Stamping A few notes
Stamping presses and stamping dies are tools used to produce high volume sheet
metal parts. These parts achieve their shape through the effects of the die
tooling
Production stamping is generally performed on materials .020” to .080” thick,
but the process also can be applied to foils as thin as .001” or to plate stock
with thickness' approaching 1.000”.
Formability is the primary attribute of sheet metal material. Formability is
further defined as the materials ability to be: bent stretched drawn
Ductility is the
materials ability to deform and elongate without fracture.
The extent to which a stamping is subjected to such deformation is directly related to the part’s overall shape and geometry. Other factors also influence the material’s
formability. They include: the die design the press the press speed lubrication sheet metal feeding mechanisms monitoring and control systems
The word “die” is a generic term used to describe the tooling used to produce
stamped parts. A die set assembly consisting of a male and female component is
the actual tool that produces the shaped stamping. The male and female
components work in opposition to both form and punch holes in the stock. The
upper half of the die set, which may be either the male or female, is mounted on
the press ram and delivers the stroke action. The lower half is attached to an
intermediate bolster plate which in turn is secured to the press bed. Guide pins
are used to insure alignment between the upper and lower halves of the die set.
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.[1] 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 is usually carried out on sheet metal, but can also be used on other materials, such as polystyrene.
Bending is a manufacturing process that produces a V-shape, U-shape, or channel shape along a straight axis in ductile materials, most commonly sheet metal.[1] Commonly used equipment include box and pan brakes, brake presses, and other specialized machine presses
In press brake forming, a work piece is positioned over the die block and the die block presses the sheet to form a shape.[1] Usually bending has to overcome both tensile stresses as well as compressive stresses. When bending is done, the residual stresses cause the material to spring back towards its original position, so the sheet must be over-bent to achieve the proper bend angle. The amount of spring back is dependent on the material, and the type of forming. When sheet metal is bent, it stretches in length. The bend deduction is the amount the sheet metal will stretch when bent as measured from the outside edges of the bend.
Forming is similar to bending. Complex parts such as U-sections, channel sections of different profiles can be produced by doing multiple bends.
There is no change in thickness. Good dimensional repeatability as well as close tolerances is possible with this process.
Blanking and piercing are shearing processes in which a punch and die are used to modify webs. The tooling and processes are the same between the two, only the terminology is different: in blanking the punched out piece is used and called a blank; in piercing the punched out piece is scrapBlanking is cutting up a large sheet of stock into smaller pieces suitable for the next operation in stamping, such as drawing and forming. Often this is combined with piercing.
Piercing is the operation of cutting internal features (holes or slots) in stock. Piercing can also be combined with other operations such as lance and form (to make a small feature such as tab), pierce and extrude (to make an extruded hole). All these operations can be combined with blanking
The most common types of dies perform cutting and forming. Cutting dies are used
to shear sheet material into what is called a blank. These blanks are then
exposed to blanking dies which cut the entire perimeter of the part, or to
forming dies where the blank is stamped into a part. Punching is another
function of cutting dies. Punching is the cutting of a slug from the sheet metal
stock to produce a hole or slot. Cutting dies are also used to trim excess metal
from around a formed part.
Coining is a form of precision stamping in which a workpiece is subjected to a sufficiently high stress to induce plastic flow on the surface of the material. A beneficial feature is that in some metals, the plastic flow reduces surface grain size, and work hardens the surface, while the material deeper in the part retains its toughness and ductility. The term comes from the initial use of the process: manufacturing of coins.
Coining is used to manufacture parts for all industries and is commonly used when high relief or very fine features are required. For example, it is used to produce coins, medals, badges, buttons, precision-energy springs and precision parts with small or polished surface features.
Drawing is a metalworking process which uses tensile forces to stretch metal. It is broken up into two types: sheet metal drawing and wire, bar, and tube drawing. The specific definition for sheet metal drawing is that it involves 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
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.
The feeding system pushes a strip of metal (as it unrolls from a coil) through all of the stations of a progressive stamping die. 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.
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.
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.
The equipments of stamping can be categorized to two types: mechanical presses and hydraulic presses.
Mechanical Presses: Mechanical presses has a mechanical flywheel to store the energy, transfer it to the punch and to the workpiece. They range in size from 20 tons up to 6000 tons. Strokes range from 5 to 500 mm (0.2 to 20 in) and speeds from 20 to 1500 strokes per minute. Mechanical presses are well suited for high-speed blanking, shallow drawing and for making precision parts
The equipments of stamping can be categorized to two types: mechanical presses and hydraulic presses.
Hydraulic Presses: Hydraulic Presses use hydraulics to deliver a controlled force. Tonnage can vary from 20 tons to a 10,000 tons. Strokes can vary from 10 mm to 800 mm (0.4 to 32 in). Hydraulic presses can deliver the full power at any point in the stroke; variable tonnage with overload protection; and adjustable stroke and speed. Hydraulic presses are suitable for deep-drawing, compound die action as in blanking with forming or coining, low speed high tonnage blanking, and force type of forming rather than displacement type of forming.
metal parts. These parts achieve their shape through the effects of the die
tooling
Production stamping is generally performed on materials .020” to .080” thick,
but the process also can be applied to foils as thin as .001” or to plate stock
with thickness' approaching 1.000”.
