Subject: Manufacturing Process I
Unit 2: Metal Forming Processes
Unit 2 Part 3: Forging Process
Forging
It is a forming process in which the raw material is heated to plastic state & it is deformed between a pair of dies by application of pressure to transform it into desired shape permanently.
Note
Forging is generally a hot working Process. Pressure applied is forging process by - Hand Hammer & Power Hammer.
Types of Forging
Depending upon the means of application of pressure forging process can be of two types, as –
Hand Forging
Machine Forging
Machine forging can further be classified into following two types:
Drop Forging &
Press Forging.
Hand Forging
It is a forging process in which the raw material is heated in an open fire and shaped gradually by hammering with manual hammer using basic tools, is called hand forging or, black smith forging.
The hand forging process is useful for small scale productions. In this process, products of simple shape & small size can be produced.
Applications of Hand Forging
Axes, sickles, ploughshares, hoes, knives, scissors etc.
Machine Forging
It is a forging process in which the raw material is heated in a furnace and shaped by applying pressure between a pair of dies using various hand tools and Dies.
This is useful for large or medium scale productions. Forging Press hammer is controlled by Mechanical or Hydraulic Mechanisms.
Machine Forging Applications
Automotive components such as Crankshafts, connecting rods etc.
Pipes, flanges, and other fittings used in piping systems.
Drop Forging
In drop forging the upper die is fixed with the drop hammer and bottom die is fixed with the anvil. In this process, the drop hammer strikes the workpiece repeatedly in quick succession until the material is completely deformed.
Press Forging
In press forging the upper die is fixed with the hammer and bottom die is fixed with the anvil. The hammer presses the workpiece gradually, until the material is completely deformed and the dies closes on each other.
Types of Forging based on types of dies used
Open Die Forging
Impression Die
Closed Die Forging
Open Die Forging
When the forging is carried out by placing the workpiece between a pair of dies that do not close on each other.
Closed Die Forging: When the forging is carried out by placing the workpiece between a pair of dies that completely closes on each other.
Impression Die Forging
It is a type of closed die forging in which one or more than one impression is created on the workpiece by closed die forging process.
If only one impression is created by this process then it is called Single Impression forging.
If more than one impression is created at a time by this process then it is called Multi Impression forging.
Types of Forging Presses and Hammers
Spring Hammer
Drop Hammer
Spring Hammer
Spring hammer is commonly used for small forgings. It is a light load type of power hammer. Spring hammers may be made available in various capacities having the tup weights from 30 to 250 kg.
Drop Hammer
Drop hammers are operated hydraulically and are widely used for shaping parts by drop hammering a workpiece. A drop hammer raises a massive weight and allows it to fall under gravity on dies.
Forging Defects
Unfilled Section: This defect occurs when parts of the forging are not completely filled with material, often due to insufficient raw material or poor die design.
Die Shift: Misalignment between the upper and lower dies, resulting in a shift in the forged part.
Surface Cracking: Cracks that appear on the surface of the forging, often due to excessive load.
