Die (manufacturing)

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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, [1] as opposed to drawing dies (used in the manufacture of wire) and casting dies (used in molding) which are not. Like molds, dies are generally customized to the item they are used to create.

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Products made with dies range from simple paper clips to complex pieces used in advanced technology. Continuous-feed laser cutting may displace the analogous die-based process in the automotive industry, [2] among others.

Die stamping

Progressive die with scrap strip and stampings ProgressiveDieToyota-strip-scrap.jpg
Progressive die with scrap strip and stampings

Blanking and piercing are two die cutting operations, and bending is an example of a die forming operation.

Die forming

Forming operations work by deforming materials like sheet metal or plastic using force (compression, tension, or both) and rely on the material's mechanical properties. [3] Forming dies are typically made by tool and die makers and put into production after mounting into a press.

Differences between materials

For the vacuum forming of plastic sheet only a single form is used, typically to form transparent plastic containers (called blister packs) for merchandise. Vacuum forming is considered a simple molding thermoforming process but uses the same principles as die forming.

For the forming of sheet metal, such as automobile body parts, two parts may be used: one, called the punch, performs the stretching, bending, and/or blanking operation, while another part that is called the die block securely clamps the workpiece and provides similar stretching, bending, and/or blanking operation. The workpiece may pass through several stages using different tools or operations to obtain the final form. In the case of an automotive component, there will usually be a shearing operation after the main forming is done. Additional crimping or rolling operations may be performed to ensure that all sharp edges are hidden and/or to add rigidity to the panel.

Die components

The main components of a die set (including press mounting) are as follows. Note that because nomenclature varies between sources, alternate names are in parenthesis:

Process

  1. Accuracy. A properly sharpened die, with the correct amount of clearance between the punch and die, will produce a part that holds close dimensional tolerances in relationship to the part's edges.
  2. Appearance. Since the part is blanked in one operation, the finish edges of the part produces a uniform appearance as opposed to varying degrees of burnishing from multiple operations.
  3. Flatness. Due to the even compression of the blanking process, the end result is a flat part that may retain a specific level of flatness for additional manufacturing operations.
  1. Bulging fluid dies: Uses water or oil as a vehicle to expand the part.
  2. Bulging rubber dies: Uses a rubber pad or block under pressure to move the wall of a workpiece.
Roll Forming Stand Zg-prof.jpg
Roll Forming Stand

Steel-rule die

Steel-rule die, also known as cookie cutter dies, are used for cutting sheet metal and softer materials, such as plastics, wood, cork, felt, fabrics, and paperboard. The cutting surface of the die is the edge of hardened steel strips, known as steel rule. These steel rules are usually located using saw or laser-cut grooves in plywood. The mating die can be a flat piece of hardwood or steel, a male shape that matches the workpiece profile, or it can have a matching groove that allows the rule to nest into. Rubber strips are wedged in with the steel rule to act as the stripper plate; the rubber compresses on the down-stroke and on the up-stroke it pushes the workpiece out of the die. The main advantage of steel-rule dies is the low cost to make them, as compared to solid dies; however, they are not as robust as solid dies, so they are usually only used for short production runs. [9]

Rotary die

In the broadest sense, a rotary die is a cylindrical shaped die that may be used in any manufacturing field. However, it most commonly refers to cylindrical shaped dies used to process soft materials, such as paper or cardboard. Two rules are used, cutting and creasing rules. This is for corrugated boards whose thickness is more than 2 mm. Rotary dies are faster than flat dies. [10] [11]

The term also refers to dies used in the roll forming process. [12]

Wire pulling

Wire-making dies have a hole through the middle of them. A wire or rod of steel, copper, other metals, or alloy enters into one side and is lubricated and reduced in size. The leading tip of the wire is usually pointed in the process. The tip of the wire is then guided into the die and rolled onto a block on the opposite side. The block provides the power to pull the wire through the die.

The die is divided into several different sections. First is an entrance angle that guides the wire into the die. Next is the approach angle, which brings the wire to the nib, which facilitates the reduction. Next is the bearing and the back relief. Lubrication is added at the entrance angle. The lube can be in powdered soap form. If the lubricant is soap, the friction of the drawing of wire heats the soap to liquid form and coats the wire. The wire should never actually come in contact with the die. A thin coat of lubricant should prevent the metal to metal contact.

For pulling a substantial rod down to a fine wire a series of several dies is used to obtain progressive reduction of diameter in stages.

Standard wire gauges used to refer to the number of dies through which the wire had been pulled. Thus, a higher-numbered wire gauge meant a thinner wire. Typical telephone wires were 22-gauge, while main power cables might be 3- or 4-gauge.

Related Research Articles

Electrical discharge machining Metal fabrication process whereby a desired shape is obtained by using electrical discharges to remove material

Electrical discharge machining (EDM), also known as spark machining, spark eroding, die sinking, wire burning or wire erosion, is a metal fabrication process whereby a desired shape is obtained by using electrical discharges (sparks). Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of the electrodes is called the tool-electrode, or simply the tool or electrode, while the other is called the workpiece-electrode, or work piece. The process depends upon the tool and work piece not making physical contact.

Forging 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. Since the Industrial Revolution, forged parts are widely used in mechanisms and machines wherever a component requires high strength; such forgings usually require further processing to achieve an almost finished part. Today, forging is a major worldwide industry.

