Progressive stamping

Last updated
Progressive (punch and blanking) die with strip and punchings ProgressiveDieToyota-strip-scrap.jpg
Progressive (punch and blanking) die with strip and punchings

Progressive Die is a metalworking method that can encompass punching, coining, bending and several other ways of modifying metal raw material, combined with an automatic feeding system.

Contents

The feeding system pushes a strip of metal (as it unrolls from a coil) through all of the stations of a progressive stamping die. [1] Each station performs one or more operations until a finished part is made. The final station is a cutoff operation, which separates the finished part from the carrying web. The carrying web, along with metal that is punched away in previous operations, is treated as scrap metal. Both are cut away, knocked down (or out of the dies) and then ejected from the die set, and in mass production are often transferred to scrap bins via underground scrap material conveyor belts.

The progressive stamping die is placed into a reciprocating stamping press. As the press moves up, the top die moves with it, which allows the material to feed. When the press moves down, the die closes and performs the stamping operation. With each stroke of the press, a completed part is removed from the die.

Since additional work is done in each "station" of the die, it is important that the strip be advanced very precisely so that it aligns within a few thousandths of an inch as it moves from station to station. Bullet shaped or conical "pilots" enter previously pierced round holes in the strip to assure this alignment since the feeding mechanism usually cannot provide the necessary precision in feed length.

Progressive stamping can also be produced on transfer presses. These are presses that transfer the components from one station to the next with the use of mechanical "fingers". [2] For mass production of stamped parts which do require complicated in-press operations, it is always advisable to use a progressive press. One of the advantages of this type of press is the production cycle time. Depending upon the part, productions can easily run well over 800 parts/minute. One of the disadvantages of this type of press is that it is not suitable for high precision deep drawing which is when the depth of the stamping exceeds the diameter of the part. When necessary, this process is performed upon a transfer press, which run at slower speeds, and rely on the mechanical fingers to hold the component in place during the entire forming cycle. In the case of the progressive press, only part of the forming cycle can be guided by spring-loaded sleeves or similar, which result in concentricity and ovality issues and non uniform material thickness. Other disadvantages of progressive presses compared to transfer presses are: increased raw material input required to transfer parts, tools are much more expensive because they are made in blocks with very little independent regulation per station; impossibility to perform processes in the press that require the part leave the strip (example beading, necking, flange curling, thread rolling, rotary stamping etc.). [3]

The dies are usually made of tool steel to withstand the high shock loading involved, retain the necessary sharp cutting edge, and resist the abrasive forces involved. [4]

The cost is determined by the number of features, which determine what tooling will need to be used. Engineers keep the features as simple as possible to keep the cost of tooling to a minimum. Features that are close together produce a problem because it may not provide enough clearance for the punch, which could result in another station. It can also be problematic to have narrow cuts and protrusions.

Applications

A representative example of the product of a progressive die is the lid of a beverage can. The pull tab is made in one progressive stamping process and the lid & assembly is made in another, the pull tab simultaneously feeding at a right angle into the lid & assembly process. Also various car brake calipers have plates that are bent into shape, possibly cut too using these methods. [5]

See also

Related Research Articles

<span class="mw-page-title-main">Forging</span> Metalworking process

Forging is a manufacturing process involving the shaping of metal using localized compressive forces. The blows are delivered with a hammer or a die. Forging is often classified according to the temperature at which it is performed: cold forging, warm forging, or hot forging. For the latter two, the metal is heated, usually in a forge. Forged parts can range in weight from less than a kilogram to hundreds of metric tons. Forging has been done by smiths for millennia; the traditional products were kitchenware, hardware, hand tools, edged weapons, cymbals, and jewellery.

<span class="mw-page-title-main">Metalworking</span> Process of making items from metal

Metalworking is the process of shaping and reshaping metals in order to create useful objects, parts, assemblies, and large scale structures. As a term, it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale: from huge ships, buildings, and bridges, down to precise engine parts and delicate jewelry.

<span class="mw-page-title-main">Perforation</span> (Making) a small hole in a thin material

A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes collectively are called a perforation. The process of creating perforations is called perforating, which involves removing bits of the workpiece with a tool. Old-fashioned lick-and-stick postage stamps are perforated. When a tool makes small cuts in the material it is called 'rouletting', because that tool often resembles a roulette wheel, with blades around the edge. Raffle tickets are a good example of rouletting.

<span class="mw-page-title-main">Powder metallurgy</span> Process of sintering metal powders

Powder metallurgy (PM) is a term covering a wide range of ways in which materials or components are made from metal powders. PM processes are sometimes used to reduce or eliminate the need for subtractive processes in manufacturing, lowering material losses and reducing the cost of the final product. This occurs especially often with small metal parts, like gears for small machines. Some porous products, allowing liquid or gas to permeate them, are produced in this way. They are also used when melting a material is impractical, due to it having a high melting point, or an alloy of two mutually insoluble materials, such as a mixture of copper and graphite.

<span class="mw-page-title-main">Machine press</span> Machine tool that changes the shape of a work piece by the application of pressure

A forming press, commonly shortened to press, is a machine tool that changes the shape of a work-piece by the application of pressure. The operator of a forming press is known as a press-tool setter, often shortened to tool-setter.

A die is a specialized machine tool used in manufacturing industries to cut and/or form material to a desired shape or profile. Stamping dies are used with a press, as opposed to drawing dies and casting dies which are not. Like molds, dies are generally customized to the item they are used to create.

