This article takes an in depth look at Concealed Hinges.
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A concealed hinge, also known as a hidden or European hinge, is a hinge that lays flush on the interior of a cabinet door and the surface of the cabinet to provide a smooth outer appearance. There are several varieties of concealed hinges with different leaf designs, pin sizes, and lengths. Concealed hinges for industrial applications are capable of supporting doors weighing 50 lbs up to 90 lbs., which makes it possible to install short wide panels.
Modern concealed hinges are designed for use with various door types and offer features such as soft-close mechanisms, adjustable arms, and easy removal. These hinges are manufactured from materials like steel, zinc, stainless steel, and aluminum. Heavy-duty variants, which must support substantial weight and stress in industrial settings, are typically made from aluminum, stainless steel, or cold-rolled steel, and are often finished with zinc plating, passivation, or electropolishing.
Concealed hinges adhere to the classic hinge design, featuring components such as a pin, leaves, and knuckle. However, each type of concealed hinge may have different attachment methods and might necessitate cabinet modifications during installation. One notable variation is the cup hinge, which deviates from the traditional pin, leaf, and knuckle configuration. Installing a cup hinge requires adjustments to the interior wall of the cabinet.
Another form of concealed hinge is an enclosure hinge that has the pin, leaf, and knuckle design with a quick lease pin, which makes it easy to remove the door to an enclosure. Enclosure hinges are a form of industrial hinge for electrical enclosures. The quick release pin makes it possible for workers to access an electrical cabinet without the inconvenience of a door blocking their way.
The hinge cup is the component that attaches to the cabinet door. Common bore diameters for the hinge cup are 26, 35, and 40 mm. The depth of the bore can vary depending on the design of the hinge arm. The hinge cup features two flanges on its back for securing it with screws to the door.
The hinge arm, often considered the central component of the hinge, incorporates most of the design features. It connects the hinge cup attached to the back of the door with the mounting plate fixed to the cabinet frame. The hinge arm comes in various designs to accommodate different types of cabinet doors and to meet specific travel or end play requirements.
The main components of a concealed hinge include the hinge cup and hinge arm, which are usually assembled together. Typically, a complete concealed hinge set consists of two distinct parts: the main hinge and the mounting plate. For more compact applications, single-piece hinge sets are also available.
The mounting plate is attached to the edge, side, or frame of the furniture and typically features two or four mounting holes, depending on the door's weight or load requirements. It includes notches, clips, or holes designed to secure the hinge arm.
Industrial enclosure concealed hinges are crucial for maintaining the security and safety of enclosures and cabinets, significantly contributing to operational efficiency. These hinges are available in a range of designs, from basic models with screw holes and curved brackets to more advanced versions featuring specialized brackets, unique screws, quick-release removable pins, and custom-designed leaves.
The curved pivot facilitates smooth swinging of the cabinet door and may be equipped with holes for attachment to wooden cabinets or designed without holes for welding onto metal cabinets.
Concealed hinge brackets are comparable to those found in traditional hinges and may come with or without pre-drilled holes.
Industrial enclosure hinges feature a removable pin that allows easy detachment, enabling the brackets to stay in place while providing access to the cabinet's contents.
Electrical box concealed hinges are specifically crafted for use with cabinets and enclosures housing electrical circuits, connections, and breakers. They are engineered for rapid removal, facilitating repairs or replacements of electrical components. These hinges are robustly constructed from materials that can endure environmental exposure and corrosive elements.
The key components of an electrical box concealed hinge include:
The heavy-duty steel quick release pin features an easily accessible element on top for straightforward removal, allowing the door of a box or cabinet to be detached.
The box leaf is equipped with holes for bolts that secure the hinge body to the utility bracket.
Hex bolts are used to firmly secure the hinge body to the utility bracket.
The lid leaf is secured by the quick release pin, allowing it to rotate around this pin when the box or cabinet is opened. It connects to the hinge body in the conventional manner, with a knuckle fitting into the knuckle of the hinge body.
Overlay and reveal are key terms used to define the design of cabinet doors and concealed hinge specifications. These dimensions impact both the positioning of the door and the overall aesthetics of the cabinet.
