Before sheet metal can be cut into desired sizes, sheet metal manufacturers are responsible for bending and molding the metal materials into specified forms by applying very carefully calculated amounts of force. This process is known as sheet metal forming, or sometimes called metal bending, and can involve many different techniques and pieces of equipment. Below is a basic introduction to the most commonly used methods of sheet metal forming .
Sheet metal bending, as its name would imply, involves bending the metal around an axis. There are many different factors that can make one bend unique from another, including the placement of the axis, the angle, the length, and the thickness. A bend with a larger bend radius and angle, for example, will have a bend that has more of a gradual curve as opposed to a tighter, more confining bend. Bending is generally accomplished using a piece of equipment known as a press brake, which uses a tool called a punch to apply specific amounts of pressure, using a hydraulic ram, to the sheet metal. The amount of force, as well as the depth used, enables the manufacturer to achieve the desired bend in the metal.
Roll forming shapes sheet metal by applying multiple bending techniques using rollers. The sheet of metal goes through several different rolling stations, and each station has a roller of a different shape and/or size. As the rollers are forced over, under, or on the sides of the metal, the metal is manipulated into the desired shape due to the pressure created. Roll forming can be used to achieve many different varieties of sheet metal parts.
Stretch forming involves securing the edges of the metal sheet while a form die hydraulically lifts the center of the sheet, thus stretching and bending the metal. A form die is simply the name of the block that is pressed into the metal, and can be different sizes depending on the radius needed. Stretch forming is generally used to create parts that require large, smooth, and precise curves.
Spinning, or spin forming, is a technique used to create round parts from sheet metal. The metal is spun quickly on a spindle, while a tool places pressure from one side, causing the metal to take on a cylindrical shape. The placement of the pressure dictates the diameter of the part, but the result is typically a hollow, symmetric and round shape. Click here for more information.