, the lens may need to be entirely replaced.
Yes, chatter is visible on the edge of the lens and can sometimes be felt as roughness.
No, chatter is confined to the very perimeter of the lens and does not affect the clear central viewing area.
Yes, the uneven pressure points caused by a chattered edge can sometimes lead to a stress crack when the lens is mounted.
Edging "chatter" (waves on the lens edge) is a sign of a vibrating edger blade in the lab. If your lenses have a rough, "toothed" edge, they are at a higher risk of cracking under the pressure of a metal frame. Return them for a remake to ensure long-term lens durability.
The Vision Council. Laboratory Safety and Quality (thevisioncouncil.org). 2024.
Review of Optometry. Quality Control in the Optical Lab (reviewofoptometry.com). 2024.
ABDO. Glazing Techniques (abdo.org.uk). 2023.
Optical Journal. Manual vs Automated Finishing (opticaljournal.com). 2024.