What is the top surface that joins two sides of a thread in a screw called?

The top surface that joins two sides of a thread in a screw is referred to as the crest. In the context of screw threads, the crest is the highest point of the thread profile. This is significant because the design of the crest affects how the screw engages with materials it is driving into, influencing the overall strength, grip, and efficiency of the fastening.

In practical applications, understanding the characteristics of the crest is crucial for ensuring that threads provide adequate contact and support when joining materials. This is particularly important in mechanical designs where load distribution and the ability to withstand shear and tensile forces are essential for product performance and safety.

While the other terms mentioned can be related to different aspects of thread geometry, they do not specifically denote the topmost part of the thread profile. The pitch refers to the distance between threads, the top flank describes the angle of the surface leading to the crest, and the top land is the flat surface at the top of the thread, which is distinct from the crest itself. Therefore, the designation of the crest is accurate when describing the top surface that connects the sides of a thread in screw design.