Edging Today's Lenses
Welcome to our continuing series of Credit Educations Courses for Opticians.
This course has been approved for one hour of credit by the American Board of Opticianry. No fee is required for ABO credit.
Learning Outcomes: At the conclusion of this credit education course, participants should be able to:
1. Understand features and benefits of automatic edging and drilling technology.
2. Be able to make product purchasing decisions.
3. Perform the techniques to edge current lens materials.
4. Know the details and successfully execute edging of super hydrophobic oleophobic lenses.
Test procedures: Read the article and then click on the "Take The Test" button at the bottom of the page. This will open a new window with a test consisting of 20 questions. To receive ABO continuing education credit, respondents must correctly answer 16 of 20 test questions. Simply click on the best answer for each question and click the submit button at the end of the test. Your test answers will be automatically sent to Seiko Optical and we will send your CEC or notify you of test failure within 7 to 10 business days.
Note: Some states do not accept home study courses for continuing education credit. Check with the licensing board in your state to see if this course qualifies.
Edging Today's Lenses: How to get an edge on processing today's sophisticated lens materials and coatings
There's so much to know and do today to keep up on current lens materials and proper lens processing. Lenses and the equipment that edges lenses can be basic to sophisticated, so the knowledge range has to cover simple to high tech. While that creates an ongoing challenge, it also ensures that being a part of the optical industry is never boring! This credit education course will review a wide range of lens processing equipment capabilities, including how to expertly edge today's top lens materials and how to tackle the challenge of edging super hydrophobic oleophobic AR lenses.
Automatic Edging
Most of today's edgers are truly do-all, be-all. They're capable of edging all lens materials including glass, high index, polycarbonate, Trivex, and others. Many can also accommodate all lens sizes, including small diameter lenses.
Modern equipment also offers polishing and finishing type options. Bevel options allow operators to choose automatic or customized beveling; the systems can calculate the best lens-to-frame fit and appearance; and automatic pin beveling works with all lens sizes, including small frame sizes.
Grooving capabilities precisely locate grooves even on thin lenses. Operation is accomplished with the touch of a button. Contour readings, also called lens mapping, of both lens surfaces determine lens curve and edge thickness.
Clamping pressure can be selected according to the lens material used. When chucking, operators can select delicate, average, or strong pressure. Selecting the right pressure is especially important when edging the new super hydrophobic oleophobic AR lenses.
Several edgers today feature automatic maintenance function, such as self-calibration, wheel cleaning, and statistic and technical logs. High-tech maintenance functions also allow operators to perform routine maintenance without technical assistance. Operators use a customized toolbar, intuitive icons, color-coded messages, and view large color LCD screens to make operations easy, while having options for monitoring edging stages.
Many equipment manufacturers offer integrated finishing systems with automated operations from start to finish. A tracer, blocker, and automatic patternless edger complete the lens cycle.
Computer-controlled operation, 3-D, 4-D, 6-D and beyond processing, and interface with several communication protocols are a few key features for operating accuracy and ease. Most in-house and even some large-output systems feature a small footprint, making it easy to fit equipment in atypical places, like an extra exam room or even a closet.
Software is an important component in any new edging technology. New software allows for faster cycle times, accuracy, and hones output details and performance. Software updates are a key part of any new equipment operation.
Benefits of automatic edging operation include output consistency and control, reduced lens handling by operators, decreased spoilage or breakage, and higher quality lenses. Since these systems are designed to run automatically, an operator can accomplish other tasks-such as helping customers in the dispensary-in addition to doing lab work, which increases efficiency and decreases manpower needs. Today's edging systems are designed to help make your lab more flexible, efficient, profitable, and easy to run.
Automatic Drilling
More and more companies are incorporating rimless drill-and-slot mount capabilities into their edgers. Benefits of this include functional simplicity and high-quality, beyond-basic results that a technician doesn't have to handle between steps.
Some features to look at in the new category include multiple lens material and coating capabilities; six to 10 hole capability in each lens; automatic slot and hole identification and placement; and hole variation including twin holes, slotting, grooving, hole-and-notch, and stylized holes.
At least one system determines the rimless holes or slots required, displays them on a touch screen, and gives the operator the choice of making adjustments or pressing "command" to drill as displayed. The system also computes eyewire thickness and can auto-set the front lens surface to the front of the frame.
