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The correct ANSWER is (a) True

The explanation: In precision type forging OPERATION, the volume of the metal stock and the dies are controlled very TIGHTLY. Such operations are called as precision forging which is a modern technique of forging. Metal PARTS of better strength, high QUALITY details, and complex shape can be easily produced by the forging operation.

Correct answer is (a) True

The explanation is: CUTTING dies are mainly used for cutting the METAL. They use shearing action for cutting the metal SHEET. VARIOUS cutting dies are used such as blanking dies, piercing dies, PERFORATING dies, notching dies, shaving dies and nibbling dies. And it is not possible to use cutting dies for the metal drawing operations.

Right answer is (b) False

The best I can EXPLAIN: Tensile strength of any material is defined as the ability of a material to resist axial or centric load without FAILURE, it is mainly determined by performing tensile test. When EQUAL and opposite forces are applied to the material SIMULTANEOUSLY that axially pulls the material, which further CAUSES elongation of the material by decrease in its diameter.

Right option is (c) Shearing

To explain: In the electromagnetic forming process, electromagnetic formation MAINLY used for three forming methods which can be compression, expansion, and COUNTER forming. For compression, a TUBULAR metal is compressed by a COIL, usually against a grooved tube. And shearing is a DIFFERENT process which is not a part of electromagnetic forming.

Right answer is (B) False

Explanation: PLASTIC DEFORMATION of any material means permanent deformation without the presence of external constraints. The plastic deformation of crystalline materials GENERALLY takes place by processes which are very different from that for the amorphous materials. In plastic deformation, material cannot regain its original SHAPE.

Right OPTION is (a) True

To elaborate: In electromagnetic FORMING, many components like capacitor bank, forming coil, field shaper, conductive MATERIAL etc. are used to create intense magnetic FIELDS. This magnetic is generally produced by the discharge of capacitors into a coil, which lasts only for a few microseconds. Then further processing is done to perform the metal forming.

Correct choice is (b) False

The explanation is: In the hot working of materials, the POROSITY always decreases and reaches to negligible amount in the material. The HIGH TEMPERATURE of the material makes dynamic changes in the material and the gases ENTRAPPED in the material LOSES out and vapourized due to the high temperature of material. This minimizes the amount of porosity in the material.

Correct choice is (a) True

The EXPLANATION is: In the yield criteria of any metal, von-mises criterion is also known as distortion ENERGY THEORY. This theory shows that the plastic DEFORMATION of metal occurs when the value of shear STRAIN energy per unit volume of the body becomes equals to the strain energy per unit volume at the elastic limit of the metal.

Right OPTION is (a) True

The explanation is: In metal forming process, plastic DEFORMATION of the material is compulsory. It is a process in which the required SHAPE of metal is achieved by plastic deformation. Stresses are induced in the metal which is greater than its yield strength but LESS than its fracture strength so that the metal can be deformed into the required shape.

Right answer is (a) True

To elaborate: In hot working of materials, it is possible to continuously reform the grains in material. It requires proper CONTROLLING of temperature and RATE of hot working. In hot working, very favourable GRAIN size can be OBTAINED which further enhances the mechanical properties of material. And no any residual stresses are present in the material during hot working which also GIVES rise to better mechanical properties.

The correct OPTION is (b) False

The best I can explain: When an axial LOAD is applied to the material, the material first elongates, then necking occurs and the fracture is produced. The necking PHENOMENON is only occurring in the tensile test due to the elongation of material, a neck like structure is FORMED. Its behaviour generally depends on the material used for the test. Necking does not take place in brittle materials.

Right answer is (a) True

For explanation: The behaviour of the material is completely DEFINED by its stiffness. Such material directly fractures without yielding when it REACHES ultimate strength material. These materials are called as brittle materials. Examples of brittle material are ceramics, cast iron, etc. These materials are not suitable for FORMING operation, where permanent plastic deformation is required to GET the final product.

The correct choice is (b) False

The best I can explain: The fluids reveal their flow behaviour only when it is subjected to SHEARING stress. A little amount of shear stress can DEFORM the flow and it never regains its original shape EVEN after REMOVING the shearing load. The compressive or TENSILE stress does not make any changes to the fluid behaviour.

The correct answer is (b) False

Explanation: Friction and lubrication in METAL FORMING are greatly influenced by parameters such as temperature, mechanical properties, surface finish, sliding velocity, PRESSURE etc. In general, the viscosity of LUBRICANT DECREASES with the increase in temperature and vice-versa. And friction becomes more vigorous when the temperature is very high during the metal forming operation.

The CORRECT choice is (a) True

Easiest explanation: In plastic DEFORMATION of metal, its strength DECREASES when the TEMPERATURE is increased. The plasticity of material is better when the deformation temperature is greater than the re-crystallization temperature but should be below the melting point. Re-crystallization temperature is the temperature at which the metal shows enough plasticity for efficient deformation.

