Hinges

View A Video on Hinges - A Quick Introduction

Because there are so many contexts in which hinges are used, a wide variety of hinge configurations and compositions exists to accommodate them. Butt hinges are among the most simple hinge varieties, followed closely by continuous hinges, which are also known as piano hinges. Continuous hinges are simply extended butt hinges. They are often used to create movable joints in tool boxes and other small containers as well as larger joints between panels in pianos. Strap hinges are characterized by their length; some strap hinge varieties are designed to extend across the entire widths of the doors to which they are affixed. Spring hinges can be simple or complex. In either case, a spring hinge is used to improve or impede the motion of two joined planes. Heavy duty hinges, many of which are weld on hinges are characterized by their high performance and high load bearing capacity. All of these hinges range in terms of their composition from aluminum, which is used in light-duty hinge applications, to stainless steel, which is prized because of its strength and rust-resistance.

The most basic hinge configuration is the butt hinge. The creation of a butt hinge begins with two plates, which are called leaves. Each leaf is machined on one of its edges; at the end of that machining process, the machined ends can interlock with each other like fingers. Those fingers are then curled by machinery into a circular shape. Those circular shapes are called knuckles. The plates are then aligned so that their knuckles align, and a removable or permanent pin is then inserted, joining the two leaves and forming the hinge. The leaves may already be drilled with holes for fasteners, or they can be drilled after the hinge has been formed. The latter option is more likely in specialized applications. Hinge designers intentionally create gaps between knuckles and between leaves; these gaps are called "end play." End play gaps reduce friction and make hinge movement easier. Once this process is complete, butt hinges can be affixed. In some cases, when used as door hinges, butt hinges cannot be directly affixed to doors and door frames. Often a mortise, which is a recession in the shape of the hinge, must be bored into the door, its frame or both. 

After butt hinges, the long list of possible hinge configurations becomes more complicated in terms of design and composition. Spring hinges can be complex in their design, or they can be very simple; the most simple spring hinge varieties are the same as butt hinges except for the addition of a coil wound tightly around the hinge's pin. The tendency of the coil is to uncoil itself, which pushes the leaves of the hinges toward or away from each other. More complex spring hinge designs can involve multiples coils, concealed coils and a host of other options. Continuous hinges can also be fitted with springs, as can be the case when they are affixed to containers. Weld on hinges are often appropriate for the suspension of very heavy doors. Heavy duty weld on hinges can be designed to bear door weights between a few hundred pounds and as much as 20,000 pounds. Such heavy duty hinges can be used in blast doors and bank vaults. In other cases, weld on hinges can be used in lighter-duty settings, particularly as components in wrought iron gates. In such cases, the welds can be painted, which allows for the hinge to reach certain levels of visual appeal.

Friction hinges are among the most advanced hinge varieties; they simultaneously allow for fluid motion and movement resistance. Friction hinges make possible the easy movement of a door, container cover or other planar object when that movement is desired, and they impede movement when it is not desired. Friction hinges are on the forefront of hinge development efforts; as portable electronics proliferate and become less expensive, demand for highly functional friction hinges rises. In laptop computers and in many portable video players, friction hinges are relied on to maintain screen positions as well as to conduct electrical components through their mechanisms. Historically, friction hinges have not been known for their long operating lives or for their durability; with constant use, the friction generating materials within the hinge wear down, rending the hinge unusable after a point. Recent advances and ongoing research in friction hinge technology have already produced reliable hinges in large volumes, and the failure rate associated with early friction hinges is becoming a thing of the past.

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Hinge Types

• Ball bearing hinges are used for high frequency and indoor applications and on doors with closers.
  
• Bronze bearing hinges are suitable for outdoor or other harsh environments.
  
• Butt hinges are secured to the door and the door frame. Swinging doors are one common application for which butt hinges are used.
  
• Cabinet hinges must be made from a strong, heavy material to prevent unevenness of cabinet doors.
  
• Continuous hinges, or "piano hinges," are longer than standard hinges, usually measuring five inches in length or more. Continuous hinges provide consistency in strength along the entire length of the hinge, supporting the objects to which they are attached and reducing the gap between objects and hinges.
  
• Door hinges are used on a variety of doors in personal, office and industrial settings.
• Friction hinges are hinges that simultaneously allow fluidity of motion and rigidity of position for the objects they join.
• Gate hinges are used on gates and entryways. In addition to standard manual hinges, gate hinges are commonly automatic for convenience and protection.
  
• Heavy duty hinges are characterized by their high performance and load bearing capacity.
• Multiple pin hinges have more than one pin and are used for double action.
  
• Panel hinges are designed for use with doors that are set flush into a frame.
  
• Plain bearing hinges are used in a wide variety of applications that require low to moderate usage.
  
