Forging MCQ Quiz - Objective Question with Answer for Forging - Download Free PDF

Explanation:

Upsetting

• Upsetting is a forging process in which the cross-sectional area of a metal piece is increased by compressive forces, which results in a corresponding reduction in its length. This process is one of the fundamental metalworking operations and is widely used in the manufacturing industry to produce components such as bolts, rivets, and other fasteners.
• Upsetting involves applying compressive forces to a heated or cold workpiece, typically using a die or hammer. The material is plastically deformed, causing it to bulge or expand in a specific region. This deformation is achieved without compromising the integrity of the material, and the process is designed to achieve precise dimensional control.

Steps Involved in Upsetting:

1. Preparation: The workpiece is prepared by cutting it to the desired length and heating it to the appropriate temperature (if hot forging is used).
2. Positioning: The workpiece is placed in the die or between the hammer and anvil in the desired position.
3. Application of Force: Compressive force is applied to the end or middle of the workpiece, depending on the design requirements. This force causes the material to expand in the desired direction.
4. Finishing: The deformed workpiece is removed from the die, and any excess material is trimmed or machined to achieve the final shape.

Applications:

• Manufacturing of bolts, rivets, and other fasteners.
• Production of gear blanks and flanges.
• Creation of components for automotive, aerospace, and construction industries.

Explanation:

Die Forging:

• Die forging, also known as drop forging, is a manufacturing process where a hammer is used to shape metal by deforming it between two dies.
• The metal workpiece is placed on the anvil, and the hammer is dropped onto it, causing the metal to flow and fill the shape of the die cavity.
• In die forging, the primary purpose of the anvil is to provide a solid, stable surface against which the metal can be shaped.
• The anvil serves as a foundational support that absorbs the impact of the hammer blows and ensures that the metal workpiece remains in place during the forging process.
• This stability is crucial for achieving precise and consistent deformation of the metal.

Working Principle:

• The process begins with heating the metal workpiece to a temperature where it becomes malleable. The heated metal is then placed on the anvil, and the upper die (attached to the hammer) is aligned above it. When the hammer is dropped, the force of the impact causes the metal to flow and fill the cavity of the die, taking on its shape. The anvil absorbs the impact and provides resistance, ensuring that the metal is properly deformed.

Advantages of Using an Anvil in Die Forging:

• Stability: The anvil provides a stable and sturdy surface that ensures the metal workpiece remains in place during the forging process. This stability is essential for achieving precise and consistent shapes.
• Absorption of Impact: The anvil absorbs the impact of the hammer blows, preventing excessive vibrations and ensuring that the force is effectively transferred to the metal workpiece.
• Support: The anvil supports the metal workpiece, allowing it to be deformed accurately according to the shape of the die cavity.

Applications: Die forging using a hammer and anvil is commonly used in various industries to produce components with high strength and durability. Typical applications include automotive parts, aerospace components, tools, and machinery parts.

Concept:

In a forging process

Volume before forging = Volume after forging

In the case of cylinder 

πd12h1 = πd22h2

where d1 = initial diameter, d2 = final diameter, h1 = initial height, h2 = final height

Calculation:

Given:

d1 = 20 mm, h1 = 100 mm, h2 = 50 mm

Volume before forging = Volume after forging

\(π d_1^2\;{h_1} = π d_2^2\;{h_2}\)

\({d_2} = {d_1} \times \sqrt {\frac{{{h_1}}}{{{h_2}}}}\)

\({d_2} = 20 \times \sqrt {\frac{{100}}{{50}}} = 28.28\)

\({\rm{Percentage\;change\;in\;diameter}} = \frac{{{{\rm{d}}_2} - {{\rm{d}}_1}}}{{{{\rm{d}}_1}}} \times 100 = \frac{{28.28 - 20}}{{20}} \times 100 = 41.42{\rm{\;\% }}\)

Explanation:

Cold Working:

• Plastic deformation of metals below the recrystallization temperature is known as cold working
• It is generally performed at room temperature
• In some cases, slightly elevated temperatures may be used to provide increased ductility and reduced strength

Hot Working:

• Plastic deformation of metal carried out at a temperature above the recrystallization temperature is called hot working
• Under the action of heat and force, when the atoms of metal reach a certain higher energy level, the new crystals start forming; This is called recrystallization
• When this happens, the old grain structure deformed by previously carried out mechanical working no longer exist, instead new crystals which are strain-free are formed

Warm Working:

• Metal deformation carried out at temperatures intermediate to hot and cold forming is called Warm Forming

Explanation:

• In swaging, also known as rotary swaging or radial forging, a rod or tube is reduced in diameter by the reciprocating radial movement of two or four dies.

