Post 353 ⇒ by Gautam Shah →
A Hinge is component that attaches an edge of a door to the frame, while allowing the other edge to swing from it. A hinge can also be just an arrangement -a type of relationship between two objects that allows a limited range of mutual rotation, and prevents their easy separation. There are two settings for the Hinge: 1. A hinge connects a stationary object, the frame and a movable object -the shutter; and 2. Two objects are mutually connected and can rotate relative to each other about a fixed axis of rotation (the geometrical axis of the hinge).
Hinges consist of a pair of plates, each with a set of open cylindrical rings or the knuckles formed out of it or attached to them. The knuckles of the two plates are offset from each other and mesh together. A hinge pin is then placed through the two sets of knuckles to form a single unit.
A Door usually requires minimum two hinges. When the door is open, the top one is under pulling out force or tensile stress, whereas the bottom one is being pushed in, or is compressed. Additional mid-hinges, whatever their number, in open or closed positions of the door, are all load bearing hinges, to carry the load of a shutter downward.
Average sized or domestic panelled doors have three stiles and a hinge is placed close to these junctions. For easy and full 180° of opening of the shutter the pin section or the cylinder is positioned out of the face of door and frame. Door frames and shutters with heavy mouldings or casings interfere in the resting of the opened shutter, for such conditions hinges of larger width are used. Such offset hinges allow greater outward projection of the pin or cylinder section. Butt or mortise Hinges are fixed flush or inside the face of door and frame that is inset -mortised. These type of fixing limits the range of opening, but conceal the hinge..
STRAPS: The first door shutter holding devices were straps of leather, ropes, vines, and threads, fabrics. Straps are still used in some conditions where metal friction is likely to cause sparks of erosion (petroleum solvent plants and cordite plants), but are made from new technology materials such as woven Fiber glass, Teflon, Cavalar, and Carbon fiber composites.
PIVOTS: pivots are hinge devices, fixed at top and bottom corners of a shutter to form an axis of movement. Pivots are fixed on outside the edge of a door open to the inside. Pivots fixed on inside an edge of a door allow the door to open outside. Doors with middle edge pivots can swing in both directions, provided the door frame does not obstruct. Pivoted doors opening in or out are sealed at the edge by the portal frame or architectural surrounds. Two-way swinging doors with mid pivots, cannot seal the gap completely. Doors with heavier materials such as stones, cast bronze and wood require pivots. Pivots were initially formed out of the shutter material itself, but later these were lined with metal sheaths. With better technologies, the pivots were formed from cast bronze or iron steel and then attached to the shutters. By the time iron hinges began to be used, the door shutters had become lighter. For pivoted doors no frames are necessary. Pivots are also called pivot hinges or double-acting floor hinges because opening movement is allowed in both directions as similar to hydraulic floor pivots used for glass doors in modern buildings.
EARLY HINGES: Early hinges were really wall-hung pivots, where the pin was hung off a side wall, and the girth or ring was fixed to the shutter. The ring had a long band which was fixed with nails to the stiles or rails. The early long armed hinges have become an expression of a medieval door. Flanged Hinges formed of steel, bronze and brass alloys are being used since middle ages.
MODERN HINGES: These are available of brass, bronze, mild steel, stainless steel, ABS and polypropylene plastics, carbon composites, etc. Most of the commercial hinges are made of several components, such as flanges, flange edge liners, pins, pin cylinder liners, coil springs, hydraulic cylinders, etc.; and these are again composed of many different materials.
BUTT OR MORTISE HINGES: Butt hinges are double flanged hinges with three, five or multiple knuckles. Butt hinges are available for several door and cabinet applications such for mortised fixing, offset, full wrap non-mortise, and half wrap non-mortise fixing. A mortise is a niche to accommodate the flange of a butt hinge. Butt a hinge can also be fixed without a mortice chase. These are also known as shangles in old Tudorian English (large flanged hinges on doors).
BARREL HINGE: These Lift-off butt hinges have two components. The bottom section has a cylinder like projection over which a top hollow ring or cylinder is set. The shutter can be lifted off its position for servicing, cleaning etc. These are used in some kitchen cabinets. A loose pin hinge or ball-tipped hinge, serves the same purpose as the liftoff butt hinges. A removable pin holds two halves of the hinge knuckles together.
