Basic Introduction to Fastener Threads
Basic Introduction to Fastener Threads
1Root
The deepest part of the groove, located between two adjacent flanks.
2
Crest
Crest
The highest point of the thread, typically parallel to the axis of the screw.
3
Helix Angle
Helix Angle
The angle formed by the helix of the thread with a plane perpendicular to the screw axis.
4
Thread Angle
Thread Angle
The angle between the flanks of the thread. The standard metric thread angle is 60°.
5
Flank
Flank
The sloping surface of the thread that connects the crest and the root.
6
Pitch
Pitch
The distance from a point on one thread to the corresponding point on the next thread.
7
Depth
Depth
The distance between the crest and the root, measured perpendicular to the axis.
8
Minor Diameter
Minor Diameter
The smallest diameter of the thread (at the root).
9
Pitch Diameter
Pitch Diameter
An imaginary cylinder diameter located between the major and minor diameters; also known as the effective diameter.
10
Major Diameter
Major Diameter
The largest diameter of the thread, measured at the outermost edge.
11
Axis
Axis
An imaginary line running longitudinally through the center of the screw.
The above technical information is for reference only.