Eyeglasses Frame Production

Written by Optician Club on . Posted in Eyeglasses Frames, Optician Tools

1. Organize eyeglasses frame production lines. Develop the tools and jigs as well as any molds and dies necessary for production.

2. Identify machinery needs. They may be any variety of CNC, laser, injection molding machines, etc.

3. Metal frame production begins with cutting the rim wires. This requires extreme precision, which often differentiates one factory from another. The quality of a factory can often be judged by their eyewire cutting processes. Remember, production from one order must be identical on all subsequent orders. This ensures that the ECP and their lab's experience is consistent from order to order.

Eyeglasses Frame Production

Eyewires are soldered to endpieces and the bridge, while temples are being machined and hinges are being attached. The metal frames are tumbled and hand polished for a smooth finish before going to plating and/or being subjected to other coloring techniques. The quality of coloring is affected by the quality of the frame's surface. A base is applied by electroplating, usually in gold, silver or a shade of gunmetal. The frame may then be coated with a color spray paint. The best quality paints for eyewear come from Switzerland.

Titanium frames are more expensive for several reasons. The raw material is more expensive, but the larger cost difference is due to its fabrication requirements. Titanium is extremely hard, requiring huge presses to stamp any impression into the material. Special welding equipment is used for titanium, as opposed to soldering equipment used for other metals. Coloring titanium is not always simple either since colors adhere differently to this material requiring special techniques.

Beta titanium is a springy alloy cousin to pure titanium (think Silhouette's three-piece mounting). This material is unique to work with as well. In this case it is neither soldered nor welded. If it does have a hinge (unlike Silhouette) the barrels of the hinge is stamped into the temple as it is being formed into a single piece.

"Foil transfer" coloring is more complicated and is usually confined to metal frames. A design is created on a computer, which is then printed on a foil. The plated frame receives a clear lacquer coating. The foil is wrapped over the area where the color pattern is desired. It is then baked in an oven where the ink on the foil essentially melts from the foil into the lacquer coating. Once cooled, the foil is peeled off and the color appears on the frame. CNC and/or laser cutting is often used to reveal various layers of a laminated material. It is possible to "dial in" the depth of the laser cuts desired to control what layer is revealed.

4. Plastic handmade frames (not injection molded) can vary greatly by design. Materials are cut into rectangular pieces about the height and width of the frame front. Modern factories have invested highly in the past decade to automate the milling steps. While traditionally each cut of plastic meant moving the frame from one machine to another, today's computer assisted "CNC" machines feature multiple cutting blades that are directed to make specific cuts and bevels, including the eyewire groove, before spitting it out and grabbing a new piece of material. Multiple layer acetate provides infinite opportunities to cut and reveal various layers and colors. Tumbling for days amidst polishing agents and materials brings out the material's shine, which is then finished by hand polishing. Too much polishing can wear through the frame, destroying it. Meanwhile, temples are shaped and then "shot" with a wire core. Temple ornaments or plaques are attached in a variety of ways, including imbedding them into the plastic.

5. Injection molded eyeglasses frame production are made in yet another way. Materials for optical injected frames are usually propionate, TR-90 (or its derivative), carbon graphite or similar. In each case, the materials come in sacks of pellets. The machine melts the pellets and forces them into a mold of the model's shape. When removed and cooled the part is popped out of the mold and another one is made. Meanwhile that frame part is tumbled smooth. Coloring can be done in the mold. In other words, if you want a black frame you can use black pellets. Other colors are usually spray-painted with paints that can be absorbed by these materials. Patterns can be made on the materials by masking off sections, or even by simply holding a mask up to the plastic when spraying it with color. If you want tortoise, then color the whole frame in a light brown, followed by holding up a mask that has a series of holes and then spraying that mask with a dark brown. Pull the mask away and you have a tortoise-like look. Molds for injection molding can be very expensive so high volume is required for a company to usually invest in molded products.

Some designs call for pad printing or digital printing. Pad printing is simple, printing what is created on a metal plate, the same technique used for most temple and demo lens markings. Digital printing is a relatively new art for eyewear. It is used most often to print any design on a plastic temple. The part is inserted into a special printer that applies the graphic to the plastic.

6. Acetate temples most commonly have their wire core "shot" or ultrasonically embedded into the plastic temple. Sometimes the wire core is also laminated into the temple. There are many core options, which is determined during design. Temple tips may have an embedded logo, which requires precision cutting, laying in of a foil logo and covering with epoxy.

7. Nosepads are chosen to meet a variety of functional and design needs. Size and system is decided upon during the design phase and is made to order during production, including the dimensions and orientation of the pads.

Metal frames also require choosing the type of nosepad arms and pad shape/size.

Acetate frame design requires selecting the size and angle of the pad placement, which depends on the audience. For Asian and African-American fits (those people with a "flatter" bridge) part of the production may have different nosepads, fit lower and with increased depth, flaring wider and faster.

8. Finally the frame is assembled to bring all the component parts together. Frames are adjusted and compared to a CAD drawing to make sure the arc of the front and the bend of the temples are consistent and according to expectations of designs.

9. Cases and packaging are made in parallel at specialty case manufacturers.

10. Nonprescription sunglasses require a decision about bezel design. That determines whether the frame will also be Rxable. A "U-shaped" groove is commonly used for nonprescription sunglasses. A "V-shaped" groove is the common shape for products that will be Rxed. Sun lens material, colors, coatings and if polarized are determined in the design phase. They are sourced from lens manufacturers, and usually edged and glazed at an assembler. Where the sunglass lens work is completed often is the country of origin marking that appears on the frame. As an example, the frame can be made in China and shipped to a lens company in Italy. There, the lens company makes and glazes the lenses into the frame. Expect that frame marking to read "Made in Italy." This is yet another example why you need to know how to evaluate product well beyond the country of origin marking. You also need to provide your patients a good color recommendation for sunglasses.

QUALITY ASSURANCE AND CONTROL

The frame has been manufactured but the quality of the intent must be confirmed. Quality assurance means that quality happens at all stages, not just at the end of production (quality control). Material quality is checked when received from component manufacturers (for example, hinge size and finish, nose-pad color and consistency), then at every stage of production and finally before packaging.

After a visual inspection, the frame is adjusted to the specs for front curve and tilt (pantoscopic tilt angle).

Batch testing is used to ensure that all the design and operational features are delivered as specified.

The functioning of hinges can be tested using a mechanical device that opens and closes the temple hundreds of times to ensure that the hinge will not wear excessively or the screw design won't back itself out of the hole in the first week of wear. The finish is tested using a standard 3M-tape test. Like AR coatings, tape can be used to test adhesion with results predicting years of wearability under normal conditions. In fact, there are a variety of internationally agreed standards that frames meet and in some countries are required. For example, a common test for Europe's CE mark includes a sweat test to determine metal leaching as well as finish durability. Drop ball impact and optical tests for sunglasses and reading glasses are required.

Using the attribute table, review a product's attributes. Consider using the same checklist when showing customers the differences between that $100 and $400 frame. Mix and match the results for each of the categories.

In summary, know your materials. Understand that processes like casting, acid etching, coloring techniques, finishing steps and care, and the like all add to a frame's price. Brand names add to the cost through their required royalty payments and marketing requirements—not necessarily because the frame is any better or more expensive to manufacture. And please don't decide whether to carry a frame based on how it looks on you. You are one of many target markets.

 

Optician Club

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