TechTalk Jan/Feb 2016

By Staff

ELIMINATE KNIFE-EDGE LENSES WITH A SOFTWARE FIX

Digital surfacing presents a number of challenges to both labs and those writing software for them.  A good example is soft-tool polishing and the complications created by knife-edge lenses.  Roughly 25 percent of surfaced lenses develop knife edges inside the circular crib radius because of plus power and cylinder. These sharp edges rip polishing pads and can cause breakage on that lens and any other lens using the damaged pad before the problem is discovered.  Labs have had to manage this problem by taking the lenses to a hand stone before polishing, potentially beveling away a useable portion of the lens. DVI has developed innovative methods to utilize digital surfacing techniques and equipment that can eliminate knife-edge lenses.  One method is to pass a complex cribbing shape to the generator that will crib along the knife edges of the surfaced lens while staying outside the frame shape. This effectively automates and optimizes the manual hand stone process. To correctly define the shape of the knife edge, complex cribbing requires extremely accurate lens profiles. DVI software can perform this crib calculation for any lens style, whether digital or toric. Another way to eliminate knife-edged lenses is to create a rear lens surface where the curvature outside the frame shape changes to follow the front curve of the lens. DVI calls this "Digital Fill" and uses it to eliminate thin points that would become knife edges. Digital Fill also benefits the AR coating process by delivering round, full-blank lenses ideal for coating racks. This patented technology is being tested at a number of labs running DVI software. Knife-edge lenses are yet another example of how challenges created by developments in lab technology can be solved with innovative software solutions.   Dan Lundberg, software consultant, Digital Vision, Inc.

Stop Wacking!

Surface lens deblocking has long been a sore spot in the lab.  Usually you’ll find elegant machinery performing sophisticated processes to produce beautiful digital lenses—only to hear the familiar “whack” needed to remove the lens from the block.  Manual deblocking and tape stripping can account for up to 20 percent of surface spoilage, including fractures, chipped edges and scratches.  Operators experience repetitive motion and are often at risk of hurting themselves and your lenses. In addition, the process involves at least four manual steps—deblock, tape removal, alloy reclaim and block cleaning.  A lot of manual labor and a lot of space are dedicated to all the deblocking steps.

 Schneider’s new DBA and TSA Modulo eliminate this non value-added, labor intensive process.  Using a warm water jet and smart nozzle design, the DBA removes the block and alloy while reducing alloy loss by up to 60 percent. This can mean real savings in consumables along with higher yields. All alloy is removed from the lens, tape and blocks.  The clean block pieces are ready for immediate re-use.  The TSA quickly removes the tape and further rinses the lenses. It easily handles even the sharpest of knife edges. In additional to all the other benefits and a reduction in spoilage, using the DBA and TSA mean radically reduced manual handling of alloy as well.  It’s centralized and automated. Both units have a high capacity of up to 100 jobs per hour.  Lenses are handled gently with no impact on the surface.  Centralized reclaim, no repetitive motion, no scratches or lens damage, no whacking.  Kurt Atchison, president, Schneider Optical Machines.

 

DO TWICE AS MUCH WITH ONE POLISHER

As with most businesses, labs are continually challenged to do more with less. In order to stay competitive they must be able to continue to increase output without expanding their facilities or labor force. Current advances in digital technology, such as Satisloh’s new Multi-FLEX polisher, are enabling labs to do just that.  By providing more than double the output of two machines in the footprint only slightly larger than a single machine, the Multi-FLEX allows labs to maximize their production floor space. A simple, robust automation system reduces maintenance requirements and maximizes uptime. Adapted from the semiconductor industry, the simplified loading system handles only lenses, no tools. Operating only in two axes it reaches all positions with reliable, precise and fast movements. Positioned above the polishing chambers, the gantry loader doesn’t obstruct the view and provides free access for maintenance and adjustments. A suction cup handles the lenses before and a four-finger gripper after the process without touching the polished surface eliminating scratched surfaces. Once processed, the lenses are rinsed and dried in a separate parallel washing station leaving them clean, dry and inspection-ready. Designed for high-volume production lines with diverse production needs, the Multi-FLEX has multiple options for a mix of lens characteristics distinguishing this polishing system. Using only a single tool geometry for all standard materials and curvatures and is engineered with three independent polishing chambers, each with two spindles, providing unrivaled production levels and process flexibility. The long-lasting single tool helps optimize production flow with fewer tool changes and reduces polishing tool inventory and complexity.  Ian Gregg, director of surfacing products, Satisloh

 

 

 

 


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