A typical metric fastener size is a. M8*1 b. 3.4M c. 10 UNC d. 10 LH
The Correct Answer and Explanation is :
The correct answer is a. M8*1.
Here’s a breakdown of what this metric fastener size means:
- M81: This is a typical metric fastener size. The “M” denotes a metric thread, and the number following the “M” (in this case, “8”) indicates the nominal diameter of the fastener in millimeters. The asterisk “” separates the diameter from the pitch (the distance between threads). The “1” refers to the pitch of the thread, meaning the distance between the threads is 1 millimeter.
- Metric System: This fastener is part of the ISO metric system, which is the most commonly used thread standard worldwide for bolts, screws, and nuts. The threads on metric fasteners are defined by two parameters: diameter and pitch.
- Why other options are incorrect:
- b. 3.4M: This is not a standard fastener size. While it starts with “M”, the number “3.4” does not correspond to a common metric fastener size. Standard sizes typically follow a more consistent numerical pattern, like M6, M8, M10, etc.
- c. 10 UNC: This refers to a Unified National Coarse (UNC) thread, which is part of the Imperial system, not the metric system. UNC threads are commonly used in the U.S. but differ from metric threads in terms of diameter and pitch. The “10” indicates the size, but it is not a metric thread specification.
- d. 10 LH: This indicates a left-hand thread, where the threads spiral in the opposite direction compared to right-hand threads. While “LH” is an important modifier for specific applications, it doesn’t refer to the basic size of a fastener.
- Application of M8*1:
- M8 fasteners are widely used in automotive, machinery, and construction applications due to their strength and versatility. The 1mm pitch means the fastener provides a balance between strength and ease of threading.
In summary, M8*1 is the correct answer because it follows the metric thread standard, indicating a fastener with an 8mm diameter and 1mm thread pitch, a commonly used size in many industries.