How to distinguish between bolts, screws, and screws?
Aug 12, 2025
In everyday life, we often mention bolts, screws, and screws, but what's the difference between them? Actually, the standard term doesn't distinguish between screws and nuts. "Screw" is a common name; anything with external threads can be called a "screw." Nuts are typically hexagonal in shape with internal threads, used to mate with bolts and tighten components. "Nut" is a common name; the standard term should be "nut."
A bolt typically has a hexagonal head and an externally threaded shank. Screws are smaller and come in various shapes, such as flat and cross heads, with externally threaded shanks. A stud should actually be called a "double-ended stud," with external threads on both ends and a plain shank in the middle. The long threaded end is used to connect to a deep hole, while the shorter end connects to the nut.
Standard fasteners are divided into twelve categories, and selection is determined based on the application and function of the fastener.
1. Bolts
Bolts are widely used in mechanical manufacturing for removable connections and are typically used in conjunction with a nut (often with one or two washers). 2. Nut
3. Screw
Screws are usually used alone (sometimes with washers) for fastening or securing purposes and should be screwed into the internal threads of a machine body.
4. Stud
Studs are often used when one of the connected parts is thick, a compact structure is required, or frequent disassembly makes bolted connections unsuitable. Studs are typically threaded on both ends (single-ended studs are threaded on one end). One end is typically screwed firmly into the component body, while the other end mates with a nut, providing both connection and fastening, but also serves a significant purpose as a distance gauge.
5. Wood Screw
Wood screws are used to screw into wood for fastening or securing purposes.
6. Self-tapping Screw
The working screw hole for self-tapping screws does not require pre-tap; the internal threads are formed as the self-tapping screw is inserted.
7. Washer
Lock Washer
Washers are placed between the bearing surface of bolts, screws, and nuts and the bearing surface of the workpiece to prevent loosening and reduce stress on the bearing surface. Locking Washer
8. Retaining Ring
Retaining rings are primarily used to position, lock, or prevent parts from moving back on shafts or in holes.
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9. Pins
Pins are commonly used for positioning, but can also be used to connect or lock parts, and can also serve as overload shear elements in safety devices.
10. Rivets
Rivets have a head at one end and an unthreaded shank. To use, the shank is inserted into the hole of the connected part, and the end of the shank is then riveted together to achieve a connection or fastening.
11. Joint Pair
A joint pair is a combination of a screw, bolt, or self-tapping screw and a washer. After the washer is installed on the screw (or bolt), it must rotate freely on the screw (or bolt) without falling off. It primarily serves a fastening or securing function.
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