Friction hinges’ characteristic duality of fluid motion and angle retention sets them apart from other hinge varieties. Friction hinges are valued because they can be opened and closed easily even though they rigidly retain their angle of openness when not in motion. Laptop screens, movable vehicle sun visors, portable DVD player screens and many other hinged, planar objects would not be useful if they could not be positioned according to the needs of their users.
Other hinge designs like simple butt hinges or even continuous hinges would not be appropriate for use in such products; a laptop computer fitted with a butt hinge would slam closed unless propped up by something. Friction hinges can also be used in some building door applications. They can be especially useful in loading docks and other settings in which a continuous stream of traffic passes through a doorway.
Friction hinges are alternately known as “constant torque hinges,” which is descriptive of the mechanism of a friction hinge’s operation. Torque is the measure of the force necessary to cause an object to rotate. In very basic terms, friction hinges require more torque to rotate than do most other hinges, but they do not require so much torque that they are difficult to rotate.
While friction hinges offer many benefits not offered by other hinge varieties, friction hinges fail more easily and sooner than simpler hinges. The frequent opening and closing of friction hinges can wear down the inner mechanisms that create friction, eventually to the point where they are not usable. In recent years manufacturers and researchers have investigated ways to slow the aging process of friction hinges.
Especially as laptop computers become more affordable, demand for sturdy friction hinges has risen. Some manufacturers have developed friction hinge products that are protected by guarantees, which indicates that friction hinge improvement efforts are advancing.