• Plastic hinges are beneficial because they do not require lubrication, do not rust and remain silent and are more cost-effective than hinges made of metals, including stainless steel hinges. Most plastic hinges are also ultraviolet (UV), chemical and heat resistant.
  
• Spring hinges are used on entryways requiring automatic closure. Spring loaded hinges can also be configured to open automatically.
  
• Stainless steel hinges are useful in situations in which they are exposed to oxidation and corrosive substances because of the high corrosion resistance of stainless steel. Common applications in which stainless steel hinges are found include marine, oil/gas, petrochemical, chemical and pharmaceutical applications.
  
• Standard cutoff hinges have an even number of full knuckles. When the knuckle is facing up, a knuckle will be on the left end and a notch will be on the right end of the lower leaf.
  
• Stop hinges are designed to limit the movement of the leaves to a certain angle
• Strap hinges are a type of hinge with long straps that attach to the face of exterior and interior doors and cabinets while allowing for up to 180 degrees of swinging movement.
• Weld on hinges are smaller hinges that connect two separate metal parts, typically doors and door frames, without the use of knuckles.

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Hinge Terms

Back Angle - The angle of the hinges leaves, usually a minimum of 270, when the hinges are completely open.
 
Bent Pin - The pin found in hinges that contains a bent end to allow for easy removal of the pin. 

Both Leaves Half Swaged - When both of the leaves are swaged one half the pin diameter with a small space between the leaves when closed.

Closed - Refers to the position of the leaves of the hinges when they are parallel and together at the 0 position.

Coined Pin - A deformed end of a pin that causes the pin to be wedged into place when driven into hinges.
 
Crimped Ends - Hinges pins that can not be removed due to depression of the hinge knuckle.
 
Detent - A device that locks hinges in the open position.
 
End Play - The extent to which hinges leaves move axially.
 
Flat - Refers to the position of the leaves when they are at the 180 position.
 
Gauge - Hinges measurement reflecting the hinge leaf thickness.
 
Hinge Length - The measurement of hinges running parallel to the hinge pin from one end of the leaves to the other end of the leaves.
 
Hinge Width - Also known as "open width", it is the measurement of the width of hinges, including both leaves and the pin. Hinge width is a measurement perpendicular to the hinge pin.
 
Knuckle - Also referred to as joint, node, curl and loop it is the individual, hollow joint of a hinge through which the hinge pin is inserted.
 
Knuckle Length - The length of an individual knuckle, equivalent to one-half of the pitch.
 
Leaf - Component of hinges that extends laterally from the knuckle and revolves around the pin.
 
Leaf Width - The measurement from the pin to the end of the leaf. 

Lock Punch - Preventing leaf rotation by moving the material from adjacent knuckles to remove end play. It is located at the bottom of the knuckle in a uniform consistent pattern.

Offset - The process of decreasing leaf width through the formation of hinges leaves away from the hinge pin center. 

One Leaf Full Swaged - When one leaf is swaged equal to the pin diameter. Both are parallel while closed.

One Leaf Half Swaged - When one leaf is swaged one half the pin diameter.

Opposite Standardd Cutoff - When the lower leaf has a notch at the left end and 3 knuckles.

Paint Clearance - The amount of space between the knuckle and the edge of the leaf in every position of the hinge during operation.

Pin - The rod inserted through the hinge knuckles to hold the hinge in place.

Pitch - The measurement reflecting the distance between the opposite ends of two adjacent knuckles.

Plain Assembly - When the leaves aren't swaged and lay flat in the same plane in an open position.

Reverse Assembly - When the leaves aren't swaged and the opposing leaves extend laterally from opposite sides of the pin. The leaves don't close to a parallel position.

Reverse Swaged - When one leaf is swaged, as in reverse assembly, but the leaves will not close in a parallel position.

Side Play - The amount of leaf movement perpendicular to the pin. 

Spun Pin - Cold forming the end pins to a diameter larger than the inside portion to prevent axial movement. Mostly used for tamper-proofing.

Spun Ends - Hinge pin ends that have been peened, or flattened, in order to prevent pin removal. Although a pin with both spun ends is not removable, a pin containing only one spun end is still removable.
 
Staked Pin - A hinge pin that is not removable due to the staking of the hinge backside.

Standard Cutoff -  A hinge that has an even number of full length knuckles (plain assembly only).

Stop Hinge - A type of hinge intended to provide a limitation on the angle of the hinge leaves to a particular degree. 

Stop Hinge, Inside - When the leaves open to a stop angle.

Stop Hinge, Outside - When leaves move open positions and stop at a specific angle.

Swaging - A process of increasing hinge leaf width through the formation of the hinge leaf or leaves either toward or away from the hinge pin center.

Welded Pin - A type of pin in which the splined portion is slightly larger than the inside diameter on the curl of the pin. Welded pins are used in some slip joint hinges.

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