Frame Materials (1) PDF

OPHD 2604 Frames Different Types & Parts Chapter 1 14 February 2024 Basic parts: A frame generally consists of: Front – which contains the lenses Temples – which attach to the front and hook over the ears to help hold the spectacle...

OPHD 2604 Frames Different Types & Parts Chapter 1 14 February 2024 Basic parts: A frame generally consists of: Front – which contains the lenses Temples – which attach to the front and hook over the ears to help hold the spectacles in place  Basic parts: Hinge /Joints: Holds the temple to the front Consists of inter-fitting barrels Made of metal Two parts: One attached to frame front and one to the temple When temple is made of memory material = no hinge Spring hinges use spring tension to press closer to the head for snug fit ― More expensive  Some general terms and definitions: Front – The part of the frame or mount comprising the bridge, rims and joints Bridge – Part of the front which form the main connection between the lenses or rims Rim (eyewire) – Part of the frame/ mount which partly or completely surrounds the lens Pad (nosepad) – Extension / attachment to the bridge or the rim to bear on the nose Joint (hinge) – The hinge linking the temple and the front Temple – Extension or attachment to the front passing towards or over the ear Endpiece – Extension at each end of the front to which the joint or temple is attached Frame materials: 1. Cellulose Acetate PLASTIC 2. Propionate 3. Optyl 4. Nylon 5. Polyamide 6. Grilamid Generally made from one of these types of materials 7. Carbon Fiber Originally was known as ‘shell’ because frames were traditionally made form 8. Polycarbonate tortoise shells 9. Kevlar More well known as ‘zyl’ ― Cellulose nitrate (zylonite) is 10. Rubber commonly used to make frames 1. Cellulose Acetate: Extracted from cotton or wood pulp and then processed Treated with a mixture of anhydride and acetic acid using sulphuric acid as a catalyst Plasticizers and aging stabilisers are added as well Does become brittle with age Can cause allergic reactions – rare Coated – reduces allergies and UV damage Can be cut from sheets or used with injection molding Thermo-plastic – will bend when heated, but does not return to it’s original shape when reheated 2. Propionate: ‘Cellulose aceto-propionate’ Many of the properties of cellulose acetate Works better with injection molding Less colour stability than cellulose acetate ― Has to be coated with UV stabilisers to prevent loss of colour ¾ of the weight of cellulose acetate 3. Optyl Epoxy resin Liquid resin is mixed with hardener Thermo-elastic – will bend when heated, and will return to it’s original shape when reheated 30% lighter than cellulose acetate 4. Nylon High flexibility Nylon will lose it’s flexbilitiy unless it is periodically soaked in water overnight to retain flexibility Will become brittle over time if not soaked Over the counter sunglasses and sports eyewear Not used extensively 5. Polyamide Nylon-based Quite strong Thinner 72% of the weight of cellulose acetate ― Weight advantage Translucent or opaque Hypo-allergenic 6. Grilamide Nylon based material Used for sports and performance type of eyewear Large variety of colour 7. Carbon Fiber Thin, strong frames Made from strands of carbon fibers combined with nylon Since carbon fiber is black – frame colours are mostly opaque frames and limited in colour Not adjustable – mainly used for frame fronts ― Temples are generally made from a different material 60% lighter than cellulose acetate Cold weather can affect the material and cause breakages 8. Polycarbonate Usually a lens material Can be molded into frames Mostly used for safety or sport frames When made for non-prescription purposes it can be molded as a single unit Highly impact resistant Resistant to adjustment – not a good choice for conventional eyeglasses 9. Kevlar Mixed with nylon Strong, light weight material Remains stable over large temperature range Difficult to adjust Becomes pliable with heat, but will not stretch or shrink 10. Rubber Sports eyewear and sunglasses Can be made from a combination of nylon and rubber Flexible and will return to their original shape – therefore not adjustable Frame materials: METAL 1. 2. 3. Nickel silver Monel metal Aluminium Those frames made of all metal parts, 4. Stainless Steel except for the nose pads and the posterior temple section, which are plastic covered. 