Bolts, screws, and nuts are frequently mentioned in daily life, but what are the differences among them? In fact, there is no specific term for “screws” and “nuts” in standard terminology. The colloquial term “screw” is commonly used for any component with external threads. Nuts typically have a hexagonal shape with an internal thread, designed to complement bolts and secure related components. Similarly, the colloquial term “nut” is commonly used for what should be technically referred to as a “nut.”

Bolts typically have a hexagonal head and an externally threaded shaft. Screws, on the other hand, are smaller, with various head types such as flathead or Phillips, and an externally threaded shaft. The term “screw column” should technically be referred to as a “double-headed screw column,” with threads at both ends and a smooth shaft in the middle. The longer threaded end is used for deep-hole connections, while the shorter end connects to a nut.

Standard fasteners are divided into twelve categories, selected based on their application and functionality.

Bolt: Widely used in mechanical manufacturing for detachable connections, usually paired with a nut.

Nut: Used to complement bolts and secure related components.

din 7985 pan head machine screw
din 7985 pan head machine screw
standard: din 7985
Materail: sainless steel 304
Surface finish: Plain
property class ( grade ) : A2-70
Head type: pan head
Drive type: phillips ( cross )

Screw: Typically used individually for fastening or fixing, requiring insertion into the internal thread of a structure.
Column Screw: Used for connecting thicker components where bolt connections may not be suitable due to compact structures or frequent disassembly.

 wood screw
Wood Screw: Used for fastening into wood, providing a connecting or securing function.

Self-Tapping Screw: Paired with a working screw hole that doesn’t require pre-threading, forming internal threads while being screwed in.

Anti-loosening Washer: Placed between the support surfaces of bolts, screws, and nuts to prevent loosening and reduce stress on the support surfaces.
Locking Washer: Used to lock the position of components.
Retaining Ring: Used for positioning, locking, or preventing movement of components on a shaft or in a hole.
Industrial Pin: Primarily used for positioning and can also serve as a connecting or locking element, functioning as a safety device with overload shearing capabilities.
Rivet: One end has a head, and the shaft is threadless, inserted into a hole in the connected component, and the end is riveted for connection or fixation.
Connection Pair: A combination of screws, bolts, or self-tapping screws and washers used for fastening or locking components. The washer, when placed behind the screw, must be able to rotate freely on the screw (or bolt) without falling off.