Formability is the primary attribute of sheet metal material. Formability is
further defined as the materials ability to be: bent stretched drawn
Ductility is the
materials ability to deform and elongate without fracture.
The extent to which a stamping is subjected to such deformation is directly related to the part’s overall shape and geometry. Other factors also influence the material’s
formability. They include: the die design the press the press speed lubrication sheet metal feeding mechanisms monitoring and control systems
The word “die” is a generic term used to describe the tooling used to produce
stamped parts. A die set assembly consisting of a male and female component is
the actual tool that produces the shaped stamping. The male and female
components work in opposition to both form and punch holes in the stock. The
upper half of the die set, which may be either the male or female, is mounted on
the press ram and delivers the stroke action. The lower half is attached to an
intermediate bolster plate which in turn is secured to the press bed. Guide pins
are used to insure alignment between the upper and lower halves of the die set.
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.[1] 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 is usually carried out on sheet metal, but can also be used on other materials, such as polystyrene.
Bending is a manufacturing process that produces a V-shape, U-shape, or channel shape along a straight axis in ductile materials, most commonly sheet metal.[1] Commonly used equipment include box and pan brakes, brake presses, and other specialized machine presses
In press brake forming, a work piece is positioned over the die block and the die block presses the sheet to form a shape.[1] Usually bending has to overcome both tensile stresses as well as compressive stresses. When bending is done, the residual stresses cause the material to spring back towards its original position, so the sheet must be over-bent to achieve the proper bend angle. The amount of spring back is dependent on the material, and the type of forming. When sheet metal is bent, it stretches in length. The bend deduction is the amount the sheet metal will stretch when bent as measured from the outside edges of the bend.
Forming is similar to bending. Complex parts such as U-sections, channel sections of different profiles can be produced by doing multiple bends.
There is no change in thickness. Good dimensional repeatability as well as close tolerances is possible with this process.
Blanking and piercing are shearing processes in which a punch and die are used to modify webs. The tooling and processes are the same between the two, only the terminology is different: in blanking the punched out piece is used and called a blank; in piercing the punched out piece is scrapBlanking is cutting up a large sheet of stock into smaller pieces suitable for the next operation in stamping, such as drawing and forming. Often this is combined with piercing.
Piercing is the operation of cutting internal features (holes or slots) in stock. Piercing can also be combined with other operations such as lance and form (to make a small feature such as tab), pierce and extrude (to make an extruded hole). All these operations can be combined with blanking
The most common types of dies perform cutting and forming. Cutting dies are used
to shear sheet material into what is called a blank. These blanks are then
exposed to blanking dies which cut the entire perimeter of the part, or to
forming dies where the blank is stamped into a part. Punching is another
function of cutting dies. Punching is the cutting of a slug from the sheet metal
stock to produce a hole or slot. Cutting dies are also used to trim excess metal
from around a formed part.
Coining is a form of precision stamping in which a workpiece is subjected to a sufficiently high stress to induce plastic flow on the surface of the material. A beneficial feature is that in some metals, the plastic flow reduces surface grain size, and work hardens the surface, while the material deeper in the part retains its toughness and ductility. The term comes from the initial use of the process: manufacturing of coins.
Coining is used to manufacture parts for all industries and is commonly used when high relief or very fine features are required. For example, it is used to produce coins, medals, badges, buttons, precision-energy springs and precision parts with small or polished surface features.
Drawing is a metalworking process which uses tensile forces to stretch metal. It is broken up into two types: sheet metal drawing and wire, bar, and tube drawing. The specific definition for sheet metal drawing is that it involves 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
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.
The feeding system pushes a strip of metal (as it unrolls from a coil) through all of the stations of a progressive stamping die. 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.
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.
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.
The equipments of stamping can be categorized to two types: mechanical presses and hydraulic presses.
Mechanical Presses: Mechanical presses has a mechanical flywheel to store the energy, transfer it to the punch and to the workpiece. They range in size from 20 tons up to 6000 tons. Strokes range from 5 to 500 mm (0.2 to 20 in) and speeds from 20 to 1500 strokes per minute. Mechanical presses are well suited for high-speed blanking, shallow drawing and for making precision parts
The equipments of stamping can be categorized to two types: mechanical presses and hydraulic presses.
Hydraulic Presses: Hydraulic Presses use hydraulics to deliver a controlled force. Tonnage can vary from 20 tons to a 10,000 tons. Strokes can vary from 10 mm to 800 mm (0.4 to 32 in). Hydraulic presses can deliver the full power at any point in the stroke; variable tonnage with overload protection; and adjustable stroke and speed. Hydraulic presses are suitable for deep-drawing, compound die action as in blanking with forming or coining, low speed high tonnage blanking, and force type of forming rather than displacement type of forming.
