What is the distance measured perpendicular to the axis between the crest of the thread and the root of its mating thread in a thread assembly of screws called?

The distance measured perpendicular to the axis between the crest of the thread and the root of its mating thread in a thread assembly is known as crest clearance. This measurement is significant as it affects the fit between mating threads, ensuring that there is adequate space for engagement without causing excessive friction or wear during operation. Proper crest clearance is essential for achieving the desired performance in a threaded assembly, as it influences factors such as load distribution, strength, and fatigue life.

Crest clearance plays a crucial role in preventing cross-threading and ensuring a smooth and effective assembly of parts. Understanding this concept is vital for engineers and designers when specifying thread dimensions to achieve optimal performance in their mechanical designs.