Overlay refers to the extent to which the cabinet door covers the edge or frame of the cabinet. Conversely, reveal denotes the portion of the edge or frame that remains visible when the door is closed.
Variations in overlay and reveal give rise to the three primary classifications of concealed hinges.
This type of concealed hinge is employed in cabinets where the door aligns with the front edge of the cabinet box or frame. When the door is closed, its perimeter sits flush against the edge of the cabinet panels.
Full overlay does not always imply that the door entirely covers the cabinet box. Certain designs allow for a degree of reveal. Most datasheets for commercially available concealed hinges provide mounting plate dimensions, enabling the precise adjustment of overlay and reveal as needed.
In a half overlay concealed hinge setup, two cabinet doors cover the cabinet's frame and meet at the center of the frame. This central meeting point includes a partitioning wall or center post where the concealed hinge is affixed. The hinge arrangement ensures that both doors can open simultaneously without colliding.
Curved pivot concealed hinges are particularly suitable for half overlay configurations due to their compact size and ease of attachment to both wood and metal cabinets.
Half overlay installations are achieved with the use of a cranked hinge arm and a raised mounting plate, which collectively minimize the overlay of a single door.
Inset concealed hinges are designed for doors that fit within the cabinet panel or frame, resulting in no overlay. This configuration ensures that the outer face of the door is flush with the outer surface of the cabinet frame or edge of the cabinet box.
Inset concealed hinges feature a highly cranked hinge arm and a raised mounting plate to completely eliminate any overlay.
Pivot concealed hinges are designed for cabinets with inset doors where the hinges must be discreet. These hinges consist of two flat leaves, an L bracket attached to one of the leaves and the knuckle, and either a permanent or removable pin, with the removable pin version typically used in industrial settings. They ensure smooth operation and are suited for holding lightweight doors in industrial applications.
In addition to the desired overlay, cabinets may feature various frame constructions. It is essential to use the appropriate hinge type to ensure proper attachment and functionality.
This hinge is designed for cabinets with plain or exposed side panels, utilizing mounting screws fixed perpendicular to the mounting plate. Frameless-type concealed hinges can be configured as full overlay, half overlay, or inset hinges.
A face frame cabinet features a small fascia installed on the side panels. The mounting plate design of face frame-type concealed hinges varies between full overlay and inset types. For full overlay hinges, the mounting plate has screws oriented perpendicularly to the plate. In contrast, the screws for inset hinges are aligned at an angle and fixed to the backside of the frame.
Special concealed hinge designs are available for less common cabinet types, typically found at the inside and outside corners of furniture. Examples of concealed hinges suited for these areas include:
This hinge is designed for use with double doors in L-shaped corner cabinets. Standard concealed hinges, whether overlay or inset, attach the door assembly to the cabinet frame, whereas bi-fold concealed hinges are used to join the two doors together. This setup creates a folding door mechanism, with one side hinged directly onto the cabinet.
These hinges are designed for use in inside-corner cabinets where the side panel is aligned and flush with the door. Many blind corner hinge arms are designed to allow the cabinet door to open up to a full 90°.
Commonly referred to as angled concealed hinges, corner concealed hinges are designed for doors mounted at the outer corners of furniture. While many furniture pieces have 90° angles at the corners, options are also available for 30° and 45° angles. A corner concealed hinge is available to match the specific angle of the furniture.
Concealed or invisible hinges are commonly chosen for industrial enclosures, doors, and cabinets for several key reasons. Primarily, they enhance security, safety, and protection against tampering with sensitive or valuable equipment. In these settings, concealed industrial hinges remain hidden and out of reach, ensuring that the equipment remains secure.
Concealed industrial hinges are commonly found on interior doors and various types of security doors as well as commercial refrigerator doors and tightly sealed enclosures and cabinets. Unlike typical hinges that are completely visible, concealed hinges for industrial use are hidden, flush, and invisible offering exceptional security and protection.
Hold door closed concealed hinges use spring tension to automatically close the door once it is opened, eliminating the need for a latch. They are ideal for high-traffic areas where doors must stay closed to avoid obstructing workers' paths.
