Hinges are mechanical devices that bring two pieces of a window together so that they can swing open and shut. Most hinges are made of some type of metal; however, other hinge material includes plastic, leather or wood. Many window hinges allow the window to move in a limited arc, but some hinges allow for a 360 degree pivot.
A pivot hinge will generally be mounted at either the top or the bottom of the door, and they make either a right or rectangular angle. Pivot hinges are meant to be hidden, but a piece of the metal will be exposed on the inside and outside of windows. These types of window hinges may allow the window to move in a 360 degree pattern if installed to do so. Hinge sizes depend upon window size. These types of hinges come in a variety of metals, including steel, chrome and brass.
Two identical leaves that look similar to a butterfly comprise butt hinges. One part of this set will be buried into the window itself. The other piece will be drilled into the window frame or sash. This type of hinge allows the window to swing out, and these can be placed at the top, bottom or side of the window depending on use and move-ability. Butt hinges can come with or without removable pins or pre-drilled holes. Aluminium and stainless steel should be used on windows for their rust resistance. Butt hinges are most commonly used on security windows.
Casement hinges can either be concealed or exposed. The exposed hinges look similar to butt hinges, except that they generally have more holes. The concealed hinges have a straight line section with two pieces: one near the top and one near the centre of the straight line piece. The piece near the top will connect to the lower piece. Casement hinges allow windows to pivot about 90 degrees, and they will attach to the sash of the window. Steel, copper, brass and stainless steel are popular choices for this type of hinge. Casement hinges can also be used for awnings over windows.