Living hinge

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Pill box with hinged lids to compartments Pill box with pills.JPG
Pill box with hinged lids to compartments

A living hinge or integral hinge is a thin flexible hinge (flexure bearing) made from the same material as the two rigid pieces it connects.

Contents

Description

A living hinge or integral hinge is a thin flexible hinge (flexure bearing). It is made from the same material as the two rigid pieces it connects. It is typically thinned or cut to allow the rigid pieces to bend along the line of the hinge. The minimal friction and very little wear in such a hinge makes it useful in the design of microelectromechanical systems, and the low cost and ease of manufacturing makes them quite common in clamshell containers and other disposable, recyclable packaging. [1]

Plastic

Plastic living hinges are typically manufactured in an injection molding operation [2] [3] that creates all three parts at one time as a single piece, and if correctly designed and constructed, it can remain functional over the life of the part. Thermoforming can also produce hinged products. Polyethylene and polypropylene are considered to be the best resins for living hinges, due to their excellent fatigue resistance. [4] [5] Acrylonitrile butadiene styrene (ABS) is also common. [6]

Wood

A laser cut plywood box with two living hinges Living hinge (wood).jpg
A laser cut plywood box with two living hinges

A variant on the kerf bend can be used to create living hinges in laser cut wood. The technique is popular for making light-duty hinges with large radii. [7] It is also possible to create a living wood joint by hand, but the result is less accurate. [8]

See also

Related Research Articles

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A thermoplastic, or thermosoftening plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.

<span class="mw-page-title-main">Polypropylene</span> Thermoplastic polymer

Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene.

<span class="mw-page-title-main">Acrylonitrile butadiene styrene</span> Thermoset polymer

Acrylonitrile butadiene styrene (ABS) (chemical formula (C8H8)x·​(C4H6)y·​(C3H3N)z ) is a common thermoplastic polymer. Its glass transition temperature is approximately 105 °C (221 °F). ABS is amorphous and therefore has no true melting point.

<span class="mw-page-title-main">Flexible electronics</span> Mounting of electronic devices on flexible plastic substrates

Flexible electronics, also known as flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additionally, flex circuits can be screen printed silver circuits on polyester. Flexible electronic assemblies may be manufactured using identical components used for rigid printed circuit boards, allowing the board to conform to a desired shape, or to flex during its use.

<span class="mw-page-title-main">Hinge</span> Mechanical bearing connecting two objects

A hinge is a mechanical bearing that connects two solid objects, typically allowing only a limited angle of rotation between them. Two objects connected by an ideal hinge rotate relative to each other about a fixed axis of rotation, with all other translations or rotations prevented; thus a hinge has one degree of freedom. Hinges may be made of flexible material or moving components. In biology, many joints function as hinges, such as the elbow joint.

<span class="mw-page-title-main">Injection moulding</span> Manufacturing process for producing parts by injecting molten material into a mould, or mold

Injection moulding is a manufacturing process for producing parts by injecting molten material into a mould, or mold. Injection moulding can be performed with a host of materials mainly including metals, glasses, elastomers, confections, and most commonly thermoplastic and thermosetting polymers. Material for the part is fed into a heated barrel, mixed, and injected into a mould cavity, where it cools and hardens to the configuration of the cavity. After a product is designed, usually by an industrial designer or an engineer, moulds are made by a mould-maker from metal, usually either steel or aluminium, and precision-machined to form the features of the desired part. Injection moulding is widely used for manufacturing a variety of parts, from the smallest components to entire body panels of cars. Advances in 3D printing technology, using photopolymers that do not melt during the injection moulding of some lower-temperature thermoplastics, can be used for some simple injection moulds.

<span class="mw-page-title-main">Molding (process)</span> Shaping a liquid or plastic material by making it conform to a more rigid mold

Molding or moulding is the process of manufacturing by shaping liquid or pliable raw material using a rigid frame called a mold or matrix. This itself may have been made using a pattern or model of the final object.

<span class="mw-page-title-main">Flexure bearing</span> Type of mechanical bearing

A flexure bearing is a category of flexure which is engineered to be compliant in one or more angular degrees of freedom. Flexure bearings are often part of compliant mechanisms. Flexure bearings serve much of the same function as conventional bearings or hinges in applications which require angular compliance. However, flexures require no lubrication and exhibit very low or no friction.

