Article Description : This article titled ‘Metal Forming Suppliers- Global Sourcing considerations’ explains the process and its types that a professional must know before he/ she decides to involve in supplier sourcing. crystallization
The process of complete physical reshaping of a work-metal without any alteration in its mass is known as Metal Forming. In this process, a certain amount of force is applied on the work-metal to change it to a desired shape. Unlike elastic deformation, this process allows the change in shape to remain in the metal even after the stress is removed
It is classified into two types :
1. Bulk Metal forming
2. Sheet Metal forming
1. Bulk Metal Forming :
In this process, the metal shape deformed has a relatively low surface area. This process changes the shape of the work-metal massively and is mostly done in hot working conditions with temperatures above the re-crystallization point.
Bulk Metal forming is classified into the following types :
a. Rolling :
This process uses rolls to deform a work-metal. It reduces the metal thickness by passing the work-metal through two rollers. The roll formed metal is then compressed by heat treatment.
Types : Sheet rolling, Shape rolling, Tube reducing, Flow turning, Ring rolling, Gear rolling, Cross rolling, Roll forging, Surface rolling, Rotary tube piercing, Roll Bending, Flat rolling, Controlled forging, Structural shape rolling, etc.
b. Forging :
It is a process in which compressing forces of dies are used to reshape a metal. The metal finally acquires the shape imparted by the dies.
Types : Closed die-forging with flash, Closed die-forging without flash, Coining, Upsetting, Impression die-forging, Seamless rolled ring forging, Electro-upsetting, Radial forging, Backward extrusion forging, Hobbing, Isothermal forging, Nosing, Open-die forging, Orbital forging, etc.
c. Extrusion :
In this method, the work-metal is passed through a die that contains an opening. As the metal is pushed along the opening, the metal undergoes compression and comes out through a die- hole. This results in a constant cross-sectional metal piece after the process.
Types : Direct extrusion, Indirect extrusion, Tube extrusion, Impact extrusion, Hydraulic extrusion, Lubricated direct hot extrusion, Hydro-static extrusion, non-lubricated hot extrusion, etc.
d. Drawing :
This process is similar to extrusion forming in the aspect of reshaping metal using die-opening. Except the fact that the work-metal is pulled along the die-hole instead of being pushed across the die opening.
Types : Sheet metal drawing, Deep drawn stamping, etc. Deep drawn stamping can further be classified into the following processes : Beading, Coining, Curling, Extruding, Ironing, Marking, Necking, Notching, Stamping, Threading, Trimming, etc.
2. Sheet Metal forming :
In this process, the metal shape deformed has a relatively large surface area. This process usually involves metals in the form of sheets, coils or strips. Apart from dies, this process uses punching tools for deforming the metal-shape.
Sheet metal forming process is of 3 types :
b. Deep drawing
a. Bending :
It is a process in which a punch tool is used to compress the metal to impart a Bend shape.
b. Deep drawing :
This type of forming is characterized by reformation of metals in the form of cups. A flat sheet of metal is pushed through a die-hole with a holder support, and a punch compresses the work-metal to deform the metal into a cup-shaped material. The loads and stresses placed on the metal causes the end product to be stable and strong.
c. Shearing :
It is a metal-cutting process that uses shear stress caused by dies without formation of chips and undergoing plastic deformation. This process is considered as the core producer of the manufacturing sector. Every industry requires formed machine parts with respect to its applications. The increase in the demand for instant machine parts has raised the need for technological advancements in the manufacturing industry. The manufacturing processes are therefore expected to adapt to automation in the coming years to cope up with the increasing demand of quality.
The yield strength of a metal determines the extent to which a metal can bear stress. Metal forming process requires application of pressure that exceeds the work-piece’s yield strength. Usually metals undergo 2 types of deformation on application of pressure.
1 Elastic Deformation :
On application of pressure, a metal’s shape changes and then gets back to its original geometry. This is known as Elastic Deformation.
2 Plastic Deformation :
When pressure is applied on a metal, the shape of the work-piece changes and do not get back to its original geometry. This is known as Plastic Deformation.
Flow Stress : It is the amount of stress that has to applied at each point of the process. This parameter can be used to determine the exact change occurring at any particular point in the process. This value is necessary to determine the maximum stress that can be applied on the metal in order to be cautious of breaking.
Strain rate : The rate or pace at which the deformation of a metal occurs in a metal forming process is known as strain rate. The strain rate value depends on the type of forming process involved. The metal characteristics and also the working temperatures also an adverse effect on the strain rate value.
During any industrial operations, it is essential to know the performance characteristics of metals at different temperatures. As temperature is one of the most influential factors in terms of manufacturing, it is very necessary to study each metal’s temperature characteristics before processing them.
On studying different metals with respect to metal forming, the working process is classified as follows :
Cold working :
The Cold forming process or the cold working process refers to operations that are carried out at room temperatures or at very high temperatures. During this process, metals exhibit less ductility making the strain value higher than other operations. Since the value at which the metal can be strained or deformed is high, a greater stress is required for successful deformation. In addition to higher force requirements, it is also necessary to be cautious about metal fractures.
This is due to the rigid state of metals at room temperature. One can alter the physical nature of the metal flexible to deform only by heating. this is because metals exhibit higher ductility when heated. The bonds between their physical atoms are weaker and are compatible for any structural changes through stress/ strain.
Warm working :
Warm working refers to temperatures a little above cold working. This is because warm working process does not require greater stress or forces as required in cold working process.
Hot working :
This forming process involves temperatures above fractional crystallization temperature. Though the temperature increase is necessary for easy deformation, Hot working has to be carried out with utmost cautiousness. There are several defects that are possible to arise during hot working process. But the best part of a hot working process is the ability to change shapes massively through increased ductility. This process also closes up pores in the internal structure due to the flow of metal across the entire workpiece. This process is very applicable for complex shapes.
The Metal forming industry is researching in areas that manufactures products beyond the existing conventional methods. The Metalworking industry look for such innovations in the Metal forming sector. The small-scale sectors are also expected to widen their capabilities with the increase in awareness among the products among consumers.
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