Forging Industries

 Introduction

                                 Forging is a manufacturing process involving the shaping of a metal through hammering, pressing, or rolling. These compressive forces are delivered with a hammer or die. Forging is often categorized according to the temperature at which it is performed - cold, warm, or hot forging. A wide range of metals can be forged. Since the industrial revolution, forged parts are widely used in mechanism and machines wherever a component requires high strength, such forging usually require further processing such machining to achieve a finished parts. Today, forging is a major worldwide industry. 

                           In modern times, industrial forging is done either with presses or with hammers powered by compressed air, electricity, hydraulics or steam. These hammers may have reciprocating weights in the thousands of pounds. Forging can produce a piece that is stronger than an equivalent cast or machined parts. As the metal is shaped during the forging process, its internal grain texture deforms to follow the general shape of the parts. As a result, the texture variation is continuous throughout the part, giving rise to a piece with improved strength characteristics. Additionally, forgings can achieve a lower total cost than casting or fabrication. 

Types Of Forgings

                              The types of forgings can be divided as per process of forgings and variety of metal parts. Some important types of forgings are as follows. 

1) Cold Forging

                           The cold forging process is designed to create parts and components that display enhanced surface finish quality and tight tolerance dimensions. Unlike most other forging processes, cold forging does not utilize heat for part structure shaping but rather colder temperatures to produce various parts. Cold forging is used to produce various parts and components, including shafts, hollow parts with shafts and stems, odd configuration and cup shaped geometries. 

                           Cold forging creates tight tolerances, produces good surface finish quality. In cold forging little to no material waste, increased yield and tensile strength. 

2) Open Die Forging

                               Open die forging is performed between flat dies with no precut profiles is the dies. Open die forging, also known as free forging or smith forging, is the process of striking a hammer to deform a piece of metal, typically placed on  a stationary anvil. This type of forging techniques is generally used to shape metal parts, steels and alloy steels. The parts produced is not of greater accuracy and hence require machining operations on the lathes ( Turning), milling machines, CNC & VMC, etc. to give it the desired accuracy. 

                         The main parts of open die forgings are Hammer or Ram, Die, Anvil and Workpiece. 

3) Drop Forging 

                           Drop Forging is a that uses a pair of impression dies and a heavy hammer to form and compress metal bars or billets into complex shapes. The die cavity is the desired shape of the final forging. The equipment used in the drop forging process is known as a power or drop hammer. This type of forging is used when a large quantity of certain components with sound and good quality forgings are to be produced. 

                           The products obtained in drop forgings are connecting rod, crank, crank shaft, crane hook, spanner, high tensile fasteners, gears, etc. Drop forging process is widely used in automobile industries, airplane parts industries, rail road equipment industries, engine manufacturing industries, etc. 

4) Closed Die Forging

                           Closed die forging is a forging process in which dies moves towards each other and covers the workpiece in whole or in part. The heated raw material, which is approximately the shape or size of the final forged part, is placed in the bottom die. The shape of the forging is incorporated in the top or bottom die as a negative image. Coming from above, the impact of the top die on the raw material forms it into the required forged form. 

                               Closed die forging is mainly used for the production of steel and aluminium components. So the application of closed die forging is wide. It could be used for the production of mining drill bits, forestry wear part, agriculture wear part, construction wear part, rigging and lifting components, etc. 

5) Hot Forging

                            Hot forging can be defined as "a metal shaping process in which a malleable metal parts, known as a billet or workpiece, is worked to a predetermined shape by one or more processes such as hammering, upsetting, pressing and so forth where the workpiece is heated upto about 75% of its melting temperature."

                             Hot forging is a process that can be used to produce a wide variety of parts used in a lot of sectors such as aerospace ( aircraft engines, airframe and auxiliary equipment), automotive (joints, chassis parts, crank shafts), electricity (power generation, transmission), machinery and equipment, hand and industrial tools, construction, mining, plumbing ( pipeline fittings, valves, flanges), ship building, railroad equipment, etc. 

6) Impression die forging

                              Impression die forging is a metal deformation techniques in which a billet is compressed between two sets of die to form a complex parts. "Impression" refers to the pre-cut profile of the dies used during the forging process, which are customized based on the part that is being produced. Depending on the components design, impression die forging may require one set of dies or a multi - stage process with many sets of dies. 

                               The examples of impression die forging is the, two dies are brought together and the workpiece undergoes plastic deformation until its enlarged sides touch the side walls of the die. Then a small amount of material begins to flow outside the die impression forming flash that is gradually thinned. 