5. Titanium The eyewire runs completely around the lens 1. Nickel Silver Composition: More than 50% copper, 25% nickel and 25% zinc ― Copper: pliability ― Zinc: strength No silver Nickel – whitish appearance If the nickel content exceeds 12%, the copper colour no longer shows through 2. Monel Metal Composition: Nickel (63-70%), copper, iron(2.5%) and traces of silicon, carbon and sulfur Often used Whitish Pliable Resists corrosion Accepts a high polishes 3. Aluminium Strong Lightweight Can be finished in a wide variety of colours Does not corrode Does not solder or weld well, so it must be assembled using screws and rivets 4. Stainless Steel Composition: Iron and chrome 19th century – used regular steel Highly resistant to corrosion Strong Element of flexibility if thin – suitable for temples 5. Titanium Extremely lightweight Will not rust Expensive Hard to solder or weld Hypo-allergenic Frame materials: HYPO-ALLERGENIC To reduce the possibility of a reaction for people who have a history of skin reactions to wearing frames Materials most suited: What to do if a person already have reaction to the frame they are wearing: 1. Optyl material 1. Have a clear coat finish applied to the frame 2. Polyamide 2. Use ultrathin, clear heat-shrink tubing over the temples 3. Titanium If a person has an allergic reaction to nosepads, the following replacement pads can be used: 4. Stainless steel 1. Gold-plated metal nosepads 2. Titanium nosepads 3. Crystal nosepads Frame Construction: 1. Plastic 2. Metal 3. Nylon Cord 4. Combination 5. Half-eye 6. Rimless Mountings FRAMES WITHOUT AN EYEWIRE GOING 7. Semi-rimless Mountings COMPLETELY AROUND THE LENS ARE CALLED MOUNTINGS 8. Numount Mountings Lenses are “inserted” into frames, but “mounted” into mountings 3. Nylon Cord Frames Also known as nylon supra or string mounted frame These mount holds the lenses in place by means of a nylon cord that fits around the edge of the lens This gives the glasses the appearance of being rimless The top of the lens is fitted into the upper rim of the frame The rest of the lens has a small groove cut into an otherwise flat edge 4. Combination Are commonly frames having a metal chassis and plastic top rims and temples The chassis includes the eye wire and center or bridge section Any frame with a combination of metal and plastic could be included in this category, as in the case of frame with plastic eye wire and metal bridge and temples 5. Half-Eye Frames made especially for those who need a reading correction but no correction for distance Sit lower on the nose than normal, and are only half as high as normal glasses This allow the wearer to look over the top of the glasses to see in distance 6. Rimless Mountings Rimless holds the lenses in place by some method other than eyewires or nylon cords Normally by screws, cement, clamps and solder plugs Most rimless mountings are called 3-piece mountings 6. Rimless Mountings Classic Rimless Fronts: Rimless centre piece consists of the bridge, pad arms and pads Rimless point of attachment contains a “strap” ― Contacts front and back surfaces and edge of the lens ― Holds lens in place Traditional strap consists of the shoe and the ear Shoe/shoulder/collar: Contacts the edge of the lens prevents rocking back and forth Spring: Between shoe and lens, keeps lens tight Ear/tongue: Extends from the shoe, contacting the surface of the lens Arm/bar/brow bar: Part of semi-rimless mounting that extends posteriorly along top edge of lens Endpieces are same as for metal Have straps to hold lenses and hinges for temples. 7. Semi-Rimless Mountings Similar to rimless except: ― it has a metal reinforcing arm that follows the upper posterior surface of the lens ― metal arm joins the centerpiece of the frame to the end piece The centerpiece of a mounting consists of a bridge, guard arms, and pads 8. Numount Mountings Hold the lenses in place only at their nasal edge The lenses are attached at the bridge area and the temples are attached to a metal arm that extends along the posterior surface temporally Bridge Construction: The bridge area of a frame can be constructed of either plastic or metal but is usually of a material consistent with the frame Two main types: 1. Plastic: - Saddle bridge - Modified saddle bridge - Keyhole 2. Metal: - Pad bridge - Comfort bridge - Metal saddle bridge  Plastic frames are constructed so that the bridge area sits PLASTIC BRIDGES: directly on the bridge of the nose Important!! When choosing a plastic frame, ensure that the frame fits the nose well since adjustments to this part of the frame are difficult 1. Saddle bridge: Shaped like a saddle in a smooth curve Follows the bridge of the nose smoothly Spreads weight of the frame evenly over the sides and crest of nose PLASTIC BRIDGES: 2. Modified Saddle Bridge: Also known as a semi-saddle Has a bridge that looks much the same as the saddle bridge from