This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Blanking and Piercing”.
1. Blanking is an operation in which the desired part is the sheet left out after making a punch hole in it.
a) True
b) False
View Answer
Explanation: Blanking is a kind of shearing operation which is generally carried out along a closed contour. In this operation, the required part is the material inside the sheared contour which is called as blank. For example, circular blanks are taken out from the metal sheet for subsequent deep drawing of cups.
2. Die punch clearance is generally very critical for blanking as well as for punching operation.
a) True
b) False
View Answer
Explanation: Punching is basically a kind of shearing operation in which the required part is the sheet left out after making a punch hole in the metal sheet. This method is also known as contour shearing. Die punch clearance is generally very critical for blanking as well as for punching operation, as it maintains the kind of finish obtained on the final part.
3. In blanking operation, the clearance is provided on the die for obtaining the blank from metal sheet.
a) True
b) False
View Answer
Explanation: In the blanking or punching operation, the punch diameter should be smaller than the die hole. The clearance between the die and the punch basically depends on the type of process used. For example, for blanking operation, the clearance is provided on the punch for obtaining the blank from metal sheet.
4. Fine blanking is a finishing operation in which shearing is done with very small clearances.
a) True
b) False
View Answer
Explanation: Fine blanking is normally a single step finishing operation in which shearing is done with very small clearances nearly about one percent. Close tolerances are provided in order to achieve dimensional accuracy in the operation. In this process, smooth edges are produced by the application of clamping force on the blank which also avoids the distortion of sheet during operation.
5. Which of the following parts is used for holding the metal sheet during blanking operation?
a) Spherical steel ball
b) Roller
c) Pressure pad
d) Magnet
View Answer
Explanation: A pressure pad or a hold down ring with v-shaped projection is used for holding the metal sheet tightly during the blanking operation. This pressure pad is mainly used at the bottom side of the metal sheet. A triple action press, punch and pressure pad are the main equipment used for the blanking operation.
6. Which of the following represents the approximate percentage of metal loss during the blanking operation?
a) 2%
b) 5%
c) 10%
d) 30%
View Answer
Explanation: In the blanking operation, the material loss is approximately 30 % of the metal sheet used in the cutting off operations. To reduce the waste or metal loss, the shapes to be cut are arranged on the metal sheet properly, this process of reducing metal loss is called as nesting. Nowadays, CAD software is used for this purpose.
7. A power press machine is used in the blanking operation through which a punch is attached.
a) True
b) False
View Answer
Explanation: In the blanking operation, the main function of the punch is to strike the metal sheet, which is attached to the hub of the power press machine. The striking power is mainly dependent on the capacity of machine used. The punch is attached through the machine by means of tapering at its top locked by a nut.
8. Forming dies are generally used in the blanking and piercing operations.
a) True
b) False
View Answer
Explanation: Forming dies are used for changing the shape of the blank without removing any material. For example, drawing dies and bending dies are forming dies. For blanking and piercing operations, cutting dies are used to cut the metal from the metal sheet. They basically use cutting and shearing action for cutting the material.
9. Progressive die is a die which can perform two or more operations in a single stroke.
a) True
b) False
View Answer
Explanation: Progressive die is also called a follow on die. It can perform two or more operations in a single stroke of a ram. Normally, the first operation is punching which is then followed by the blanking operation. The metal sheet is transferred to the next place in between the stroke to form a complete specimen.
10. Which of the following dies is not the type of cutting dies in the metal cutting operations?
a) Squeezing dies
b) Blanking dies
c) Piercing dies
d) Notching dies
View Answer
Explanation: Blanking dies, piercing dies and notching dies are widely used in the metal cutting operations. But the squeezing die is a type of forming die which is used for performing metal forming operations. In metal forming, drawing dies and bending dies are also used for the forming of metal sheets.
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