The CORRECT choice is (b) False

The EXPLANATION: In sheet metal forming or cutting OPERATIONS, die punch clearance is present which basically used to govern the kind of finish obtained on the FINAL part. Die punch clearance is very critical in operations like blanking and punching because it involves very close tolerances which give accurate and precise details on the finished part.

Correct answer is (c) Tensile force

Easiest EXPLANATION: Tensile force is the predominant force in most of the sheet metal forming operations as compared to the bulk forming which basically INVOLVES COMPRESSIVE forces. DUE to the tensile stresses in the metal sheets, they may experience localized deformation which is further followed by CRACKING.

Correct answer is (C) Sheet metal FORMING and cutting

Easiest explanation: Sheet metal forming and cutting PROCESSES are widely used for the manufacturing of home appliances like fridge, vacuum cleaner radio, toys, dryers etc. In the sheet metal forming processes, bending OPERATION is TAKES place which form the metal and sheet cutting is used for shearing out the metal part from the large metal sheet.

Right answer is (d) No spring-back

Easiest explanation: In the electromagnetic forming PROCESS, the METAL is loaded and achieve plastic REGION, which RESULTS in plastic or PERMANENT deformation, so that the spring-back associated with the mechanical forming process is completely eliminated because no any mechanical contact is present during the process of metal forming.

Right answer is (a) True

Explanation: In METAL forming process, several types of ADDITIVES are mixed with lubricant to enhance the performance of the lubricant. The EXTREME pressure (EP) additives are generally USED in heavy work metal operations. The temperature dependent EP additives, such as chlorine, phosphorus, and SULPHUR are mainly used to create chemical films that prevent metal to metal contact during forming operations.

The correct option is (a) True

The BEST I can explain: In strip DRAWING test method, a strip is used which drawn between two opposite PLANE dies that are wider than the strip. The amount of stretching strip can change the coefficient of friction. And the test is usually performed with different SPEEDS and different radius of the die. This test is widely used for evaluating the characteristics of LUBRICANTS which used during the process of metal forming.

Right option is (b) False

Easiest explanation: In lubrication, the hydrocarbon layers are meant to REDUCE the friction and wear under loading conditions. In the case of un-reactive contacting SURFACES, the FATTY acids only adhere by physical adsorption. For the reactive METAL surfaces, the mechanism of chemical adsorption is LIKELY to occur, which combines both the physical and chemical adsorption.

The CORRECT option is (a) True

Explanation: In the orbital forging process, forming is done to the meat PART by using a cone-shaped DIE that is simultaneously ROLLED and pressed into the material. The METAL part is supported on a lower die, because of inclined axis of cone. In the process, only a small area of the metal surface is compressed at the stage of forming.

Correct answer is (b) False

The explanation: When a MATERIAL is SUBJECTED to any LOAD then the stress is induced in the material which is not a material PROPERTY, it basically depends on the load applied and the cross-sectional area of the material. And young’s modulus is a material property which indicates stiffness of the material and it is different for different materials.

Right option is (a) True

For explanation I WOULD say: Metal FORGING is a forming operation that performs hammering to shape the metal component. In forging PROCESS, the metal component is HEATED sufficiently, and then it is hammered by using a hammer which can be performed manually or by automation, depending on the scale of production and properties required in the forged metal component.

The correct answer is (b) False

For explanation I would say: In the electromagnetic forming process, the metal absorbs ENERGY from the magnetic field to GET deformed. To utilize most of this energy to forming operation, and to reduce the energy loss due to resistance heating, the forming pulse is kept short for better OPTIMIZATION of energy produced by the magnetic field. In GENERAL, pulse has duration of between 10 and 100 SECOND.

Correct answer is (a) True

Explanation: In the electromagnetic forming process, the conductivity of the METAL and the eddy CURRENTS which makes contact with MAGNETIC field creates a NET pressure on the surface of the metal. Then the metal surface moves inward due to the effect of this pressure, this mainly occurs due to the TRANSFER of energy from the magnetic field to the metal.

The CORRECT choice is (a) True

Explanation: In the metal FORMING and cutting operations, transfer dies are almost similar to progressive dies, the only difference is that the already cut blanks are fed from the STATION to station manually or by automation. In the OPERATION, first the blanking is PERFORMED which is then followed by the piercing process.

Correct choice is (a) True

To ELABORATE: In the hot WORKING of metals, rapid oxidation or scale FORMATION and surface de-carburization processes occur on the surface of metal due to the presence of HIGH temperature. This results in a poor surface finish of the metal and the metal loss too. But in cold working, the temperature is kept MODERATE which maintains the better surface finish of the metal.