the front, but nose pads are attached to the back of the bridge and carry some of the weight of the frame PLASTIC BRIDGES: 3. Keyhole: Shaped like an old-fashioned keyhole at the top, flares out slightly, and rests on the sides of the nose but not on the crest Most keyhole bridges utilize nose pads to help support the frame. METAL BRIDGES: 1. Pad Bridge: Is the most common bridge used for metal bridges Nose pads are attached to the frame by metal guard arms The pads alone support the weight of the glasses. METAL BRIDGES: 2. Comfort Bridge: When a metal frame is equipped with a clear plastic saddle-type bridge METAL BRIDGES: 3. Metal Saddle Bridge: Designed to directly rest on the crest of the nose Metal and rimless frames can be constructed with a metal saddle bridge which is sometimes referred to as a “W bridge” Bridge Crest: The crest of the bridge does not include the pads, but is the center most area 3 main types: 1. The low crest bridge has little or no actual crest area 2. The high crest bridge begins at the level of the pad attachment and arches up considerably 3. The bar bridge has no actual crest area, only a bar running from the top of one lens to the top of the other Bridge Crest: The bar bridge has no actual crest area, only a bar running from the top of one lens to the top of the other  End-Piece Construction: PLASTIC 3 main types: 1. Mitre Frame front contact area and temple butt meet at a 45° angle 2. Butt – most common The front is straight and the temple butt is flat and they meet at a 90° angle 3. Turn back The frame front bends around and meets the temple end to end  End-Piece Construction: METAL The traditional metal endpiece has a contruction similar to the turn-back design of the plastic frame Some metal endpieces are not really endpieces at all ― Instead the endpiece and temple are one continuous piece of material Temple Construction: 5 main types: 1. Skull 2. Library 3. Convertible 4. Riding Bow 5. Comfort Cable 1. Skull Temple: Bend down behind the ear and follow the contour of the skull, resting evenly against it The bent-down portion is narrower as the top of the ear and widens toward the end 2. Library: Usually begin with an average width at the butt, increases posteriorly They are practically straight Hold the glasses primarily by pressure against the side of the head 3. Convertible: Originally designed so they could be bent down to take on the form of the skull temples, and ‘converted’ from straight-back to skull design Versatile temple Can be made to fit people with a variety of temple length requirements Very easy to re-bent the temple to fit the patient 4. Riding Bow: Curves around the ear, following the crotch of the ear where the ear and head meet and extend to the level of the earlobe Children / safety 5. Comfort Cable: Same shape as riding bow Metal construction unlike the riding bow The portion behind the ear is constructed from a flexible coiled cable ᴥ Different Types of Hinges: 1. Standard/Barrel Hinges The standard hinges are the most popular and widely used hinge style Also known as ‘barrel hinges’ Made of a series of metal rings (or barrels) that fit together like a zipper with a small screw that holds them all in place Each barrel can be adjusted slightly with a small pair of pliers, allowing the glasses to be adjusted comfortably to the wearer’s face People tend to like standard hinges because they’re affordable, durable, and easy to repair ᴥ Different Types of Hinges: 2. Spring/Flex Hinges Great choice for individuals with an active lifestyle Also known as ‘flex hinges’ Come with a spring that allows the glasses arms to bend past 90 degrees Makes the glasses more flexible and more easily fitted to the individual’s head Allow the glasses to twist and bend without snapping or pinching the wearer ᴥ Different Types of Hinges: 2. Spring/Flex Hinges Missing screw - difficult to align the barrels to insert a new screw once the hinge has pulled back into the casing Easy way to solve this? SOLUTION = Special spring hinge screws! ᴥ Different Types of Hinges: 3. Hingeless As the name suggests, no hinges at all Have curved temples moulded to fit the shape of the wearer’s head while still being comfortable to wear Arms are usually made from strong yet pliable metal and are very durable because they don’t have any tiny intricate workings Hingeless glasses are recommended for people who live a very active lifestyle or work manual labour Children frames Tutorial: 1 Tutorial: 2 Tutorial: 3 Tutorial: 4 Tutorial: 5 Tutorial: 6 Tutorial: 7 Tutorial: 8 Tutorial: 9 Tutorial: 10 Tutorial: 11 Tutorial: 12 Tutorial: 13 Tutorial: 14 Tutorial: 15 Tutorial: 16 END!