<span class="mw-page-title-main">Sheet metal</span> Metal formed into thin, flat pieces

Sheet metal is metal formed into thin, flat pieces, usually by an industrial process.

<span class="mw-page-title-main">Hydroforming</span> Method of shaping metal through pressurized water

Hydroforming is a means of shaping ductile metals such as aluminium, brass, low alloy steel, and stainless steel into lightweight, structurally stiff and strong pieces. One of the largest applications of cost-effective hydroforming is the automotive industry, which makes use of the complex shapes made possible by hydroforming to produce stronger, lighter, and more rigid unibody structures for vehicles. This technique is particularly popular with the high-end sports car industry and is also frequently employed in the shaping of aluminium tubes for bicycle frames.

<span class="mw-page-title-main">Punch press</span>

A punch press is a type of machine press used to cut holes in material. It can be small and manually operated and hold one simple die set, or be very large, CNC operated, with a multi-station turret and hold a much larger and complex die set.

<span class="mw-page-title-main">Punching</span> Creating a hole by forcing a tool through the workpiece

Punching is a forming process that uses a punch press to force a tool, called a punch, through the workpiece to create a hole via shearing. Punching is applicable to a wide variety of materials that come in sheet form, including sheet metal, paper, vulcanized fibre and some forms of plastic sheet. The punch often passes through the work into a die. A scrap slug from the hole is deposited into the die in the process. Depending on the material being punched this slug may be recycled and reused or discarded.

<span class="mw-page-title-main">Stamping press</span>

A stamping press is a metalworking machine tool used to shape or cut metal by deforming it with a die. A stamping press uses precision-made male and female dies to shape the final product. It is a modern-day counterpart to the hammer and anvil.

<span class="mw-page-title-main">Die cutting (web)</span> Pressing pre-formed tools into thin sheets to extract shapes

Die cutting is the general process of using a die to shear webs of low-strength materials, such as rubber, fibre, foil, cloth, paper, corrugated fibreboard, chipboard, paperboard, plastics, pressure-sensitive adhesive tapes, foam, and sheet metal. In the metalworking and leather industries, the process is known as clicking and the machine may be referred to as a clicking machine. When a dinking die or dinking machine is used, the process is known as dinking. Commonly produced items using this process include gaskets, labels, tokens, corrugated boxes, and envelopes.

<span class="mw-page-title-main">Stamping (metalworking)</span> Forming metal sheets with a stamping press

Stamping 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.

<span class="mw-page-title-main">Deep drawing</span> Metalworking process

Deep drawing is a sheet metal forming process in which a sheet metal blank is radially drawn into a forming die by the mechanical action of a punch. It is thus a shape transformation process with material retention. The process is considered "deep" drawing when the depth of the drawn part exceeds its diameter. This is achieved by redrawing the part through a series of dies.

Skiving or scarfing is the process of cutting material off in slices, usually metal, but also leather or laminates. Skiving can be used instead of rolling the material to shape when the material must not be work hardened, or must not shed minute slivers of metal later which is common in cold rolling processes. It can also be used to create fins on a block of metal, not shaving the part entirely off.

Hemming is a technology used in the automotive industry to join inner and outer closure panels together. It is the process of bending/folding the flange of the outer panel over the inner one. The accuracy of the operation significantly affects the appearance of the car’s outer surfaces and is therefore a critical factor in the final quality of a finished vehicle.

<span class="mw-page-title-main">Blanking and piercing</span> Shearing processes

Blanking and piercing are shearing processes in which a punch and die are used to produce parts from coil or sheet stock. Blanking produces the outside features of the component, while piercing produces internal holes or shapes. The web is created after multiple components have been produced and is considered scrap material. The "slugs" produced by piercing internal features are also considered scrap. The terms "piercing" and "punching" can be used interchangeably.

A punching machine is a machine tool for punching and embossing flat sheet-materials to produce form-features needed as mechanical element and/or to extend static stability of a sheet section. According to the file, Richard Walsh, the county of Grayson, and the State of Texas had invented and applied for US patent in 1894.

Press tools are commonly used in hydraulic, pneumatic, and mechanical presses to produce the sheet metal components in large volumes. Generally press tools are categorized by the types of operation performed using the tool, such as blanking, piercing, bending, forming, forging, trimming etc. The press tool will also be specified as a blanking tool, piercing tool, bending tool etc.

Today the metal forming industry is making increasing use of simulation to evaluate the performing of dies, processes and blanks prior to building try-out tooling. Finite element analysis (FEA) is the most common method of simulating sheet metal forming operations to determine whether a proposed design will produce parts free of defects such as fracture or wrinkling.

References

  1. DOE Workshop on Research and Development Needs for Bipolar Plates for PEM Fuel Cell Technologies (14 February 2017). "Bipolar Plate Cost and Issues at High Production Rate" (PDF).
  2. Occupational Safety and Health Administration (11 February 2022). "1910.217 - Mechanical power presses".
  3. BlechMal GmbH (11 February 2022). "Bleche nach Mass" (in German).
  4. Johnson, Carl-Johan (August 2021). "DESIGN KNOWLEDGE REUSE IN DESIGN OF PROGRESSIVE STAMPING TOOLS: A QUALITATIVE STUDY" (PDF). International Conference on Engineering Design, Iced21: 1053–1062. Retrieved 1 August 2023.
  5. Thomas Engineering (17 November 2015). "Progressive Metal Stamping".