Surface-mounted concealed hinges are essential when durability, compactness, flush fitting, and smooth functionality are required. These single-action hinges can open up to 180 degrees and are suitable for attachment to both wood and metal surfaces on industrial cabinets.
For electrical enclosures, cabinets, and boxes where rapid door removal is crucial for efficient access, quick-release concealed hinges are essential. These hinges come in various styles, differing in pin type, hinge length, and strength to suit different needs.
Typically, quick-release concealed hinges are surface-mounted, allowing easier access to the pin for removal without the hassle of maneuvering around a door.
Besides the type, concealed hinges are chosen based on various specifications and features.
Cup concealed hinges come in various sizes, with each size tailored to specific applications.
The attachment method describes how the hinge arm connects to the mounting plate. The two primary types are clip-on and slide-on.
A concealed hinge with a clip-on design simplifies the process of attaching and removing doors. This feature is particularly beneficial for doors with multiple hinges, as it enables the installation of the door in a single action without the need for screws or screwdrivers.
A standard clip-on hinge features a clip tab positioned at the rear end of the hinge arm, adjacent to the depth adjustment screw. When the hinge arm is aligned with the mounting plate, the clip-on mechanism secures both components together. To detach the assembly, simply press or pull the clip tab.
The traditional method for attaching concealed hinges involves slide-on hinges. These hinges feature a straightforward design with a slot or notch on the hinge arm and a corresponding hole on the mounting plate. The hinge components are secured together using a fixing screw.
In the slide-on hinge design, the slot not only facilitates the attachment of the hinge arm to the mounting plate but also allows for depth adjustment of the hinge.
Typically, manufacturers offer a chart to guide the selection of the appropriate number of hinges. This number is influenced by the door's height, weight, and occasionally its width.
For instance, a door that is 40 inches (101.6 cm) in height generally needs two hinges. For every additional 20 inches (50.8 cm) in height, an extra hinge is recommended. Therefore,
This holds true regardless of the door's weight.
For weight considerations, a door weighing 15 pounds (6.8 kg) typically needs two hinges. Every additional 15 pounds (6.8 kg) usually requires an extra hinge. This guideline applies regardless of the door's height. It's important to note that this 15-pound threshold can vary based on hinge design, material, and thickness. The weight specification often varies more significantly than height in product datasheets.
When both height and weight suggest different hinge quantities, always use the higher number to ensure adequate support.
The method by which the door closes on its own, without needing additional external force, can be categorized into three main types: self-closing, soft-closing, and free-swing.
True to its name, a self-closing concealed hinge ensures that the door closes on its own and remains securely shut. This functionality is achieved through a mechanical design in the hinge arm, which incorporates a small spring mechanism. This spring is engineered to return the hinge to its closed position when the door is opened to a specific angle, preventing the door from remaining ajar due to insufficient torque or force.
The closing action is activated at the "tipping point" of the hinge arm, typically when the door is partially open at an angle between 10 and 20 degrees.
This concealed hinge incorporates a hydraulic damping mechanism. When the door is partially open and beyond the tipping point, the damper engages to close the door gently and quietly. This mechanism prevents sudden slamming, which could damage the furniture. The damper provides considerable resistance, making it difficult to force the door shut. While the soft-closing feature is a type of self-closing design, it includes additional technology for enhanced performance.
Certain soft-close mechanisms offer adjustable damping or resistance settings. This allows the damping system to be configured for either a higher resistance with a slower closing action or a lower resistance with a quicker closing action.
Free swing concealed hinges are the most straightforward of the three types. They lack a self-closing mechanism, allowing the door to swing open freely across its full range without encountering resistance or a tipping point. Doors equipped with free swing hinges rely on magnetic or mechanical latches to ensure they stay closed.
This specification refers to the angle between the door and the cabinet frame when the door is fully open. It is sometimes referred to as the range of opening or door swing.
