A modern variation of the spinning spinning process is known as shearforming (also called flow forming or floturning). This is a sophisticated version of the ancient art of metal spinning. It has the added ability of coping with appreciable variations in wall thickness; and close tolerances are easily obtainable by the operator through the machine controller.
In metal spinning, a flat or almost flat blank of sheet metal is forced by an operator, learning on a long-handled forming tool, to conform to a convex mandrel. In the process, the wall thickness of the spun part is reasonably constant, except for some streching which occurs where the blank is bent. This thickness change is not sought after -in fact, it is normally undesired- but it is accepted as an inconvenience of the process.
Shearforming, on the other hand, allows the creation of thickness which vary from point to point by as much as 100%. Another constraint of spinning involves blank thickness and radii. In spinning, blank thickness is generally less than 1/8'', and most workpiece radii are more than 5 times blank thickness. Normally, shearforming machines can handle blanks much thicker, and can bend any radius the material itself can endure. Of course, this depends somewhat on machine size. However, both processes can, under the proper circumstances, form steel plate 1'' thick.
(Brown J. A., Modern manufacturing processes, 1991, p. 117,118)
Shearforming (new) [manufacturing method]
In this process, a flat sheet is formed over a mandrel by means of a shear forming roll that is reducing its thickness but keeping its diameter constant. This process should not be mixed with sheet forming process spinning in which the sheet thickness is more or less constant but the diameter of initial workpiece is reduced.
If the final thickness is selscted correctly the plastic deformation is confined only at the roll region, so that the rest of the workpiece remains stress-free.
(Springer Handbook of Mechanical Engineering, Author: Karl-Heinrich Grote,Erik K. Antonsson p.585)
-new definition is more clear
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Electroforming: (10.50 - 24.03.2011)(old)
A variation of electroplating, electroforming actually is a metal-fabricating process. Metal is electrodeposited on a mandrel (also called a mold or a matrix), which is then removed; thus, the coating itself becomes the product. Both simple and cmplex shapes can be produced by electroforming, with wall thicknesses as small as 0.0025 mm. Parts may weigh from a few grams to as much as 270 kg. Production rates can be increased through the use of multiple mandrels.
Mandrels are made from a variety of materials: metallic (zinc or aluminum) or nonmetallic (which can be made electrically conductive with the proper coatings). Mandrels should be able to be removed physically without damaging the electroformed part. They also may be made of low-melting alloys, wax, or plastics, all of which can be melted away or dissolved with suitable chemicals.
The electroforming process is particularly suitable for low production quantities or intricate parts (such as molds, dies, waveguides, nozzles and bellows) made of nickel, copper, gold, and silver. The process is also suitable for aerospace, electronics, and electro-optics applications.
A variation of electroplating, electroforming actually is a metal-fabricating process. Metal is electrodeposited on a mandrel (also called a mold or a matrix), which is then removed; thus, the coating itself becomes the product. Both simple and cmplex shapes can be produced by electroforming, with wall thicknesses as small as 0.0025 mm. Parts may weigh from a few grams to as much as 270 kg. Production rates can be increased through the use of multiple mandrels.
Mandrels are made from a variety of materials: metallic (zinc or aluminum) or nonmetallic (which can be made electrically conductive with the proper coatings). Mandrels should be able to be removed physically without damaging the electroformed part. They also may be made of low-melting alloys, wax, or plastics, all of which can be melted away or dissolved with suitable chemicals.
The electroforming process is particularly suitable for low production quantities or intricate parts (such as molds, dies, waveguides, nozzles and bellows) made of nickel, copper, gold, and silver. The process is also suitable for aerospace, electronics, and electro-optics applications.
(Kalpakjian S. Schmid S.R.,Manufacturing Engineering and Technology Sixth Edition in SI Units, p. 986)
Electroforming(new) [manufacturing]
Electroforming is the process of synthesizing a metal object by controlling the ectrodeposition of metal via an electrolytic solution. A metal layer is built up on a metal surface or on any surface that has been rendered electroconductive through the application of a paint containing metal particles. The master pattern is placed in electrical contact with the cathode, and the target material for fabrication is placed in contact with the anode. he material at the anode is oxidized and dissolved. the cations are reduced at the cathode and the metal is deposited on the master. The thickness of the electro-formed nickel layer can be controlled by the current density and the deposition time.
(Micro / Nano Replication: Processes and Applications Author: Shinill Kang p.50)
-new definition is better and more understandable
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Magneforming (24 Mart 2011 12:45)(old)
Magneforming is also called electromagnetic forming(EMF) is an assembly technique that is widely used to both join and shape metals and other materials with precision and rapidity, and without the heat effects and tool marks associated with other techniques. Also known as magnetic pulse forming, the EMF process uses the direct application of a pressure created in an intense, transient magnetic field. Without mechanical contact, a metal workpiece is formed by the passage of a pulse of electric current through a forming coil.
