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Metric Threads

A metric thread is a type of screw thread that is based on the metric system of measurement. Metric threads are used in a wide variety of applications, including machine tools, automobiles, and furniture.

History of Metric Threads

The history of metric threads can be traced back to the early 1800s. In 1841, British engineer Joseph Whitworth developed a new type of screw thread that was based on the decimal system. Whitworth's thread quickly became popular in Great Britain, and it was eventually adopted by other countries as well.

In the late 1800s, the metric system was beginning to gain popularity in Europe. In 1876, the Swiss government adopted a metric thread standard that was based on Whitworth's design. This standard was eventually adopted by other European countries, and it became the basis for the modern metric thread standard.

Where and Why Metric Threads are Used

Metric threads are used in a wide variety of applications. They are commonly used in machine tools, automobiles, and furniture. Metric threads are also used in a variety of other applications, such as medical devices, aerospace, and electronics.

Metric threads are used for a variety of reasons. They are often used because they are easy to manufacture and they are compatible with other metric components. Metric threads are also often used because they are strong and durable.

Specific Standards Where Metric Threads are Defined

The most common standard for metric threads is ISO 68. This standard defines the geometry and dimensions of metric threads. ISO 68 is an international standard, and it is widely used in countries around the world.

There are a number of other standards that define metric threads. These standards include:

ISO 724: This standard defines the tolerances for metric threads.
ISO 965: This standard defines the symbols used to designate metric threads.
ISO 1478: This standard defines the methods for measuring metric threads.

Internal Metric Threads

Internal metric threads are threads that are cut into the interior of a part. These threads are commonly used in nuts. Internal metric threads are typically identified by the letter M followed by the major diameter of the thread in millimeters. For example, an internal metric thread with a major diameter of 10 millimeters would be identified as M10. The 'M' designation indicates the major diameter of the nut (or nominal outer diameter of a screw or bolt) in millimeters. Typically the thread pitch (the distance between thread peaks) is quoted too:

M10x1.5

This means it has a 10mm diameter with a 1.5mm thread pitch.

The thread is a symmetric V shaped thread with the flanks having an angle of 60°.

Conclusion

Metric threads are a versatile type of screw thread that is used in a wide variety of applications. They are easy to manufacture, strong, and durable. Metric threads are also compatible with other metric components.