Metalworking Process of making items from metal

Metalworking is the process of shaping and reshaping metals 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.

Metal fabrication

Metal fabrication is the creation of metal structures by cutting, bending and assembling processes. It is a value-added process involving the creation of machines, parts, and structures from various raw materials.

Plasma cutting

Plasma cutting is a process that cuts through electrically conductive materials by means of an accelerated jet of hot plasma. Typical materials cut with a plasma torch include steel, stainless steel, aluminum, brass and copper, although other conductive metals may be cut as well. Plasma cutting is often used in fabrication shops, automotive repair and restoration, industrial construction, and salvage and scrapping operations. Due to the high speed and precision cuts combined with low cost, plasma cutting sees widespread use from large-scale industrial CNC applications down to small hobbyist shops.

Sheet metal

Sheet metal is metal formed by an industrial process into thin, flat pieces. Sheet metal is one of the fundamental forms used in metalworking, and it can be cut and bent into a variety of shapes. Countless everyday objects are fabricated from sheet metal. Thicknesses can vary significantly; extremely thin sheets are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate steel or "structural steel".

Hydroforming Method of shaping metal through pressurized water

Hydroforming is a cost-effective way 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 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.

Punch press

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.

Drawing (manufacturing) Metalworking process

Drawing is a metalworking process that uses tensile forces to stretch (elongate) metal, glass, or plastic. As the metal is drawn (pulled), it stretches to become thinner, to achieve a desired shape and thickness. Drawing is classified into two types: sheet metal drawing and wire, bar, and tube drawing. Sheet metal drawing is defined as plastic deformation over a curved axis. For wire, bar, and tube drawing, the starting stock is drawn through a die to reduce its diameter and increase its length. Drawing is usually performed at room temperature, thus classified a cold working process, however, drawing may also be performed at elevated temperatures to hot work large wires, rods or hollow sections in order to reduce forces.

Punching

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.

Progressive stamping Metalworking method

Progressive stamping 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.

Die cutting (web)

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.

Stamping (metalworking) 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. 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 unwinding of 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.

Deep drawing

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. The flange region experiences a radial drawing stress and a tangential compressive stress due to the material retention property. These compressive stresses result in flange wrinkles. Wrinkles can be prevented by using a blank holder, the function of which is to facilitate controlled material flow into the die radius.

Photochemical machining Process that uses chemicals to machine sheet metal

Photochemical machining (PCM), also known as photochemical milling or photo etching, is a chemical milling process used to fabricate sheet metal components using a photoresist and etchants to corrosively machine away selected areas. This process emerged in the 1960s as an offshoot of the printed circuit board industry. Photo etching can produce highly complex parts with very fine detail accurately and economically.

Shearing, also known as die cutting, is a process which cuts stock without the formation of chips or the use of burning or melting. Strictly speaking, if the cutting blades are straight the process is called shearing; if the cutting blades are curved then they are shearing-type operations. The most commonly sheared materials are in the form of sheet metal or plates, however rods can also be sheared. Shearing-type operations include: blanking, piercing, roll slitting, and trimming. It is used for metal, fabric, paper and plastics.

Blanking and piercing

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.

There are many types of shears used to shear sheet metal.

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. 1 2 Hedrick, Art (July 18, 2018). "Die Basics 101: Intro to Stamping". The Fabricator. FMA Communications, Inc., 2135 Point Blvd., Elgin, IL 60123. Retrieved January 25, 2021.
  2. Finn, Jay (March 19, 2020). "The case for laser blanking in automotive stamping". Stamping Journal. FMA Communications, Inc. Retrieved January 25, 2021.
  3. Hedrick, Art (July 18, 2018). "Die Basics 101: Forming operations". The Fabricator. Retrieved January 25, 2021.
  4. 1 2 Hedrick, Art (July 18, 2018). "Die basics 101: Common stamping die components (Part 1 of 2)". The Fabricator. Retrieved January 25, 2021.
  5. Delfini, Ron (January 17, 2020). "Parts of a Die". ESI Blog. Engineering Specialties, Inc., 452 Twin Lakes Rd., North Branford, CT. Retrieved January 25, 2021.
  6. Misumi Corporation (February 12, 2010). "Press Dies Tutorial § 028, Basics of Die Structure (3)". Misumi Technical Tutorial. Retrieved January 25, 2021.
  7. Hedrick, Art (July 18, 2018). "Die basics 101: Common stamping die components (Part 2 of 2)". The Fabricator. Retrieved January 25, 2021.
  8. Misumi Corporation, Inc. (July 13, 2012). "Press Dies Tutorial §130, Design of Blanking Dies". Misumi Technical Tutorial. Retrieved January 25, 2021.
  9. Degarmo, Black & Kohser 2003 , pp. 430–431.
  10. Twede, Diana; Selke, Susan E. M. (2005), Cartons, crates and corrugated board: handbook of paper and wood packaging technology, DEStech, p. 436, ISBN   978-1-932078-42-8, archived from the original on 2017-11-28.
  11. Soroka, Walter (2008), Illustrated Glossary of Packaging Terminology (2nd ed.), DEStech, p. 64, ISBN   978-1-930268-27-2, archived from the original on 2017-11-28.
  12. Halmos, George T. (2006), Roll forming handbook, CRC Press, p. 4‑46, ISBN   978-0-8247-9563-4, archived from the original on 2017-11-28.

Bibliography

Further reading