The parameters that determine the applicability of the EMF process are:
· Forming can be accomplished through a nonmetallic coating or container because the magnetic field passes through electrical nonconductors
· Most of the forming takes place after the pressure impulse has ended, in contrast to most metal-forming processes. The metal is rapidly accelerated, gaining a large amount of kinetic energy by moving only a short distance during the impulse. This kinetic energy subsequently does the actual work of forming
· The metals that are most efficiently formed by EMF are those with relatively high electrical conductivity, such as copper, aluminum, low-carbon steel, brass, and molybdenum. Metals with lower conductivity, such as stainless steel, can be formed by using either very high energy or an intermediate, highly conductive "driver" · The ratio of the masses of pieces used in assembly operations may be much more significant than their relative mechanical strength or elastic properties. Because EMF does not use static forces, relatively light structures can be used to support the dies
· No torque is applied to the workpiece in swaging and expanding operations, in contrast to spinning and rolling. Because the magnetic field behaves much like a compressed gas, it exerts a uniform pressure that is relatively independent of variations in spacing between the workpiece and the forming coil
· No lubricant is required because the contact between the magnetic field and the workpiece is frictionless
· The peak pressure is limited (by the strength of the forming-coil material) to much lower values than are commonly encountered in shearing, punching, and upsetting operations. However, the pressure that can be applied by the magnetic pulse can be very high compared to the average pressure in mechanical forming
· The process, being purely electromagnetic, is not limited to repetition rate by the mechanical inertia of moving parts. The timing of the magnetic impulse can be synchronized with microsecond precision, and machines can be made to function at repetition rates of hundreds of operations per minute. The strength of the magnetic impulse can be controlled electrically with high precision The major application of EMF is the single-step assembly of metal parts to each other or to other components, although it is also used to shape metal parts. Within the transportation industry, for example, one automotive producer assembles aluminum driveshafts without welding to save a significant amount of weight in light trucks and vans to meet requirements for reduced energy consumption. Using the EMF process allows the joining of an impact-extruded aluminum yoke to a seamless tube without creating the heat-affected zone associated with welding.
(Forming and Forging,ASM Handbook Volume 14, Joseph R. Davis; Page:1420,1421)
Magneforming is also called electromagnetic forming(EMF) is an assembly technique that is widely used to both join and shape metals and other materials with precision and rapidity, and without the heat effects and tool marks associated with other techniques. Also known as magnetic pulse forming, the EMF process uses the direct application of a pressure created in an intense, transient magnetic field. Without mechanical contact, a metal workpiece is formed by the passage of a pulse of electric current through a forming coil.
The parameters that determine the applicability of the EMF process are:
· Forming can be accomplished through a nonmetallic coating or container because the magnetic field passes through electrical nonconductors
· Most of the forming takes place after the pressure impulse has ended, in contrast to most metal-forming processes. The metal is rapidly accelerated, gaining a large amount of kinetic energy by moving only a short distance during the impulse. This kinetic energy subsequently does the actual work of forming
· The metals that are most efficiently formed by EMF are those with relatively high electrical conductivity, such as copper, aluminum, low-carbon steel, brass, and molybdenum. Metals with lower conductivity, such as stainless steel, can be formed by using either very high energy or an intermediate, highly conductive "driver" · The ratio of the masses of pieces used in assembly operations may be much more significant than their relative mechanical strength or elastic properties. Because EMF does not use static forces, relatively light structures can be used to support the dies
· No torque is applied to the workpiece in swaging and expanding operations, in contrast to spinning and rolling. Because the magnetic field behaves much like a compressed gas, it exerts a uniform pressure that is relatively independent of variations in spacing between the workpiece and the forming coil
· No lubricant is required because the contact between the magnetic field and the workpiece is frictionless
· The peak pressure is limited (by the strength of the forming-coil material) to much lower values than are commonly encountered in shearing, punching, and upsetting operations. However, the pressure that can be applied by the magnetic pulse can be very high compared to the average pressure in mechanical forming
· The process, being purely electromagnetic, is not limited to repetition rate by the mechanical inertia of moving parts. The timing of the magnetic impulse can be synchronized with microsecond precision, and machines can be made to function at repetition rates of hundreds of operations per minute. The strength of the magnetic impulse can be controlled electrically with high precision The major application of EMF is the single-step assembly of metal parts to each other or to other components, although it is also used to shape metal parts. Within the transportation industry, for example, one automotive producer assembles aluminum driveshafts without welding to save a significant amount of weight in light trucks and vans to meet requirements for reduced energy consumption. Using the EMF process allows the joining of an impact-extruded aluminum yoke to a seamless tube without creating the heat-affected zone associated with welding.
(Forming and Forging,ASM Handbook Volume 14, Joseph R. Davis; Page:1420,1421)
Magneforming(new) [manufacturing]
Magneforming is when an electric current generates a pulsed magnetic field close to a metal conductuor so that a controllable force is created which can be used to shape metal without actual contact.
The basic components of magneform machine are; energy store capacitors, a work coil and switching devices. High voltage capacitors are charged, then discharged through a coil, inducing an intense magnetic field. This field, in turn, induces current in the conducting workpiece setting up an opposing magnetic field; the net magnetic force does the forming.
(Modern manufacturing processes Author: James A. Brown p.87-88)
-new definition is more summarized and understandable
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