If you use eyeglasses, most likely you have wondered what is the step by step process to make them, we. This eyewear, also referred to as spectacles are tools aimed to improve vision but currently, they are also widely considered a fashion item, which is conformed by two pieces of lenses made out of either glass or in some cases hardened plastic. These are then incorporated into a suitable frame that can be composed of several materials (such as plastic, wood, magnesium, beryllium, aluminium, titanium, stainless steel, among others) and has the main function of holding them in front of the user’s eyes.
Most times, this item will have a structure in the middle of the lenses to be placed on the nose, then you will also see a pair of temple pieces that must be hinged over each of your ears. Since glasses can help to correct many eyes’ affections, such as myopia (nearsightedness), hyperopia (farsightedness), presbyopia (age-related farsightedness) or astigmatism, chances are that you will often see a lot of persons wearing them.
How it started
The optical glass made to magnify objects and improve vision capacity was invented in the early 12 century. These lenses were made out of quartz and beryl and it is still considered a game changer in the history of medicine. After this tool was created, the first lenses offered to the public were developed by Alessando di Spina, making it accessible for many people who got the chance to benefit from his invention, and as a consequence of the high amount of persons demanding this item, it was necessary to replace the materials used by regular glass spectacles. At the beginning, their main function was correcting hyperopia, but with the advancement of improved techniques and research, different types of lenses were generated. You have surely heard the name of Benjamin Franklin as an American polymath who was also an inventor, well, among his outstanding inventions we can mention the bifocals, brought to life in 1784.
Currently, a very high proportion of the eyeglasses designed and manufactured all around the glove are produced out of hard plastic, but it was not always so, in fact other materials were preferred before. Up until the first half of the 19 century, the material of choice in the market was hands down the glass, but with the surge of plastic lenses in the year of 1952, things changed and people started to prefer hard plastic over glass as it was more resistant and lightweight.
Different types of glasses
It might be surprising to find out, but glass and plastic spectacles have a very similar production process. In this article we will talk about each step of the manufacture of glasses, including grinding, polishing as well as shaping, which is also very similar to the process followed to create telescopes and cameras, among other vision devices. Now, whether you use corrective lenses as an essential tool in your daily life, or you just use blue light glasses at home to protect your vision from the screens, it might be interesting to know how they are made. In this article we will let you know about each stage of the process.
First of all, the authorized manufacturing laboratories get the so-called plastic blanks, which are small pieces of plastic (it can be composed of many elements, for example polycarbonate that is lightweight, thin, and has a high resistance against impacts). Such blanks initially measure about 1.9cm but are then reduced up to 0.63cm, and this number varies according to the optical effect desired. During the production of glasses there are also some other elements involved, just to mention a few, there is need of adhesive material, metal as well as pigments and different sorts of tints.
Models and types of coatings
Regarding the design of the glasses, they can be sketched in a broad variety of sizes and shapes according to the particular request of the customer, it all boils down to the silhouette of the frames on which the lenses will be mounted. You will often notice a variation in the finish at the edges as well as the thickness of the spectacles, which corresponds to the function expected from this item, in other words, what the customers need to improve in their vision. The lenses are shaped in order to have different effects, which are specific for each person. So, you can often notice some curves on the lenses and this is normal.
After the lenses have been properly shaped, they can receive several types of treatments, including the application of tints. A layer of a certain tint or other type of coating can be applied on the lenses, which is done by immersing them into special cans made out of metal. Some of the tint coatings more common in the optical market are ultraviolet light protective layers, impact-resistant protection in order to enhance the endurance of the product, as well as other newer techniques, including light-sensitive coating. The treatments mentioned so far are done after the shaping process but before the lenses have been mounted into the frames.
Before we start describing each operation and stage in the manufacturing process, keep in mind that the procedure herein explained can only be adequately done at an authorized optical laboratory, since they have the proper conditions and tools to obtain a satisfactory result.
Adapting the lenses
The operator places the lenses and selects the required prescription on the machine to get the optical process done. Then, the lenses are covered with a special tape to avoid any damage such as scratches, and then placed in the blocker machine. Next the lens is placed into a generator that grinds the required shape at the back of each of the lenses. Afterwards, it is necessary to provide a smooth texture by polishing them well.
Now, the technician or designed operator must place the lenses into an edging device, which will provide the lenses with an appropriate form. Then, the gadget inserts a bevel on the corner of the lenses in order for it to conform to the shape of the frames. Lastly, the lenses must be immersed into any additional required treatment, and the the lenses are ready to be inserted into the frames.
Making the Frames
Once the technician knows the design, he will proceed to die-cut the frames by punching the blanks out of acetate sheets, obtaining the fronts part of the eyeglasses. Next, the frames are heated in little warming machines to 68 degrees celsius in order to make the material soft. Now, the frames are placed into a blanking gadget and the die can create a blank. Such blanks can be made fast as long as the plastic is warmed-up. To finish the frames the manufacturers use different types of abrasives, which are often machines. One of them aims to diminish any sharp feel on the edges, in order to avoid any harm to the cheeks area of the users, and the second one softens the area that gets in contact with the nasal septum.
How Temples are done
The pair of arms that rest over your ears are well known as temples or arms, which are punched out in the same way that the lenses’ frame. The common size of the temples measures about 12.7 and up to 15.2cm, and most times they are made out of the same material as the front of the frames. The shape of the temples may vary and this depends entirely on the design, so they can be completely flat or have some curved form that mimics the shape of the head, or something in between.
Then, it is time to add some significant strength to this structure. In order to achieve a more resistant product, the temples are subjected to top temperatures along with a thin strip of steel, which is later incorporated right at the middle of the now flexible temples’ plastic. Perhaps you have noticed that some glasses don’t have this feature nowhere visible, and it is truth that some eyeglasses providers do not add this core wire, especially when this item is a non-prescribed product you can find at some stores, here, you just need to keep in mind that there will be less quality than in those glasses with the extra protection.
Concluding the fronts and the temples
Many manufacturers like to print their logo on the frames and this is one of the last steps. Right after putting together the temples and the front frame it is necessary to give some shape to the structure. For this purpose an automated cutting machine creates specific angles in the superior corners of the front part, which also must be well polished. At the polishing process many of the fronts are finished at the same time in order to provide the desired silky, uniform texture, this operation lasts 24 hours and ensures that any rough edge is properly smoothened. The fronts go through an exhaustive process of tumbling drums.
After that, all the polished parts are visually checked, searching for any damage on the surface and then, they are placed on individual trays, classified by model, color, etc.
The temples have to be ground and softened by many steps. In the same way that the fronts, the temples are polished and packaged in containers according to their model, size, among other features. The manufacturers often put the containers with fronts and temples on stock, waiting for orders to be placed. Once this happens, someone from warehouse support picks the right front and temples, being able to provide the customers with their order.
Every medical equipment or healthcare device must be produced under the most strict measures, in consequence attention to detail is a must, so we can surely state that quality is non-negotiable. In this case, there is a consensus that eyeglasses are critical in improving a person’s vision. Plus, they have to be pleasant to wear for a long time, without causing any damage to the skin (nose, cheeks or ears). It is true that much of the process relies on the machines in order to be done, however, it is essential to have prepared technicians who are able to operate each step in a responsible way. In the same way, every operator should be alert to detect any issue on the product they are making, in fact, this product can become scrap at any stage of the production process.