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<span class="mw-page-title-main">Closure (container)</span> Devices and techniques used to close or seal a bottle, jug, jar, tube, can, etc.

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<span class="mw-page-title-main">Flexure</span>

A flexure is a flexible element engineered to be compliant in specific degrees of freedom. Flexures are a design feature used by design engineers for providing adjustment or compliance in a design.

<span class="mw-page-title-main">Rotational molding</span> Making hollow plastic objects in a heated mold

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In-mould labelling is the use of paper or plastic labels during the manufacturing of containers by blow molding, injection molding, or thermoforming processes. The label serves as the integral part of the final product, which is then delivered as pre-decorated item. Combining the decoration process with the moulding process cuts the total cost, but can increase the manufacturing time. The technology was first developed by Owens-Illinois in cooperation with Procter & Gamble to supply pre-labelled bottles that could be filled on the product filling line. This was first applied to Head & Shoulders shampoo bottles.

Thermoplastic vulcanizates (TPV) are dynamically vulcanized alloys consisting mostly of fully cured EPDM rubber particles encapsulated in a polypropylene (PP) matrix. They are part of the thermoplastic elastomer (TPE) family of polymers but are closest in elastomeric properties to EPDM thermoset rubber, combining the characteristics of vulcanized rubber with the processing properties of thermoplastics. There are almost 100 grades in the S portfolio that are used globally in the automotive, household appliance, electrical, construction, and healthcare markets. The name Santoprene was trademarked in 1977 by Monsanto, and the trademark is now owned by Celanese. Similar material is available from Elastron and others.

<span class="mw-page-title-main">Compliant mechanism</span> Mechanism which transmits force through elastic body deformation

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<span class="mw-page-title-main">Twinwall plastic</span>

Twin-wall plastic, specifically twin-wall polycarbonate, is an extruded multi-wall polymer product created for applications where its strength, thermally insulative properties, and moderate cost are ideal. Polycarbonate, which is most commonly formed through the reaction of Bisphenol A and Carbonyl Chloride, is an extremely versatile material. It is significantly lighter than glass, while managing to be stronger, more flexible, and more impact resistant. Twin-wall polycarbonate is used most commonly for green houses, where it can support itself in a structurally sound configuration, limit the amount of UV light due to its nominal translucence, and can withstand the rigors of daily abuse in an outdoor environment. The stagnant air in the cellular space between sheets provides insulation, and additional cell layers can be extruded to enhance insulative properties at the cost of light transmission.

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Flexure may refer to:

References

  1. "Engineering Fundamentals: Living Hinge". Archived from the original on 2008-02-28. Retrieved 2008-02-26.
  2. Sievers, R M (2005), SIMULATING THE POLYPROPYLENE FILLING OF A DISPENSING CLOSURE MOLD WITH INJECTION MOLDING SOFTWARE (PDF), 2005 IL/IN Sectional Conference: American Society for Engineering Education, archived (PDF) from the original on 19 May 2021, retrieved 18 May 2021{{citation}}: CS1 maint: location (link)
  3. Kim, HS (2003). "Gate location design in injection molding of an automobile junction box with integral hinges" (PDF). Journal of Materials Processing Technology. 140 (1–3): 110–115. doi:10.1016/S0924-0136(03)00700-3. Archived (PDF) from the original on 19 May 2021. Retrieved 18 May 2021.
  4. "Proto Labs 2014-12 Design Tips". Archived from the original on 2017-12-01. Retrieved 2017-11-21.
  5. Dominic Muren (2005-08-15). "Hinges, both living and dead". Archived from the original on 2007-10-13. Retrieved 2008-02-26.
  6. Gribbins, C (2014), EXPERIMENTAL ANALYSIS ON AN ADDITIVELY MANUFACTURED ABS LIVING HING (PDF), University of Texas,25th Annual International Solid Freeform Fabrication Symposium, pp. 1412–1424, archived (PDF) from the original on 18 May 2021, retrieved 17 May 2021
  7. Sean Michael Ragan (2011-10-25). "Plywood Living Hinge Design for Laser Cutters".
  8. "Cutting A Living Hinge". YouTube . Archived from the original on 2021-12-05.