This article will take an in depth look at friction hinges and their applications.
In this article we will discuss topics such as:
A friction hinge offers resistance to the pivoting action of a hinge, enabling it to manage or maintain the movement of items as they open and close. Commonly known as free motion, positioning, torque, or free stop hinges, they ensure a specific tolerance between mechanical components.
Operating through torque generated by applying certain force levels, friction hinges introduce additional resistance via lubricants or springs. Often installed on both sides of a door or window, these hinges don't force the door or window to fully open or close but instead allow them to maintain a stable, fixed position.
Friction hinges are designed to hold their position for extended periods, customizable to meet specific needs, such as one-way or two-way classification. One-way hinges resist motion in one direction, whereas two-way hinges dampen movement in both directions. Moreover, friction hinges can be tailored to combine one-way and two-way resistance in a single unit, with customizable viscosity, temperature tolerance, and resistance attributes.
Both pragmatic and secure, friction hinges are ideal for machinery and equipment applications. They might also integrate additional features, such as lift assistance, to minimize the effort required for use.
The friction or torque strength of these hinges can differ based on their type, design, and internal makeup. Each torque hinge generally comes with a specified range of torque strength, characterized by a tolerance noted as plus or minus (±). Recognizing the torque or friction strength that a hinge can deliver is vital for its peak performance.
For efficient functioning, the torque strength of friction hinges should ideally be close to the lower end of their defined range. If the torque or friction surpasses this limit, the hinges might not provide a free stop nor sustain a fixed position unaided. On the contrary, if the torque strength is excessively high, the movable parts might become too rigid and hard to adjust.
Hinges are typically made from metal to ensure durability and stability. When choosing a hinge, it's essential to select the right metal to meet the specific requirements of the application where the hinge will be used.
Metals differ in terms of hardness, corrosion resistance, rust resistance, strength, and appearance. These factors are crucial for all hinges, but for friction hinges, durability and strength are particularly important. This is because a friction hinge must support the weight of a window or door, which can range from 1 to 10 pounds (0.45 to 4.5 kg), while in the open position.
Key considerations when selecting a friction hinge include:
The metal used to produce a friction hinge determines where it can be applied, so this material needs to be ascertained early on. Many different metals are used in the production of friction hinges, with cold rolled steel, stainless steel, aluminum, bronze, and brass being the most common.
Cold rolled steel is an iron alloy processed at room temperature without the application of heat. This cold rolling method preserves the metal's robust physical properties, resulting in friction hinges that are strong, durable, and long-lasting.
“Stainless steel” denotes a group of alloys composed primarily of iron, with at least 2% carbon and chromium. The key feature that sets stainless steel apart from other metals is its chromium content, which reacts with oxygen in the air to form a protective layer of oxidation.
The proportions of chromium and carbon vary depending on the stainless steel grade. These variations affect the steel's properties, enhancing its resistance to corrosion, temperature fluctuations, and improving its weldability and formability. Two commonly used grades of stainless steel for manufacturing friction hinges are Grade 316 and Grade 18-8.
In addition to its inherent corrosion resistance, aluminum offers several properties that make it an excellent choice for friction hinges. Notably, its exceptional strength-to-weight ratio surpasses that of many other metals. The lightweight nature of aluminum also facilitates easier installation and removal.
Regardless of its light weight, aluminum has the same durability and strength as heavier metals. Aluminum hinges can withstand the required weight of connected doors and windows without cracking or experiencing strain damage.
Brass is an alloy of zinc and copper. Modern brass is a combination of 67% copper and 33% zinc, with a 2% lead content to improve its machinability. Much like aluminum, stainless steel, and copper, brass is resistant to the effects of corrosion from saltwater, making it an ideal solution for friction hinges for boats.
Bronze hinges are known for their strength, outstanding ductility, and resistance to corrosion. They can endure friction from other metals without deteriorating. Additionally, bronze hinges offer an attractive aesthetic, which contributes to their higher cost compared to other types of friction hinges.
Steel, an alloy composed of iron, carbon, and trace elements, is renowned for its strength, durability, and long lifespan. Due to its widespread availability, steel hinges are generally more affordable than those made from other metals. Consequently, steel hinges are used in a diverse range of applications and settings.
Different types of steel include:
When exposed to oxygen, titanium forms a protective titanium oxide layer on its surface. This oxide layer provides resistance to chemicals, corrosion, and rust, while offering impressive strength-to-weight and strength-to-density ratios. Certain grades of titanium have tensile strength comparable to steel but are significantly lighter.