Concealed hinges typically provide a minimum opening angle of around 100°. Hinges with angles less than 100° are classified as low angle types. Most standard concealed hinges offer an opening range between 100° and 120°. Hinges that allow opening beyond 120° tend to be more expensive due to their complex hinge arm mechanisms. The maximum opening angle available is 270°, enabling the door to swing fully back against the cabinet.
Adjusting this screw shifts the hinge arm’s position left or right when facing the cabinet door. This adjustment impacts the reveal, which is the part of the cabinet frame visible for frameless cabinets. In the case of two-door cabinets, it also alters the gap between the doors. Typically, the lateral adjustment provides a range of about 5 mm of movement.
Adjusting the lateral position can be challenging during the installation of concealed hinges, often exposing imperfections in the furniture structure. Fortunately, this adjustment is mechanical and can be done gradually by turning the screw. When adjusting one hinge, it's essential to coordinate with the other hinge on the door to achieve a balanced tilt. Excessive adjustment may cause the door to appear misaligned or sag on one side.
Adjusting the depth screw changes the door's position relative to the cabinet, moving it inward or outward. This adjustment helps manage the gap between the cabinet frame and the door's backside when the cabinet is closed.
Depth adjustment is commonly achieved through an elongated slot or notch near the back of the hinge arm, aligning with a hole on the mounting plate. By loosening the fixing screw on the plate, the hinge arm can slide forward or backward, allowing for 3 to 5 mm of adjustment. Advanced systems, such as Blum’s Spiral Tech, offer a different approach. Instead of using a fixing screw, these designs adjust the depth by rotating the adjustment screw a set number of turns. For example, Spiral Tech permits up to 5 mm of movement with just one and three-quarter turns of the screw.
The height adjustment capability of a concealed hinge enables vertical repositioning of the door. This adjustment is essential for aligning the top and bottom edges of the door with the corresponding edges of the cabinet, ensuring a proper fit.
The height adjustment mechanism is built into the mounting plate. Many designs include elongated slots on the plate that align with holes in the cabinet edge. By loosening the fixing screws, you can slide the mounting plate up or down slightly. This adjustment is usually minimal, typically ranging from 2 to 3 mm.
There are two primary types of mounting screws used for both the hinge cup and the mounting plate:
This is the traditional style of mounting hinge. As the name suggests, it uses screws to fasten the hinge onto the door and side or frame of the cabinet.
This feature was designed to simplify the installation process of concealed hinges. Hinges equipped with this capability have pre-fitted dowels built into the hinge assembly, allowing for tool-free installation by simply pressing the dowels into the holes in the cabinet.
Concealed hinges are typically made of stainless steel. Stainless steel has excellent mechanical properties, a variety of surface finishes, and inherent corrosion resistance. Other materials used for fabricating concealed hinges are nickel-plated steel, galvanized steel, and brass.
Here is additional guidance for specifying concealed hinge requirements. It is advisable to consult charts and tables that detail these values for accurate and precise mounting.
The door gap refers to the space between the edge or frame of the cabinet and the backside of the door. Ideally, a small door gap is preferred for a seamless look. However, if the gap is too small, it may cause the door to clash or scrape against the cabinet. The standard door gap is usually 3/16 inches (4.8 mm), but it can be adjusted using the depth adjustment screw.
The bore is the cavity in the door designed to accommodate the hinge cup. To determine the bore distance, measure from the edge of the door to the perimeter of the bore. This measurement, combined with the thickness of the mounting plate and the hinge crank, helps in achieving the desired overlay.
Datasheets for concealed hinges often provide specifications for mounting plate thickness. Selecting the appropriate thickness, in conjunction with the bore distance, is crucial for achieving the desired overlay. Standard mounting plate thicknesses typically range from 0 to 9 mm. A 0 mm thickness does not imply the absence of a mounting plate but indicates that the hinge does not affect the overlay reduction.
The hinge crank denotes the amount of offset in the hinge arm, which can be directed either to the left or right, resulting in positive or negative values. Similar to mounting plate thickness, the hinge crank influences the final overlay. A hinge arm with a zero crank is neutral or flat, corresponding to a full overlay hinge. The range for hinge crank values typically extends from -3 mm to +19 mm.
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