Some systems offer angled drilling set perpendicular to the front surface of the lens, which provides a pleasing appearance in addition to properly aligned frames and lenses. Debris and chatter-free holes allow for quicker, cleaner processing. Processing time can drop by almost as much as half, and quality throughout the job is assured, which is important with today's high-end materials and super-hydrophobic coatings.
Another feature on modern edgers is the ability to create custom-shaped rimless lenses. Lens measurements can be modified on a touch-screen to alter circumference, angles, and other parameters, resulting in custom-shaped rimless lenses.
Edging Super Hydrophobic Oleophobic AR
The benefits that make super hydrophobic oleophobic AR lenses appealing to the marketplace-durability, easy cleanability, and resistance to dirt and oils-also make super hydro AR a challenge to process. Unwanted smudges, fingerprints, and debris slide right off super hydro AR. This is great for lens usage, but hard on lens processing. The most common challenge with edging these lenses is lens slippage resulting in lenses turning off axis and off shape. Most coating companies suggest using a protective edging tape on both sides of the lens for leap pad and block adherence during edging.
Specialized stickers, pads, and coatings: Most large lens manufacturers ship their super hydro AR lenses with the processing stickers required to reduce slippage. Some labs and AR coating facilities will provide stickers upon request. The stickers are placed on both sides of the lens and provide better adherence of the edging pad to the lens, as well as protecting the surfaces of the lens.
At least two major manufacturers apply a special coating over the super hydro coating to help with the edging process. This layer provides the adhesion required to block lenses for edging, grooving, drilling, and retouching. After processing, the special coating is removed according to the manufacturer's directions.
Several optical industry suppliers have developed self-adhesive pads to help keep the edger blocks on super hydro lenses from slipping during processing. These single- or multiple-use pads are applied on the front lens surface and serve as a base for mounting the lenses on the edger. The goal is to provide a solid grip to prevent slippage and turning, while protecting the lens and coating.
Enhanced Equipment: Equipment manufacturers have spearheaded making improvements to their machines to help alleviate the chances of slipping. At least one equipment manufacturer's edgers feature a special roughing process that takes lenses down in steps. By optimizing the roughing process with a special roughing selection, users can follow the instructions of lens coating manufacturers on how to prepare the lenses prior to edging to minimize the chances of slippage.
Equipment Advice: Check with individual equipment manufacturers prior to purchasing any equipment. Be sure to review what lenses you currently edge and what lenses you plan to edge. Make sure that the equipment you buy is not only capable of handling your present needs, but will be able to handle your needs in the future. Look at product details and make certain that processing will be accomplished in the timeframe and with the ease that you require.
Sticker or Pad Application: If applying your own sticker or pad, be sure to press them tightly to the surfaces of the lens. If there are air bubbles, remove them by pressing them out with your fingers. Cut off any part of the sticker or pad that may fall outside the shape of the rim. This will allow re-edging if necessary, as cutting off excess helps prevent the sticker or pad from coming off.
Several manufacturers supply additional adhesive tapes that are compatible with their super hydro coatings. These tapes allow normal leap pads to stick better. These types of tape can be applied to the lenses first or to the leap pad surface for automatic blocking in some machines.
Clamping: Since the clamping pressure of most edgers is often electronically controlled, the equipment is capable of holding the lens at two different pressures during the edging cycle.
One pressure simply holds the lens while it's in the machine, while the other pressure holds the lens during contact with the wheels is higher. This operation allows the machine to hold when it needs to, but not with too much pressure as to cause damage (crazing) to the lens coating during non-edging time.
Some machines have a higher incidence of slippage than others, depending on the lens material and/or coating being edged. One of the first responses from lens manufacturers to equipment manufacturers is to make sure the chuck pressure is set appropriately for their lenses. This often requires the lens manufacturer to contact the equipment manufacturer's technical support group to make the necessary changes and recommendations. If slippage continues, the next response is typically to test different protective stickers until the manufacturer finds one that works best with their product.
Blocking: Use a non-metal finishing block with a base curve that's as close to the base curve of the lens as possible. Many equipment manufacturers now offer blocks made out of softer material than metal blocks. These new blocks better conform to lens curvature and protect the coating from marks that might be left on the lens.
