suitable heading given below for each paragraph

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8) Closed Die Forging
9) Metalworking with the Application of Force or Pressure
METALWORKING FORMING PROCESSES
Modern metalworking processes, though diverse and specialized, can be 
categorized as forming, cutting, and joining processes. Forming processes 
are supposed to be classified in different ways. One way of classification in-
cludes casting, bulk forming processes, and sheet forming processes. Another 
way embraces casting, metalworking with the application of force or pressure, 
powder metallurgy. The latter is considered more common.
Casting is known to involve pouring heated liquid material into a mold 
which contains a hollow cavity of the desired shape, and then allowing it to 
cool and to solidify. The solidified part, a casting, is ejected or broken out of 
the mold to complete the process. There are numerous metal casting tech-
niques but over 70% of all metal castings are produced in foundries via a sand 
casting process, which is characterized by using sand as the mold material.
All technological processes of metalworking with the application of force 
or pressure are known to be divided into final metallurgy processes (rolling, 
extrusion, drawing); workpieces and machine parts manufacturing processes 
(open die forging, impression die forging, closed die forging, sheet metal form-
ing, etc.).
Forging is considered to produce a piece, a forging, that is stronger than 
an equivalent casting as it improves the mechanical properties of metals by 
minimizing the internal grain size in metal under controlled plastic deforma-
tion. Forging processes can be performed at various temperatures; they are 
generally classified by whether the metal temperature is above or below the 
recrystallization temperature. There are different kinds of forging operations 
available: drawing out (the workpiece length increases and its cross section 
decreases), upsetting (the workpiece length decreases and its cross section in-
creases), squeezing in closed compression dies (it produces multidirectional 
flow), etc. Most forging operations use metal-forming dies. Dies must be pre-
cisely designed and carefully heat-treated to shape correctly the workpiece and 
withstand the tremendous forces and pressure. 
Open die forging uses flat and shaped dies with almost no limit in size of 
forgings ranging from a few up to several hundred thousand kilograms but re-
quiring their considerable machining to achieve the final shape. 
In impression die forging, a metal workpiece is placed in a die resembling a 
mold which is attached to the anvil. The hammer die is usually shaped as well. 
The hammer is dropped on the workpiece to make the metal flow and fill the 
die cavities. Excess metal flows out of the die and forms flash. The flash cools 
more rapidly than the rest of the material so it helps prevent from forming 

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more flash and also forces the metal to fill completely the die cavity. In the end 
of this operation the flash is removed. 
A variation of impression die forging is believed to be flashless forging, or 
true closed die forging. In this type of forging the die cavities are completely 
closed to keep the workpiece from forming flash. The major advantage of this 
process is that there is little or no escape of excess metal. The disadvantages in-
clude additional cost due to a more complex die design and the need for better 
lubrication and workpiece placement. 
There is a variety of sheet metal forming manufacturing processes, such as 
stamping, punching, bending, etc. These types of forming processes are per-
formed at room temperature. However, some recent developments involve the 
heating of dies or workpieces. Sheet metal forming is characterized by the fact 
that the thickness of the sheet metal changes little while processing. 
Metal components can also be formed by using metal powder instead 
of molten metal, billets, bars or ingots. The powder is placed into a die and 
compressed into a solid mass, and then it is heated until the powder particles 
join together structurally. This process is often called sintering. Besides, metal 
powder can be shaped by rolling, extruding, etc.

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