Sheet metal Cutting Operation involves the separation of the metal of the sheet in certain areas. This separation is caused by shearing forces acting on the metal through the edges of the punch and die.
Cutting process that produces straight line cuts to separate a piece of sheet metal. Shearing is used to cut a sheet parallel or at any angle to an existing edge which is held square. Shearing is primarily used to cut sheet stocks into smaller sizes in preparation for other processes.
As explained in above image, blanking operation produces a enclosed part from large piece of sheet metal. As a result blank part is used as final product.
In another words, Blanking is a cutting process in which a piece of sheet metal is removed from a larger piece of stock by applying a great enough shearing force, the piece removed, called the Blank, is not scrap but rather the desired part.
Punching is a cutting process in which material is removed from a piece of sheet metal by applying a shearing force. Punching is similar to blanking operation except that the removed material is scrap. Punching can be used to produce holes and cutouts of various shapes and sizes.
Punching operations can be further classified into different categories:
Punching operation in which a rectangular tool makes a rectangular slot in sheet.
Lancing is a punching operation in which the work piece is sheared and bent with one strike of the die. This operation is used to make tabs, vents, and louvers. Normally lancing is done on a mechanical press.
Nibbling process cuts a contour by a series of overlapping punches. Complex shapes can be cut in sheet metal using simple tools (round or rectangular punches) with nibbling process.
For example, Combinations of series of punches of small diameter (2mm) we can make round hole of larger diameter (20 mm)
This process is used where making dedicated blanking die cannot be justified due to low production volumes.
Perforating is a punching operation that involves punching a large number of closely spaced holes.
As explained above, Piercing operation produces extruded hole or slot. As a result of applied force from piercing tool, sheet metal starts tearing and produces extruded hole/slot.
In another words, Piercing is combination of cutting and forming operation.
Notching is a piercing operation that removes material from the edge of the work piece.
The trimming operation is the last operation performed because it cuts away excess or unwanted irregular features from the work piece.
Deburring process is a finishing operation where a small amount of metal is removed away from an already blanked part to remove all sharp edges and corners and make the blank smooth.