Piano hinges are a popular type of hinge that allow an attached part, such as a window, to swing. The goals of piano hinges are to support the objects to which they are adhered and reduce the gap between these objects and themselves. Also known as continuous hinges, piano hinges are known for their consistency of strength throughout the entirety of their length and their atypical length. They usually measure at least five inches in length, which is longer than standard hinges, and they often span the length of a whole joint.
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Design of Piano Hinges
Piano hinges are one of the two most common types of recessed hinges, which are hinges that require the wood or other materials to which they are adhered, to be removed so that the hinge can be mortised, or bored, into said material. Piano hinges consist of two independent, flat leaves, the interior of which are curled into alternating knuckles that interlock with one another. The leaves are kept in place by a pin, which runs along the full length of the joint. In addition, the knuckles in the leaves are manufactured in such a way so that each knuckle and knuckle and knuckle and leaf are separated by a gap, called an "end play." The end play enables the hinge to swing at will without the risk of causing friction by rubbing up against itself. In addition, while most piano hinges are fabricated without holes, manufacturers can and do make slotted piano hinges as well. The benefit of having piano hinges without holes is that they make custom hole drilling possible for their specific application or for spot welding. (Spot welding is the process of creating an overlapping hinge joint by welding at a number of small, separate points.) Slotted piano hinges, on the other hand, are the piano hinges to buy for precision alignments ensured by the carefully measured premade holes. Slot hinges are also fairly easy to use; once the holes, or slots, have been created, users need only insert close-spaced fasteners to connect the hinge leaves to the objects they are holding together.
Piano Hinges Process
Piano hinges may be created through roll forming, stamping or extrusion. However, since they are longer than other hinges and because it increases their tensile strength, the most common and best method by which to create piano hinges is the extrusion process. The extrusion process is fairly straightforward. During this process, malleable or plasticized material is sent through a channel to a die, which is a preformed shape, created specifically to give a particular form to the material going through extrusion. When it reaches the dies, the molten material is forced through it, where it fills out and takes its shape. Once it has cooled and hardened, the new product may be removed.
Materials Used in Piano Hinges
While hinges may be extruded using a number of materials, piano hinges are most often extruded from stainless steel, galvanized steel, brass, and, most frequently, aluminum. The decision of what material with which to extrude a hinge depends on the hinge’s intended application. For example, a hinge that will be on display will likely be made of brass or stainless steel, because these metals both have aesthetic appeal.
Brass is an alloy of copper and zinc, known for its bright yellow-gold color, its resistance to corrosion, its low friction, its high workability and its durability. In general, brass is used extensively to create decorative piano hinges.
Aluminum Piano Hinges
Aluminum piano hinges are universally valued for the characteristics of aluminum and aluminum alloys, which include durability, low toxicity, corrosion resistance, ductility and non-ferrous nature. Applications that may require one or more of these characteristics include hinges used with electronics and for use with structural applications like marine operations, furniture, construction, automotives and appliances. Meanwhile, piano hinges made of brass, galvanized steel or stainless steel are most often employed for use with heavy duty applications like ATM machines, barn doors, electronic enclosures, fire truck compartments, storm doors and tool boxes.
Galvanized Steel Piano Hinges
Galvanized steel piano hinges are unique in that they have undergone galvanization, which is the process by which steel or iron is coated in zinc in order to protect it from rusting, corrosion and scratching.
Stainless steel hinges carry the inherent benefits of stainless steel, such as corrosion, rust and stain resistance, as well as hardness and strength. Depending on the grade or type of the stainless steel selected, which varies because stainless steel is an alloy, the prevalence of the specific qualities displayed by a hinge will vary. For example, type 904 stainless steel is resistant to high concentrations of sulfuric acid at room temperature, while type 304 stainless steel cannot tolerate it under any circumstances. To learn more and for guidance with selecting the correct material and piano hinge type, contact a trusted hinge provider.