This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Thread Rolling”.
1. Thread rolling is a kind of metal forming which is essentially a hot forging operation.
a) True
b) False
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Explanation: Thread rolling is basically a kind of metal forming process which is essentially a cold forging operation. In this process, thread rolls are used which forced onto the component that prepared at the pitch diameter of the required thread. This method is widely used for manufacturing the bolts which combine with nut, and used for temporary joining.
2. In thread rolling, all thread forms can be produced in a single pass.
a) True
b) False
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Explanation: In thread rolling, a complete thread is generally formed where the grain of the material follows the form or shape of the thread, which considerably increases the strength of the thread. In this method, all thread forms can be formed in a single pass, which basically includes buttress, knuckle and trapezoidal threads.
3. In general, thread rolling process is very slow and uneconomical process.
a) True
b) False
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Explanation: Thread rolling process is very fast and it can produce threads on the bolt extremely fast. So this process can form hundreds of bolts in few minutes. And this process is highly economical for producing threads on the bolts. However, the process is costly, but best suited for large scale production of bolts.
4. Thread rolling process can exceed the length of rolling material during the operation.
a) True
b) False
View Answer
Explanation: In thread rolling, threaded rollers are used which forces their thread into the rolling material. And the threads are formed on the material, which then comes out from the machine. The thread is formed on the bolt, but this process does not exceed the length of rolling bolt during the operation.
5. The operating speed of thread rolling is much faster than that of thread cutting process.
a) True
b) False
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Explanation: In thread rolling process, the process is carried out at much faster rate than the thread cutting process. This basically reduces the machine cycle time. In this process, the blank is produced at the pitch diameter of the thread, but in cut threads the blank is prepared at the major diameter. So, more material is required during the process.
6. Thread rolling process cannot maintain accuracy in producing the threads during the operation.
a) True
b) False
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Explanation: In thread rolling process, it has inherent ability to maintain the accuracy in the production of threaded bolts. It can maintain high level of accuracy; this is basically due to well and precise settlement of machine parts during high speed production. Thread rolling also provides better finishing to the formed materials.
7. Thread rolling enables the thread to withstand high tensile and fatigue loads.
a) True
b) False
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Explanation: The thread rolling process is also called as cold forging or work hardening process. This process enables the thread to withstand high tensile and fatigue loads. Work hardening is basically done which also improves the wear characteristics of threaded material by inducing the strength and hardness properties in the material.
8. In thread rolling process, the selected blank should be of appropriate diameter.
a) True
b) False
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Explanation: In thread rolling, it is very important that the diameter of the selected blank should be correct. If the blank is undersize then the effective diameter of the thread may formed, but the major diameter cannot be formed. And if the blank is oversize, then the excess of material would be forced into the rolls, which may further cause damage to the rolls.
9. In thread rolling, the chamfer diameter should be greater than the core diameter of the thread.
a) True
b) False
View Answer
Explanation: In general, the selected blank should be straight and possess better surface finish for the process of thread rolling. In this process, a chamfer is used which generally present at the start of the blank and also at the end when the thread is to end at an undercut. The selected chamfer diameter should be slightly less than the core diameter of the thread for taking place of efficient operation.
10. In thread rolling, the rolling speed only depends on the tensile strength of the material being rolled.
a) True
b) False
View Answer
Explanation: It is very important to select appropriate rolling speed in thread rolling process to produce products of better thread quality and for long life of the rolls. The rolling speed mainly depends on the tensile strength, the speed capabilities of the machine and the thread form to be rolled. In general, the rolling speed kept is very high. But if the speed is too low, then it may cause damage to the rolls.
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