Overview

What is Stamping?

Stamping (also known as pressing) is the process of placing flat sheet metal in either blank or coil form into a stamping press where a tool and die surface forms the metal into a net shape. Stamping includes a variety of sheet-metal forming manufacturing processes, such as punching using a machine press or stamping press, blanking, embossing, bending, flanging, and coining. This could be a single stage operation where every stroke of the press produces the desired form on the sheet metal part or could occur through a series of stages. The process is usually carried out on sheet metal, but can also be used on other materials, such as polystyrene. Progressive dies are commonly fed from a coil of steel, coil reel for the unwinding of the coil to a straightener to level the coil, and then into a feeder which advances the material into the press and die at a predetermined feed length. Depending on part complexity, the number of stations in the die can be determined.

What is the process of Stamping?

Blanking:

When it’s necessary, blanking is always the first step in any metal stamping procedure. It involves the cutting of a large sheet or coil of metal into pieces that are smaller and more manageable. Blanking is usually necessary when a metal stamped part must be drawn or formed.

Piercing:

Anytime a finished part requires some type of holes, slots, or any other kinds of the cutout, the piercing will generally be included in the metal stamping process. Piercing can be accomplished in tandem with blanking, and it causes the required shapes to be punched out of the sheet-metal being used.

Drawing:

Drawing constitutes the actual stamping procedure in the overall metal stamping process. When a punch forces a metal section through a die, the primary shape of the part is determined. If the depth of the part must be less than the primary opening, it’s referred to as shallow drawing, and when the depth is greater then the part, it’s referred to as deep-drawn.

Bending:

As you might guess from its name, bending involves placing the work-in-progress part on a specially designed die, where a RAM pushes against the metal imparting the necessary bend. Bending is always done after drawing since trying to punch a piece which is already bent will almost always cause the whole part to be deformed.

Air bending:

Air bending is accomplished by having a punch bend the flat surface of a part into a die, which is generally V-shaped. The space between the die and the punch is generally wider than the thickness of the metal, which results in a bend that relaxes somewhat after the part has been released. Air bending uses significantly less pressure and power than other bending possibilities.

Bottoming and coining:

These two processes are very similar in their results to air bending, but they always use a great deal more pressure. Another difference between this method and air bending is that material is fully forced into a tight-fitting die, which causes a permanent bend to be applied to the part.

Forming:

Forming is another bending process that is very similar to bottoming and coining. The end result of forming is usually parts that have multiple bends, commonly U-bends, which are created all in a single step.

Pinch trimming:

In this process, a piece is cut from a section of sheet metal, so as to separate it from any scrap. It’s a somewhat unconventional process in which the metal is pinched up against a surface that is flat and vertical. Pinch trimming is generally used to cut deep-drawn circular cups from a sheet of metal.

Lancing:

Lancing is a process that is fairly unique and is used to make tabs or vents when cutting metal. One section of a part gets cut along three edges at the same time and is bent intentionally. This creates the necessary hook-like feature or opening while eliminating the need for a secondary machining step, or any kind of scrap collection.