Right choice is (b) False

For explanation: In the stress-strain CURVE, beyond the tensile strength, the LOAD carrying capacity reduces and the test material goes through a localized elongation called NECKING. There is no any CONSTANT strain in this region and the elongation occurs in one small segment of specimen. The stress measured just before the FAILURE is known as the fracture stress.

Right option is (b) False

Best explanation: FORGING is a metal forming OPERATION in which heated metal is beaten by a hammer to give it the desired shape. It is basically a deformation PROCESS in which the MATERIAL is compressed between dies by using impact load to deform it. Forging can also be used for making complex shapes of metal parts.

The correct choice is (a) True

Easiest explanation: In lubrication, the performance of boundary layers and its formation basically depends on its physical and chemical adsorption. The boundary layers formed by a MECHANISM MAINLY consist of clusters and LONG chain hydrocarbons with a polar head. Then this polar group adheres to the surface and forms high viscosity HYDROCARBON layers.

Correct ANSWER is (b) False

Easiest explanation: The main function of the lubricant is to CONTROL the frictional force that arises due to sliding contact between the sheet metal and CUTTING TOOL material during sheet metal forming operation. Lubricants are also used to prevent galling problems by protecting tool material from DIRECT contact with the sheet material.

The correct option is (a) True

Explanation: SHEAR stress basically involves an APPLICATION of load parallel to the surface of material in the opposite direction. The relationship between the shear stress-strain is similar to the flow curve for the plasticity of material. The applied load ALWAYS increases as the increase in its strain hardening; then the material becomes much stronger and HARDER.

The correct choice is (a) True

Explanation: When a material is subjected to a load, then the amount of strain that the material sustains before failure is an important property which is called as ductility of the material. This property is very USEFUL in manufacturing of machine PRODUCTS which WORKS more dynamically than statically. The ductility is generally measured in TERMS of its area reduction.

Correct answer is (b) False

Best explanation: Material ALWAYS shows a non-recoverable deformation when it is SUBJECTED to STRESSES beyond certain minimum stress. Crystalline materials experience permanent deformation when slipping occurs ALONG the definite crystalline planes. But in amorphous materials, permanent deformation occurs when the GROUP of atoms or molecules slides past each other.

The correct choice is (b) False

To explain: The raw material for the sheet METAL forming is basically the OUTPUT of the rolling process. IN the sheet metal forming process, flat rectangular solid sheets of STANDARD sized are used and then the operations like piercing or blanking is performed on the metal sheets to obtain the desired output.

The correct option is (B) False

Best EXPLANATION: In the electromagnetic forming process, eddy currents are induced in a conductive material that is placed near to the coil. Then it interacts with a magnetic field to cause mutual repulsion between the metal and the forming coil. This FORCE of repulsion is mainly responsible for inducing stresses in the metal BEYOND its yield strength which RESULTS in plastic deformation of metal.

Correct OPTION is (a) True

The best explanation: In an open DIE forging process, the metal billet is heated up to a very high TEMPERATURE and then compressed between two flat die halves. This method is like a compression test, which is ALSO known as upsetting or upset forging. In the process, billet is basically deformed by a decrease in its height and increase in its DIAMETER.

The correct answer is (b) False

The explanation is: Forming dies and PROGRESSIVE dies are DIFFERENT from each other. Progressive dies can perform two or more operations in a single stroke in different stages in which mainly cutting operations like blanking and punching are performed. And forming dies are only used for forming operations.

Right option is (a) True

Easiest EXPLANATION: When the hot working process is properly carried out, then hot WORK does not affect the mechanical properties like tensile strength, hardness, CORROSION resistance, etc. The shear stress is reduced at the HIGHER TEMPERATURE, so this process does not require much force to obtain the desired deformation, due to this properties remains same.

Correct choice is (a) True

For explanation I would say: Hot WORKING or hot forming of materials is normally performed at the TEMPERATURE above than its re-crystallization temperature, but for materials LIKE lead (PB) and tin (Sn), the hot working can be DONE at room temperature because these materials possess very low crystallization temperature.

Right CHOICE is (b) False

Easiest explanation: The flow of material in die cavity not only depends on the flow-ability of material, it also depends on the frictional conditions at the die and material interface. Therefore, a PROPER study of parameters that AFFECT the friction is required for SELECTING suitable lubricants for the OPERATION and producing better quality of metal parts.

The correct choice is (a) True

The best I can explain: In the cold WORKING of MATERIAL, the material is deformed plastically which increases the strain HARDENING. This further increases its strength by LOSING its ductility; the loss of ductility is useful in machining operation. The breaking of chips BECOMES much easier due to less ductility, which further facilitates the cutting operation of material.

Correct answer is (b) False

The BEST explanation: The mechanical properties, elongation and izod values are enhanced in the hot working of materials. In hot working, the other properties LIKE directional properties and fibre are also PRODUCED in the material which helps in achieving the larger DEFORMATION more rapidly than that obtained by the cold working, as the material is present in the plastic STATE.