Titanium is widely used in aerospace applications due to its exceptional strength and low density. Various grades of titanium exist, each with unique properties and suitable for different applications.
Friction hinges, also known as torque or position control hinges, use an internal mechanism to create friction, which resists their pivoting motion. These hinges are designed to keep lids, doors, panels, displays, and windows securely in place for convenient access.
The movement of a friction hinge is smooth and requires minimal effort. Their design ensures firm positioning, preventing issues like springback, hard slamming, or unexpected closure of doors, windows, or other objects. This capability not only protects objects and people but also facilitates easy and safe access to equipment.
When a friction hinge is operated, it generates a rotational force that creates friction, acting as a stopping mechanism. The three primary types of friction produced by a friction hinge are curl, disk, and pipe.
Curl friction is created by a spring steel sheet wrapped around a shaft, which generates friction through its material properties. Spring steel is known for its ability to return to its original shape without deformation. Like disc and pipe friction mechanisms, the curl friction structure is housed within the hinge.
Disc friction occurs between rotating disc-shaped components and stationary, fixed surfaces. The stationary surface creates resistance against the motion of the rotating discs, generating friction.
Pipe friction involves connecting tightly fitting parts through friction to form a durable and precisely aligned bond. In a friction hinge, this type of friction is achieved by forcing the shaft through the knuckles of the hinge.
Torque is the force responsible for the friction mechanism that keeps a door, panel, or window open. The torque provided by a friction hinge must be adequate to match the weight of the object it supports.
When choosing a friction hinge, it's important to calculate both the maximum torque that the door or flap will exert and the maximum torque that the hinge can handle. To determine the torque exerted by the door, panel, or flap, multiply the weight of the object by the distance from the rotation center to the object's center of gravity.
These torque calculations typically assume that the door is flat; however, some doors may have complex shapes, such as “L” shapes, which can affect the torque measurements.
The lifespan of a hinge is determined by how often it opens and closes, based on the application's expected usage. With the right materials and correct choice, a friction hinge can last throughout the application's lifetime.
A well-chosen hinge will maintain the necessary torque to perform efficiently and smoothly over a long period.
Dynamic torque refers to the resistance encountered during the hinge's rotation. For optimal performance, this resistance must be maintained in good condition.
Static torque is the resistance that occurs when a friction hinge is rotated. It keeps the door or flap in place and needs regular monitoring to ensure it maintains the desired position.
Springback is the tendency of a hinge to return to its original position once the applied force or friction is removed.
Free play denotes the movement in a friction hinge before adequate torque is achieved. It allows adjustment of a door, flap, or panel to the desired position. Excessive free play can be problematic if insufficient torque causes the door to close due to lack of friction. Manufacturers provide details about the free play in their hinges.
The visual appeal of a friction hinge is important for visible applications, such as display units, product lids, or kitchen cabinet doors. For many friction hinges that are not visible, appearance is less of a concern. For instance, laptop hinges are designed to blend seamlessly with the computer's casing and are compact.
Choosing a friction hinge for harsh or corrosive environments depends on its material composition. Hinge materials should resist acids and corrosive agents. Manufacturers provide guidelines on the material and suitable environments for their hinges.
There are countless ways to design and engineer hinges to fit specific friction hinge applications. From kitchen cabinets and laptops to industrial uses like electrical enclosures and machine covers, friction hinges are versatile. Manufacturers collaborate with clients to tailor hinges to precise needs and applications.
When selecting a friction hinge, these features should be taken into account. The adaptability and flexibility of friction hinges make them ideal for applications requiring precise control of openings.
Friction hinges are available in various sizes, shapes, and torque levels, each suited for specific functions. Their distinctive and versatile characteristics make them ideal solutions for doors, flaps, panels, or windows.
The three prevalent types of friction hinges are one-way, detent, and adjustable. These hinges are designed to offer support and ease of use, ensuring both protection and convenient access for users.
For all friction hinges, torque is crucial for maintaining the position of an open device. In a one-way friction hinge, consistent torque is applied in only one direction, with no torque affecting the reverse movement.
One-way friction hinges facilitate the opening of lids, devices, panels, doors, or displays, but they can make closing these items more challenging. This feature is particularly useful for managing large or heavy doors.
Detent friction hinges offer the advantage of keeping an opening securely closed to prevent springback and maintain the position of connected objects. Once a door or opening is set, it stays open and fixed in place. Unlike conventional hinges that allow for unrestricted movement, detent friction hinges restrict motion and keep the door or opening stationary, eliminating any potential for repositioning.