Some equipment manufacturers recommend their own blocking technology, including appropriate cup holders, with the correct patch seals front and back. Other manufacturers recommend using the largest blocks possible to cover a larger surface and boost adherence to the lens. Block the lenses centered on the OC (Optical Center), since decentered blocking increases torque on the blocking pad, which increases the risk of lens slippage. Align the central hole of the protective sticker with the optical center of the lens; place the sticker in the direction furthest away from the finished shape's edges, this is usually horizontally. It's better to re-block the lens if the adhesive sticker, pad, or temporary pad control layer is not within 2mm of the center of the sticker.
Reduced Pressure: Reduce pressure on the roughing wheel until the lens has been roughly shaped. Decrease the pressure against the wheel and/or the feed speed during the roughing cycle. This reduces torque on the blocked lens and helps prevent slippage. In most automatic edgers, do this by adjusting the edging cycle setting to "fragile," "delicate," "soft grind," or even "wine glass."
Polycarbonate requires reducing high torque conditions prevalent during edging to avoid slippage. High torque can cause lenses to warp and coatings to craze, so it's important to use as little torque as possible.
Set the machine on slow speed and diligently monitor the process. Use blocks made of softer material than metal. Indices of 1.60 and 1.67 don't have the high torque conditions prevalent in edging polycarbonate, which makes edging these super hydro coated lenses easier. Check with individual lens manufacturers for the best way to process their lenses, since each manufacturer's coating has different characteristics.
Hydrophobic Oleophobic AR Tips
Here are some general pointers for edging super hydrophobic oleophobic AR lenses. Always check with the lens manufacturer for the correct procedures for their lenses. Not following manufacturer guidelines can cause unexpected removal of the block and/or slippage on the roughing wheel during the edging process.
1. Perform cosmetic inspection on every lens before processing. If the lenses have a pre-applied pad, sticker, or temporary pad control layer, don't remove them. Avoid wetting the lenses, which makes the coating very slippery.
2. If you're applying the sticker or pad yourself, make sure you use a quality pad. Ensure that there are no foreign bodies between the lens surfaces and the stickers or pads to avoid scratching. If the sticker or pad protrudes outside the eye shape, cut off the excess areas to avoid unplanned removal during edging.
3. Handle lenses by the edges only to avoid fingerprints or hand contact with the lens surface.
4. Check to make sure the blocker is dry and clean.
5. Don't touch the block adhesive. Apply the adhesive directly to the block.
6. Select the material option on the machine that applies to the lenses that will be edged. When using a wet edger, adjust the edger so that water doesn't flow directly onto the edges of the sticker or pad.
7. Place the blocked lens in the edger. The block will be placed on the center of the anti-slip sticker, pad, or pad control layer. Make sure not to touch the lens surface during this set-up.
8. When the protective sticker or pad, adhesive blocking pad and finishing block are securely fixed to the lens, begin the edging cycle. Once the cycle is completed, remove the edged lens without touching the lens surface.
9. Verify lens fit before removing the edging block. If the edging block is removed, it can't be reapplied.
10. Re-edge only if the lens is still blocked and water hasn't seeped under the sticker or the pad. Otherwise, de-block, clean, dry, and mark the lens, then block again with fresh stickers or pads.
11. If the lens has a sticker or pad, slowly and carefully remove it by hand. If the lens has a pad control layer, wipe it with a soft cloth for removal. Mild detergent and water may be necessary for complete removal of the pad control layer.
12. When edging rimless drill mount lenses, mark the drilling points with an approved permanent marker.
13. Perform final cosmetic inspection after mounting and cleaning the lenses.
14. To reapply progressive lens markings, locate the progressive engravings and use a recommended marking pen to mark the center of the engraved markings. Apply the appropriate mask to align with the markings.
Remove the mask after fitting the patient. Remove the pen markings using a piece of tape. Apply over the marks and pull off the tape, or gently push it off using a fingernail.
15. Avoid using too much water or placing the lens under stress during processing. Follow the equipment manufacturer's instructions. Keep stickers and pads away from direct sunlight, high temperatures, and moisture.
This concludes the article. Click the button below to take the test.