• In this process, the diameter of a rod or a tube is reduced by forcing it into a confining die.
• A set of reciprocation dies provides radial blows to cause the metal to flow inward and acquire the form of the die cavity.
• The die movements may be of in – and – out type or rotary.
• The workpiece is held stationary and the dies rotate, the dies strike the workpiece at a rate as high as 10 - 20 strokes per second.
• Swaging is used to reduce the diameter of a tube or a rod at the end of the workpiece to create a tapered section.
• A mandrel is required to control the shape and size of the internal diameter of tubular parts during swaging.

Smaller foundries generally prefer the crucible furnace. The crucible is generally heated by electric resistance or gas flame.

In these, the metal is placed in a crucible of refractory metal and the heating is done to the crucible thus there is no direct contact between the flame and the metal charge.

This type of melting is very flexible since it suits a variety of casting alloys.

A crucible is a container that can withstand very high temperatures and is used for metal, glass, and pigment production.

Foundry crucibles are made of either ceramics or graphite depending on the requirement.

Explanation:

The fullering is done to draw out the material. In the fullering, the material is distributed away from the forging area. Fullering is the process of reducing the cross-section of the workpiece or lengthening a preparation of the stock in preparation for the subsequent operation. In other words fullering is done to reduce cross-section and increase length.

Explanation:

Forging:

Forging may be defined as a metal-working process by which metals and alloys are plastically deformed to the desired shapes by the application of a compressive force.

Basic forging operation:

Operation	Meaning
Upsetting	When a piece of stock is worked in such a way that its length is shortened and either or both its thickness and width (or diameter of a circular stock) increased, the piece is said to be upset and the operation is known as upsetting.
Heading	When the upsetting is done in such a way that the section of the stock is increased only on one end of the stock, the operation is called heading.
Fullering	It is the operation of reducing the cross-sectional between the two ends of the stock at a central place, so as to increase its length.
Edging	The function of edging or rolling operation is to distribute the metal longitudinally by moving metal from the portion of the stock where it is in excess to the portion which is deficient in metal.
Drawing down	Drawing down or “Cogging” is an operation similar to fullering with the difference that the stock is reduced at only one end (and its length increased) instead of at a central place as in fullering.

Explanation:

Forging is the process by which a metallic part is deformed to final shape with the application of pressure and with or without the application of heat. Forging involves the application of compressive stress which exceeds the flow stress of the metal. This stress is applied either quickly or slowly.

Advantages of Forging

• Strength and toughness are high
• As forged parts have a high strength to weight ratio, the material required to produce a component is less
• Internal defects like segregation, cracks, and porosity are eliminated
• Forged parts have the ability to withstand higher loads during service
• Components can be produced to close tolerances
• Machining time after forging is reduced considerably

Disadvantages of Forging

• Brittle materials like cast iron cannot be forged
• The cost of forging dies is high
• Complex shapes can easily be produced by casting and not by forging
• Small components can easily be machined from regular sections

Explanation:

Forging:

Forging may be defined as a metalworking process by which metals and alloys are plastically deformed to the desired shape by the application of a compressive force.

