A stamping die is a unique precision tool, which is used to cut metal sheet and form it into a particular shape. Dies contain cutting and forming sections that are usually made from special hardenable steel, known as tool steel. These cutting and forming sections can also be made from different hard wear-resistant materials, like carbide.
Stamping is a cold-forming process, in which heat is neither used on purpose into the die nor the sheet. However, since the cutting and forming process entails friction, which in turn generates heat, stamped parts that leave the dies are often very hot. Dies used in making microelectronics are available in a variety of sizes, some small enough to fit your palm, while others can reach 20 square ft by 10-ft. thickness and can, therefore, be used in making the sides of an automobile body.
Types of Dies
There are different types of stamping dies, and all perform any of the two basic operations of cutting, forming or both. There are robotically-loaded line dies, manually-loaded line dies, fully-automated progressive dies and fully-automated transfer dies.
The operation most commonly done in a stamping die is cutting. To cut off the metal, it is placed between 2 bypass tool steel sections with a small gap in between them, which is also referred to as the cutting clearance.
Cutting clearance can vary, depending on the type of cutting operation done, properties of metal and the preferred edge condition of the part. Usually, the cutting clearance is expressed in terms of metal thickness percentage. The cutting clearance most commonly used is approximately 10% of the metal’s thickness.
There are several different cutting operations that come with their own distinct function. The most common are as follows:
The external perimeter of the flat sheet metal is cut off to give the desired shape to the piece part. The excess is usually discarded as scrap.
Notching, which is often associated with progressive dies, is a process wherein cutting is done progressively on the outer part of a sheet metal strip to produce a given strip profile.
Blanking is a double-purpose cutting operation often done on a larger scale. It is used in operations where the slug is kept for more pressworking. At times, it is used to sever finished piece parts detached from the sheet metal. The shaped sheet metal slug taken out from the sheet through this process is known as the blank, a piece of sheet metal that can be later cut or formed.
Piercing, also called perforating, is an operation wherein metal is cut to produce a round, square or specially-shaped hole in a formed part or flat sheet metal. Piercing is different from blanking mainly because the slug is removed as scrap in piercing, while the slug is used in blanking. The cutting punch that creates the hole is known as the pierce punch and the hole is called the matrix.
Lancing is the process of slicing or slitting the metal to free up metal, but not separate it from the strip. Lancing is usually performed in progressive dies to produce a part carrier known as a flex or stretch web.
Since shearing cuts or slices the metal along a straight line, this method is commonly used for creating square and rectangular blanks.