1.
The Threads on most standard threaded fasteners are made on cold-heading machines with
Correct Answer
C. Flat thread-rolling dies
Explanation
Flat thread-rolling dies are used to create the threads on most standard threaded fasteners. These dies are designed to roll the material into the desired thread shape instead of cutting it. This rolling process results in a stronger and more precise thread compared to thread-cutting dies. The flat profile of the thread-rolling dies allows for a smoother and more consistent thread formation. Therefore, flat thread-rolling dies are preferred for creating high-quality threads on fasteners.
2.
The leargest diameter of a straight external or internal screw thread is called the
Correct Answer
B. Major diameter
Explanation
The major diameter refers to the largest diameter of a straight external or internal screw thread. It is the measurement taken across the crest of an external thread or across the root of an internal thread. This diameter is crucial in determining the size and fit of the screw thread, as it is used to calculate the pitch diameter and thread depth.
3.
The smallest diameter of a straight external or internal screw thread is called the
Correct Answer
C. Minor diameter
Explanation
The minor diameter refers to the smallest diameter of a straight external or internal screw thread. It is the measurement taken from the bottom of the thread grooves on opposite sides of the screw. This diameter is important for determining the fit and function of the screw, as it affects how tightly the screw will fit into a threaded hole or onto a threaded shaft.
4.
The diameter of a screw thread that determines the fit or clearance between mating threads is the
Correct Answer
C. Pitch diameter
Explanation
The pitch diameter of a screw thread refers to the imaginary diameter that lies exactly in the middle of the threaded portion. It is the diameter at which the width of the thread and the width of the space between threads are equal. The pitch diameter is crucial in determining the fit or clearance between mating threads as it affects the engagement and functionality of the threads. The major diameter refers to the largest diameter of the thread, the minor diameter refers to the smallest diameter of the thread, and the actual outside diameter refers to the physical measurement of the thread's outer diameter.
5.
The distance from a point on one thread to a corresponding point on the next thread is called the
Correct Answer
B. Pitch
Explanation
The distance from a point on one thread to a corresponding point on the next thread is called the pitch. The pitch refers to the axial distance between two adjacent threads on a screw or a bolt. It is a crucial measurement in determining the thread size and the functionality of the threaded connection. The pitch is typically measured in millimeters or inches and is an essential parameter in engineering and manufacturing applications involving threaded fasteners.
6.
Two ways to measure the pitch of screw threads are
Correct Answer
D. With a screw pitch gage and a rule
Explanation
The correct answer is with a screw pitch gage and a rule. A screw pitch gage is specifically designed to measure the pitch of screw threads accurately. It has a set of teeth or blades that match the shape and size of the threads, allowing for precise measurement. A rule, on the other hand, is used to measure the length or distance of an object. Therefore, using a screw pitch gage and a rule together would provide the most accurate measurement of the pitch of screw threads.
7.
The thread form that was first adopted by most american industries was the
Correct Answer
C. Unified State Standard
Explanation
The correct answer is Unified State Standard. This thread form was initially adopted by most American industries.
8.
The form of screw thread most widely used in the United States today is
Correct Answer
B. Unified
Explanation
The Unified form of screw thread is the most widely used in the United States today. This form of screw thread was developed to standardize the thread sizes and pitches across different industries and applications. It combines the best features of the American National and United States Standard thread forms, making it versatile and compatible with both internal and external threads. The Unified form has become the standard in the United States due to its widespread adoption and ease of use.
9.
The Thread angle of the Unified Screw Thread is
Correct Answer
C. 60 Degrees
Explanation
The thread angle of the Unified Screw Thread is 60 degrees. This angle is commonly used in screw threads because it provides a good balance between strength and ease of threading. A 60-degree thread angle allows for efficient engagement and disengagement of the threads, making it suitable for a wide range of applications. Additionally, this angle helps distribute the load evenly across the threads, preventing excessive stress concentration and improving the overall durability of the screw thread.
10.
The class of a Unified National Thread has to do with the
Correct Answer
B. Fit of the thread
Explanation
The class of a Unified National Thread refers to the fit of the thread. It determines how tightly or loosely the threads of a fastener will fit together. The class is denoted by a number, such as 1, 2, or 3, with class 1 being a loose fit and class 3 being a tight fit. This classification system helps ensure that threaded fasteners are compatible and can be easily assembled and disassembled.
11.
A 29-degree thread used mostly on machine tools is the
Correct Answer
C. ACME
Explanation
ACME thread is a 29-degree thread that is commonly used on machine tools. It is designed to provide a strong and durable connection, making it suitable for heavy-duty applications. The ISO Metric thread is a different type of thread that is used in metric applications. Unified National thread is used in the United States for general-purpose applications. Pipe thread is specifically used for pipe fittings. Therefore, the correct answer in this case is ACME thread.
12.
The Type of pipe thread used for general-purpose jobs that require a low-pressure seal is the American National Standard
Correct Answer
A. Taper Pipe Thread
Explanation
Taper Pipe Thread is the correct answer because it is the type of pipe thread used for general-purpose jobs that require a low-pressure seal. Taper Pipe Thread is designed to create a tight seal as the threads taper towards the end of the pipe, ensuring a secure connection. This type of thread is commonly used in plumbing and other applications where a reliable seal is necessary.
13.
ISO Inch and ISO Metric threads are not interchangeable because of differences in their
Correct Answer
D. B andC
Explanation
ISO Inch and ISO Metric threads are not interchangeable because of differences in their diameter and pitches. ISO Inch threads are measured in inches, while ISO Metric threads are measured in millimeters. The diameter and pitch of the threads are crucial in determining the compatibility and interchangeability of the threads. Therefore, due to the differences in diameter and pitches, ISO Inch and ISO Metric threads cannot be interchanged.
14.
Which ISO metric thread is commonly used on metric fasteners
Correct Answer
A. Coarse pitch
Explanation
Coarse pitch is commonly used on metric fasteners because it provides a higher thread depth, making it more suitable for applications where there is a need for strong and secure fastening. The larger thread depth allows for better load distribution and resistance to loosening due to vibrations or other external forces. Fine pitch threads, on the other hand, are used in situations where a finer adjustment or a higher level of precision is required. Constant and variable pitch threads are not commonly used on metric fasteners.
15.
How are ISO Metric threads designated on working drawings?
Correct Answer
C. With the letter M
Explanation
ISO Metric threads are designated on working drawings with the letter M. The ISO (International Organization for Standardization) Metric thread standard is widely used in many industries for screw threads. The letter M is used to indicate that the thread is in accordance with this standard.