FLUSH HINGE: These hinges are mounted on the surface, rather than on the side edge of the shutter, and do not require a mortise or recess to be cut. The hinge fixing screws come-off when the shutters are opened to a wide angle (beyond 180°). These are not as strong as butt hinges, but can be used for lightweight doors and cabinets.
KNUCKLE HINGES: These are flush butt hinges, fixed over the face of the door and its frame, and so not mortised. The pin cylinder or the knuckle is designed to be an expression.
PARLIAMENT OR BUTTERFLY HINGES: These known as Dovetail hinges, were used for cabinets from the 17th C. onwards. The size and form of these hinges vary depending on the use (offset required). Very small ones are used for jewellery boxes or caskets and large ones used in public buildings like Parliaments and halls. For deep-set door frames Parliament hinges are used to park the shutter along the corridor.
STRAP HINGE: A strap hinge has a small height but with a wider flange that accommodates two or three screws in a row on each flange. A back flap hinge is exactly the opposite version of the strap hinge. It has a squarish flange (height and width are nearly equal) Both are used in furniture items.
LIVING HINGE: A living hinge is a thin strip of moulded plastic, with a marked line along which it part can bend. If properly designed and made, its closing and opening capacity lasts for more than a million cycles without failure. It is a thin flexible hinge with flexure bearing. It is formed during injection moulding process of plastics or composites. Such hinges are used on lunch boxes and shampoo or hair oil bottles, and are formed of deformable plastics such as polyethylene, PVC, polypropylene, etc.
PIANO OR CONTINUOUS HINGES: These hinges are long enough to cover the entire edge length of the shutter, so prevent warping of a thin shutter like a Piano top. These are used in cupboards, pianos, bureau, and desk top shutters.
INVISIBLE HINGES: These are used for joining two shutters. These are fully mortised as centered on the door shutter’s face. Door shutters seem like units of wall panelling as hinges are completely invisible.
CONCEALED HINGES: These are not seen outside a closed shutter, and mainly used for furniture doors. These are often spring loaded with self-closing features, and with or without a dampening system (slowing down the closing speed during the last few degrees). They are made of two parts: One part is the hinge cup and the arm; the other part is the mounting plate. These normally come in two sizes, 25 mm and 36 mm. The hinge is adjustable, so once fitted can be adjusted to match the door alignment and planner straightness. These hinges are designed for use with chipboard and MDF.
DOUBLE ACTION HINGE: These have three flanges. The middle flange has hinged flanges on either side. The edge flanges are mortised into the side of the shutter, but the middle flange remains off the sides. The assembly leaves a space between the door shutter and its frame or other shutter. The hinge allows the shutter to open in both directions. Double action spring hinges have spring-loaded mechanisms so that closing action is automatic. Such hinges are used in saloon, bars, banks and government cabin doors.
UNEQUAL FLANGE HINGES: These have unequal flanges in terms of width. A thin shutter has thin flange compared to wider flange for the frame side. Unequal hinges also have a greater length of flange to compensate the reduced width of the flange.
FRICTION STAYS: Friction stays are fitted at top and bottom edges of the surface, and used on French door like systems. Such hinges allow a door to stay-put in its position in spite of heavy winds, and so proves an ideal fixture on windy faces such as sea shores, mountain valleys etc. The hinge requires framing at least at the top and bottom, making it better suited for windows. It has a sliding channel within which a component fixed to the bottom of the shutter, for converting the rotational movement of opening into a linear thrust, through a collapsible triangular arrangement.
ASKEW OR VERTICALLY MISALIGNED PIVOTS OR HINGES: Fort doors had askew or vertically misaligned pivots or hinges, so in case of an emergency the door would be released from its catch to close fast, and automatically, but this also requires greater man power to open it and a stronger stay to keep it open. Similar systems are employed in modern hospitals, class rooms, garden, and toilets doors, where closed doors are preferred. Hydraulic or spring door-closer do the same function. In refrigerators a magnetic gasket pulls and keeps the door shut. Refrigerators often have doors locking hinges on both sides, allowing a door to be opened on left or right side. Salon and government offices have a flap or mid door shutters, with a double flange hinge that can open it both-ways, and also has a spring-coil to bring the shutter to the closed position.