HOW POLYCARBONATE SUNGLASSES IS USEFULL TO HUMAN BEING
Sunglasses with Style and Purpose. Generally sunglasses has been used by peoples for preventing highly intensive lights, Sun rays, UV rays which can damage eyes permanently, Foreign particle and dust, When peoples are moving outdoor they have faced these all things and most of peoples are sometimes irritate & suffered headache. For protecting their eyes and keep safe, People’s has been used protective wears. Some people used a fashion for stylish life style also.
THE MANUFACTURING PROCESS
- Pigment can be added to lenses in two primary ways, either by adding color to the molten lens material before the lens is formed, or by chemically post-coating the finished lens to achieve the desired colour. In the former method, the colorant additives are incorporated into the lens while the plastic or glass is at high temperatures and still liquefied. Soluble organic dyes or metallic oxide pigments are added to plastic. Metallic oxide or metal particles are incorporated into glass.
- After the appropriate additives have been mixed in, the molten plastic or glass is then cast into the general lens shape, Inexpensive lenses are simple shape that placed into frames. Expensive lenses are prepared in a manner similar to the method by which remedy lenses are made. First the appropriate lens shape is placed in a lensometer, an instrument that is used to find the optical centre of the blank.
- The lens is then put in a curve generator, which grinds out the back of the lens according to the patient’s prescription. An edge grinder then grinds the outer trim to its proper shape and puts a bevel on the edge, allowing the lens to fit properly into the frames.
- Lenses may now be coated with an anti-reflective material. The post-coating method produces lenses that are more evenly coated regardless of the lens configuration. It also allows for the coating to be removed and recoated after the lens is made. Such coating may be applied through a vacuum coating method, used to deposit an antireflective layer on the lens surface to reduce internal reflections. This faint bluish coating is also commonly used on camera lenses and binoculars.
- The finished lenses are now ready to be mounted in eyeglass frames. Frames are constructed to hold the lenses in place using either a tension mount or screw mount design. Tension mounting is typically used in plastic frames. In this type of frame, the dimensions of the lens opening on the front surface of the frame are somewhat smaller than the lens itself. In this way the lenses can be pressed into their respective openings through the front edge of the frame without falling out its rear edge. A groove is formed in the periphery of each of the openings, and these mate with a ridge formed on the periphery of the respective left and right lenses. The plastic frame material permits sufficient stretching or elongation to allow the lenses to snap into these grooves.
- Metal frames use a screw mount design because metal tends to deform easily and cannot hold the lenses as well. The metal structure of the frames has the extruded sections that are bent into desired shapes. The frame structure surrounding the lens openings forms an open loop into which the lens is inserted. After the lens is inserted, the loop is closed by attaching a screw to the two open ends. Finally your sunglass is ready.
RAW MATERIAL USED & PROPERTIES:
Generally two materials have been used to make sunglasses lens i.e Glass or Plastic.
Glass: Optical crown glass still exists for specific purposes, but is now rarely used in this time. The glass lens are superior clarity and best scratch resistance but mainly drawback is weighted and shattering.
Plastic: There are various type of plastic used to make novelty or cheap fashionable sunglasses. And the material is CR-39. CR-39 is still commonly uses not for safety but, for sunglasses and prescription wear.
Apart from CR-39, Acrylic or Polycarbonate, which is shortly known as PC has been highly used to make sunglasses in this time.
Polycarbonate (PC) is a thermoplastic, and is by far the most commonly used material in the safety eyewear industry. It possesses superior impact resistance (about 10 times that of glass and some other plastics), it’s inexpensive, and it also inherently blocks 99.9% of UVA/UVB rays without any extra or special coatings. PC possesses a higher refractive index at 1.59, which makes it useful for prescriptions. It also accepts add-on technologies to result in photochromic or polarized lenses. PC’s biggest drawback is its low scratch resistance. Lenses are usually manufactured with a special scratch resistant hard coat to increase their tolerance Although it is possible to safety eyewear with uncoated lenses. It has little expensive but best suit for safety and outdoor applications.
Frames: are generally made by Nylon, Metal and alloy metal etc.
HOW THE COLOR OF LENS CAN VARY A MEN:
- Gray and green lenses are considered neutral because they maintain true colours.
- Brown lenses cause some colour distortion, but also increase contrast.
- Turquoise lenses are good for medium and high light conditions, because they are good at enhancing contrast, but do not cause significant colour distortion.
- Yellow is “optimum for object definition, but creates a harsh visible light”; amber “allegedly makes distant objects appear more distinct, especially in snow or haze. These lenses are popular with skiers, hunters, boaters and pilots.
- Blue or purple lenses are mainly cosmetic.
- Maiu Jim
- Titan Eye+