Similar to other hinges, detent hinges consist of two leaves and a connecting knuckle. The key feature that sets them apart is an embedded spring that applies force to secure the door or opening in its set position. When installed correctly, detent friction hinges address concerns about a door or opening moving or closing unintentionally.
Adjustable friction hinges allow for torque adjustment by turning a screw that rotates 180° at the top of the hinge shaft. Often called position control hinges, they offer the flexibility to define and modify the movement, operation, and placement of a panel or door. These adjustments can be made without incurring extra costs or requiring additional hardware or installations. Furthermore, adjustable friction hinges can be designed with concealed mountings for a sleek appearance.
For applications requiring a hinge that maintains its position despite applied force, a friction torque positioning hinge is the preferred choice. These hinges, sometimes known as free stop hinges, enable a lid or top to stay at a set angle.
Friction hinges can be customized with varying torque levels to suit specific needs, providing torque in any direction.
Friction stay hinges are variable torque hinges designed for security and safe operation of windows. They are adjustable hinges mounted on a slide to allow controlled movement of windows.
Standard Friction Stay Hinges are the most common and are used in most windows. They are designed in a way such that the movement of the window is restricted and controlled. These are used in storm-proof casement windows and uPVC flush windows.
Top hung friction hinges feature a handle at the bottom of the window, with the friction hinge positioned at the top. The window opens from the bottom, with the hinge providing a springback mechanism to aid in the opening process. Windows equipped with top hung friction hinges are pushed outward from the bottom.
Top hung hinges are adjustable in size to fit different window dimensions, ranging from 8 to 24 inches (20 to 61 cm). They are typically made of stainless steel with a thickness between 0.1 and 0.2 inches (2.6 to 3 mm). These hinges are suitable for use with both double-glazed and aluminum windows.
Side hung friction hinges are engineered to allow a window to open in a manner similar to a door. The handle is located on the side of the opening, with the hinges positioned at either the bottom or top. This design enables the window to open from the side like a door or from the top like a hatch.
Torque or friction hinges are sometimes referred to as constant torque hinges, where the leaf and pin maintain the hinge in a fixed position. These complex, specially-designed hinges come in a wide variety of configurations, each tailored to meet the specific needs of various applications.
Among the many types of friction hinges, the constant torque hinge is the most fundamental. It can be opened to any position and will hold that position until a sufficient force is applied, unlike other models that are designed to remain at a preset angle.
The SB-188 series offers a torque range from half an inch-pound to 14 inches-pound. It is commonly used in medical equipment, small LCDs, lids, covers, and safety guards.
The ZE-188 model series features both balanced and unbalanced torque configurations, available in right- and left-hand versions. It offers torque ranges from 1 to 8 inches-pound, with a slim profile and robust mounting geometry.
The ZC-188 series friction hinge offers a torque range from 3 to 8 inches per pound and features a closed housing. Similar to the ZE-188, it comes in both balanced and unbalanced torque configurations. It is constructed from various materials depending on the manufacturer and boasts a 30,000-cycle lifespan.
The SB-200 series provides a torque range from 3 inches per pound to 20 inches per pound or more. It is commonly used in headrests, medical devices, lids, covers, and LCDs. The SB-200 series hinge offers high torque in a compact design.
The ZC-250 series offers a torque span ranging between 5 inches and 17 inches per pound. This series features a uniquely coined and bent shaft design. It boasts a durability of up to 30,000 cycles and allows for continuous 360° rotation, holding its position precisely at any point during the rotation.
The ZE-375 series features a torque range from 10 inches per pound to 120 inches per pound, depending on the specific model. It offers options for either one-way or centralized torque configurations and can accommodate both left- and right-hand openings. This series is commonly employed in applications such as arm supports, headrests, medical apparatuses, lids, and covers.
The SB-500 series offers various torque ranges tailored to different hinge models, spanning from 20 to 70 inches per pound. This series finds applications in medical equipment, LCD screens, headrests, and arm supports. The SB-500 hinges are known for their compact size while delivering a robust torque range.
The MA-685 series friction hinges offer outstanding holding torque and adjustability. Featuring a 360° rotation hollow tube shaft, these hinges can pivot and remain securely in any desired position without backlash. The torque range for the MA-685 series varies from 25 to 100 inches per pound, providing balanced and symmetrical torque capabilities.
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