Stamping / progressive die drawing

Progressive die drawing, or stamping, is a forming process that utilizes a series of stamping stations to perform simultaneous operations on sheet metal. The final metal workpiece is developed as the strip of metal is processed through the stamping die.

The progressive die stamping process characteristics include:

• The utilization of multiple cutting and/or forming operations simultaneously,
• Excellent suitability to produce small workpieces at a rapid rate,
• The necessity to invest in expensive die sets,
• The ability to save time and money by combining forming operations,
• The capability to maintain close tolerances, depending on the tools.

The illustration that follows provides a two-dimensional look at a typical progressive die metal drawing process in two steps – one open die and one closed die.

As the metal strip is moved through the drawing process, it is exposed to a series of progressive die stations, each one changing the metal configuration left on the metal by the previous station. Therefore, the metal workpiece is created in a series of stamping stages.

The second illustration shows a closed die with the finished component workpiece falling out of the die on the lower right hand side.

The overview on the top of the second illustration shows a "birds eye" view of the metal strip as it is going through the dies.

During the drawing operation, punches in the die can perform cutting, forming, and drawing operations to produce the needed component.

Normally, this process is limited to shallow draw stamping. A related process, deep draw stamping, allows the metal to be drawn more deeply, often to a ratio of 7 or 8 to 1.

Tooling in progressive die drawing is complex and relatively expensive.

Common materials progressively drawn include:

• Aluminum
• Brass
• Cold rolled steel commercial steel
• Cold rolled draw steel
• Cold rolled stainless steel

View an overview of metal stamping services any of the metal forming processes offered by Advantage Fabricated Metals, or view a full table that matches the metals to the metal fabricating services we offer.

For more information about Advantage Fabricated Metals and the metal fabricating services we provide, please fill out our contact form or call us at 1-815-323-1310.

Stamping Machine for Automotive

Stamping is a metalworking process by which sheet metal strips are punched using a press tool which is loaded on a machine press or stamping press to form the sheet into a desired shape. This could be a single stage operation where every stroke of the press produce the desired form on the sheet metal part, or could occur through a series of stages. The process can also be used on other suitable materials, such as polystyrene plastic.

The most common stamping operations are:

• Piercing
• Fine blanking
• Bending
• Forming
• Coining
• progressive stamping
• Deep Drawing
• Embossing
• Extrusion

Piercing is a shearing process where a punch and die are used to create a hole in sheet metal or a plate. The process and machinery are usually the same as that used in blanking, except that the piece being punched out is scrap in the piercing process.^[1] There are many specialized types of piercing: lancing, perforating, notching, nibbling, shaving, cutoff, and dinking.

The amount of clearance between a punch and die for piercing is governed by the thickness and strength of the work-piece material being pierced. The punch-die clearance determines the load or pressure experienced at the cutting edge of the tool, commonly known as point pressure. Excessive point pressure can lead to accelerated wear and ultimately failure.

Burr height is typically used as an index to measure tool wear, because it is easy to measure during production.

Fine blanking presses are similar to other metal stamping presses, but they have a few critical additional parts. A typical compound fine blanking press includes a hardened die punch (male), the hardened blanking die (female), and a guide plate of similar shape/size to the blanking die. The guide plate is the first applied to the material, impinging the material with a sharp protrusion or stinger around the perimeter of the die opening. Next a counter pressure is applied opposite the punch, and finally the die punch forces the material through the die opening. Since the guide plate holds the material so tightly, and since the counter pressure is applied, the material is cut in a manner more like extrusion than typical punching. Mechanical properties of the cut benefit similarly with a hardened layer at the cut edge from the cold working of the part^[1]. Because the material is so tightly held and controlled in this setup, part flatness remains very true, distortion is nearly eliminated, and edge burr is minimal. Clearances between the die and punch are generally around 1% of the cut material thickness, which typically varies between .5-13mm^[2]. Currently parts as thick as 19mm can be cut using fine blanking^[3]. Tolerances between ±.0003"-.002" are possible based on material thickness & tensile strength, and part layout^[4].

With standard compound fine blanking processes, multiple parts can often be completed in a single operation. Parts can be pierced, partially pierced, offset (up to 75•), embossed, or coined, often in a single operation^[5]. Some combinations may require progressive fine blanking operations, in which multiple operations are performed at the same pressing station however.