Different mechanical properties are:

• Plasticity: It is the property of a material by virtue of which a material deforms permanently.
  • This property of the material is necessary for forging in stamping images on coins and in ornament work.
• Elasticity: It is the property of a material by virtue of which it is able to regain its shape when the load is removed from it.
• Ductility: It is the property of a material by virtue of which it can be drawn into wires.
• Malleability: It is the property of a material by virtue of which it is able to flatten into thin sheets without cracking by a compressive force.
• Strength: It is the property of a material by virtue of which it is able to resist any deformation under loading.
• Hardness: It is resistance to penetration, scratching, abrasion or cutting.
• Toughness: It is the ability of a material to withstand both plastic and elastic deformation.
  • It is the amount of energy a material can absorb before an actual fracture.
• Brittleness: A material is brittle if when subjected to stress, it breaks without significant plastic deformation.
• Fatigue: The ability of a material to fracture by means of progressive fracture under repeated cyclic stresses of an intensity considerably below the normal strength.
• Creep: It is the permanent elongation of a component under a static load maintained for a period of time.
• Impact strength: It is the ability of a material to withstand a suddenly applied load.

Explanation:-

from the above diagram it is clearly shown that anvil is not a part of hammer.

Forging

The forging process is a metal working process by which metals or alloys are plastically deformed to the desired shapes by a compressive force applied with the help of a pair of dies. 

Explanation:

Simple dies are also known as single operation dies as a single operation is performed for each stroke of the die press.

Progressive dies which performed two or more operations at different stages every time the ram descends.

Compound dies differs from a progressive die in that it performs two or more cutting operations during one stroke of the press at one station only. These dies allow simultaneous cutting of internal as well as external part features in a single stroke in some cases.

Combination dies combine cutting operations with a non-cutting operation. The cutting operations may include blanking, piercing, trimming, and cut off and are combined with non-cutting operations which may include bending, extruding, embossing, and forming

Concept:

Advantages of Forging

• Mechanical properties and reliability of the materials increase due to the improvement in the crystal structure
• Forging reduces the grain size of the metal, which increases strength and toughness
• Fatigue and creep strength increases
• Improved physical property

Disadvantages of Forging

• Tooling cost in forging is more
• Poor dimensional accuracy and surface finish
• Forging operations are limited to simple shapes and have limitations for parts having undercuts, re‐entrant surfaces, etc

Explanation:

Hot rolling

• Hot-working is the metal processing that is done above re-crystallization temperatures of metal.
• For the manufacturing of railways tracks stainless steel is used & it is manufactured using on I-section hot rolling as shown below.
• In the process of hot-working, plasticity of rail components increase and its tendency to fracture decrease.

Forging

Forging is the process by which a metallic part is deformed to final shape with the application of pressure and with or without the application of heat.

Forging involves the application of compressive stress which exceeds the flow stress of the metal. This stress is applied either quickly or slowly.

The following are the major advantage of forging:

• During forging the pores and inclusions, if they are there; they are closed and homogenized. So, it improves the density and the soundness of the products which are made by the forging process.
• Forged parts have high mechanical and dynamic strength due to process-related grain refinement and unbroken grain flow, therefore it offers great resistance to impact and fatigue loads.
• The parts are almost free of pores and shrink holes. This results in a higher mechanical load capacity of the parts.
• Forgings are invariably produced by the hot-working process and this controls the resultant structure and properties.
• Forging can produce parts with high strength to weight ratio.
• Forging processes are very economical for moderate to high volume productions.

Swaging

In swaging, also known as rotary swaging or radial forging, a rod or tube is reduced in diameter by the reciprocating radial movement of two or four dies.

• In this process, the diameter of a rod or a tube is reduced by forcing it into a confining die.
• A set of reciprocation dies provides radial blows to cause the metal to flow inward and acquire the form of the die cavity.
• The die movements may be of in – and – out type or rotary.
• The workpiece is held stationary and the dies rotate, the dies strike the workpiece at a rate as high as 10 - 20 strokes per second.
• Swaging is used to reduce the diameter of a tube or a rod at the end of the workpiece to create a tapered section.
• A mandrel is required to control the shape and size of the internal diameter of tubular parts during swaging.

 

Concept:

Coining:  It is a cold press working operation in which the starting material is in the form of a blank of sheet metal. Coining is a pressing operation, it does not base on metal deformation.

It is essentially a cold forging operation except for the fact that the flow of metal occurs only at the top layers and not the entire volume.

Coining is a simple application of closed die forging in which fine details in the die impression are impressed into the top or/and bottom surfaces of the workpiece.

Coining is the operation of the production of coins, medals, or other ornamental parts by squeezing operations.