Differentiating the Metric International Standard Screw from the Whitworth Thread Screw - Communist China.

A threaded nail is a screw. It can be 1nter-changed with another screw and can be taken off easily. It joins parts of a machine together. It is not only widely used in the machine production industry but also very commonly used in tools of our daily life. China is now promoting the use of international standard screws threaded bolts. The standards proclaimed by the governinent for screws threaded bolts, and screw nuts and the standards proclaimed by ministries for screw threads are based on the metric system and not the Whitworth system. However, owing to old habits and the need to maintain and repair old machines, screws of the metric and the Whitworth systems are still on sale in markets. The basic difference between the metric and the whitworth screws is in the screw threads. These that have metric standard threads are called metric scrcws, while those that have Whitworth standard threads are called Whitworth screws.