7) Roll Forging

                             Roll forging, also known as roll forming. It is a forging method that uses opposing rolls to form a metal parts. Roll forging consists of two cylindrical or semi - cylindrical horizontal rolls that deform a round or flat bar stock. this work to reduce its thickness and increase its length. It is a process for simultaneously reducing the cross - sectional area and changing the shape of heated bars, billets, ingots or plates. The precisely shaped geometry of grooves on the roll, forge the part to the required dimensions. The forging geometry of the rolls used to forge metal parts is only present over a portion of the roll's circumstances. The roll forming eliminates multiple stage operations such as trim scrap, slitting, burrs, notching and punching. 

8) Isothermal Forging

                            Isothermal forging technology refers to a closed - die process. The workpiece and dies get heated at the exact temperature to ensure that engineering parts formation happens without any temperature in these workpiece. The name comes from "iso" which means "equal." This forging method is commonly used for forging aluminium, which has a lower forging temperature than other metals such as steel. Isothermal forging has a significant cost advantages, particularly in precision metal manufacturing in high volume production runs. The material used in forgings are less expensive when compared with other materials used in metal working processes. Furthermore, it requires fewer secondary operations and very low cost. 

9) Induction Forging

                                 Induction forging refers to the use of an induction heater to pre-heat metal prior to deformation using a process or hammer. Induction heating is a non contact process which use the principle of electromagnetic induction to produce heat in a workpiece. Electric current can flow through a material when it is placed in a strong alternative magnetic field, this cause Joule heating. With magnetic materials, the excess heat is generated below the Curie Point, " the Curie Point is the temperature at which certain magnetic materials undergo a sharp change in their magnetic properties. Induction forging makes it possible to control the temperature and position of the area to be heated very accurately and thus leads to a high final quality and repeatability. Induction forging is energy efficient as the heat is internally generated within the components, therefore production costs are reduced. The major products are induction forging is small fasteners used in the aerospace sectors, crank shafts, propeller shafts and fasteners used in rail engines. 

10) Multidirectional Forging

                                Multidirectional forging is forming of a work piece in a single step in several directions. The multidirectional forming takes place through constructive measures of the tool. The vertical movement of the press ram is redirected using wedges which distributes and redirects the force of the forging press in horizontal directions. In short, in multidirectional forging, each sample is initially forged in one direction and then it is rotated by 90 degree and forged in that direction, this constitutes a pass. Alternate forging of these alloys takes place in order to achieve bulk grain refinement.

Applications Of Forgings

1) Automobile Industries

2) Railways Industries

3) Defense Sectors

4) Valves And Fittings

5) Machinery And Equipment

6) Hand Tools And Hardware

7) Aerospace 

8) High Tensile Fasteners And Precision Parts Manufacturing Industries

Advantages Of Forging Process

                                 The primary advantages of forging over machining is that it can produce stronger parts with more excellent impact resistance than those achieved through machining operations. The process also allows for better grain flow throughout the region since it is worked from the inside out. This helps reduce defects and improve product quality. Some of other advantages are given below. 

1) By doing forging process to the parts, increase the strength of a metal object by aligning the grain of the metal in the same direction. This process is known as grain flow, making the metal stronger and less likely to break under stress.

2) Forging offers better stability during heat treatment process.

3) Forging improve the durability of a metal product by making it more resistant to wear and tear. this is because forging creates a denser metal less likely to be damaged by repeated use. 

4) By doing forging process, the final product required fewer secondary operations than other manufacturing processes. This is because forging do not require as much material to be removed during the manufacturing process, which reduces waste and saves on overall production cost.  

5) Forging enhanced the aesthetics of a metal product by creating a smoother surface finish. This is because forging eliminates any imperfection in the metal, resulting in a more polished and professional piece. 

6) Forging can allow for greater precision, because of forging have more control over the shapes of the metal parts during the forging process. As such, they can make more precise pieces with accurate tolerance.                       

Disadvantages Of Forgings Process 

                              The forging process as opposed to machining, is that it requires much more energy and time than it does. This means that production costs can be higher, making it difficult for small businesses to afford the process in some cases. Not all metals can be forged, only certain material, such as steel and aluminium, will respond well to this type of metal working process. Some of other disadvantages are given below.

1) Forging produces harmful emissions if proper safety precautions are not taken. 

2) Forging process is a time consuming process, as it often requires multiple steps. 

3) Forged products more robust than those made with other methods. Due to this we can't change the shape and dimensions of product, once product is forged. 

4) In forging process it is difficult to perform secondary operations.

5) It is difficult to maintain close tolerances. 

6) Rapid oxidation in in forging of metal surface at high temperature results in scaling which wears the dies. 

7) Forging is limited to simple shapes and has limitations for parts having undercuts. 

8) Some materials are not readily worked by forging. 

9) The initial cost of forging dies and the cost of their maintenance is high.

10) The metals get cracked or distorted if worked below a specified temperature limit. 

Conclusion

                              In above article we understand the meaning of forging, Types of forgings as the application of metal products, applications of forging, and advantages & disadvantages of forging process. If any one have new points so kindly suggest us. We hope this article is very helpful to understand the forging process.