Parts and names of screws
Every shape of a screw all has meaning!
The complex shape of a screw all has meaning. Here, we will explain the various parts and names of screws, as well as their dimensions.
① Drive section
The hole for inserting a screwdriver, etc., is called the “drive section”. There are many shapes other than the standard cross-shaped hole (+ hole), including one-way drive sections that can only be turned in the direction of tightening, and there are also some that break if a certain amount of force is applied.
② Head
The head of a screw has the role of fixing the screw in place so that it does not get screwed in too far. The most common shape is a flat head, but there are also thinly made heads that do not protrude when screwed in,heads with a loosening prevention effect, etc.
③ Screw thread
When we think of screws, we think of this jagged shape. This is called the ‘screw thread’ and is the most important part of the screw. There are many types of screw thread, including those that prevent loosening and those that make screwing in easier.
④ Point
The tip of the screw is called the “point”, and this also has meaning. Basically, the shape changes depending on the mating material (fastening material). Types include the “cone point”, which makes it easier to screw in, and the “rounded end”, which does not damage the mating material.
Commonly used names and dimensions
◆Pitch
| In screw standards, pitch refers to the distance between adjacent screw threads. In the case of metric screws, sizes are written in millimeters. |  |
◆Nominal diameter
| This refers to the external shape of the screw. The standard size of the major diameter is mainly used. Screws are referred to as M2 screws, M3 screws, M4 screws, M5 screws, etc. The M indicates that they are metric screws, and the number is the nominal diameter of the screw, i.e. the major diameter. The major diameter is the diameter of the shaft with the screw thread, not the diameter of the screw head. |  |
◆Minor diameter
This is the diameter of the imaginary circle that touches the thread's valley diameter.
◆Pitch diameter
This is the diameter of the imaginary circle where the width of the screw groove is equal to the width of the screw thread.
◆Thread angle
This is the angle of the screw thread. The angle of the thread on a standard screw (small screw) is 60 degrees.
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