Fasteners include bolts, screws, studs, washers, nuts, etc. There are many different kinds of fasteners, which are suitable for a variety of applications. The information below will help with better identifying and understanding different types of fasteners. 

1. What are some types of fasteners?

-  Bolt:

Bolts consist of a head and a cylindrical body with external threads. They are used in combination with nuts for fastening multiple parts together. This type of connection is called a bolted joint or bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, making this a “detachable connection.”

-  Stud:

A stud is a type of fastener without a head, exhibiting only external threads. To use a stud, one end is screwed into a part with an internally threaded hole, and the other end passes through a part with a through hole. Next, a nut is threaded onto the end, allowing the parts to be securely connected. This type of detachable connection is called a stud connection. Studs are usually used with thick parts in structures with limited space, or if a bolt connection is not suitable.

-  Screw:

Screws consist of a head and a cylindrical body with external threads. Screws can be divided into three categories: machine screws, set screws, and screws for special purposes. Machine screws are typically used for connecting a part with a threaded hole and one with a through. This is a type of detachable connection called a screw connection. Note that machine screws can also be used with a nut when connecting multiple parts with through holes. Set screws are typically used to fix the relative position of two parts. Special purpose screws, such as hoisting ring screws, can be used for hoisting parts. 

-  Nut:

Nuts exhibit internally threaded holes and typically have a hexagonal or square cross-section. Nuts are used in combination with bolts, studs, or machine screws for fastening multiple parts together. 

-  Self-Tapping Screw:

These fasteners are similar to machine screws, but the threads allow the screw to “tap” a hole. The screw material is harder than the part material, allowing it to carve threads into a hole in the part. These screws are typically used with parts of thinner material and offer a detachable connection.

-  Washer:

An annular fastener that is placed between a bolt, screw, or nut and the part to be fastened.  The washer serves to increase the surface area between the connecting parts, reduce pressure on the joint, and protect the surfaces of the connecting components.

-  Retaining Ring:

Retaining rings are used in machine equipment to prevent components from moving relative to one another. They are typically installed in a groove in either the shaft or hole.

-  Pin:

Pins have cylindrical bodies and are typically used for locating one part relative to another. They can also be used for transferring power or locking other fasteners.

-  Rivet:

Rivets consist of a head, body, and rod and are used to fasten multiple parts together. This type of joint is called a rivet joint and is a non-detachable connection. Rivets must be destroyed to separate the joined parts. 

-  Assemblies and Connecting Pairs:

Assembly parts consist of multiple fasteners that are supplied together. Examples include machine screws supplied with washers (flat washers, spring washers, lock washers, etc.). Connecting pairs are fasteners that are supplied in combination with special bolts, nuts, and washers, such as high-strength, large hexagonal head bolts used in steel structures. 

-  Welding Fastener:

A welding fastener consists of a nailing rod or nailing head, which is welded to a part for further connection with other parts.

2. What causes fasteners to rust?

Several factors can contribute to fastener corrosion. When electroplating fasteners, if the drying process has not completed, residual water vapor may accumulate and lead to corrosion. Similarly, after drying and packaging, condensate may form on the packaged parts. This exposure to water causes a chemical reaction, resulting in the fastener rusting. Long-term storage in damp environments may also lead to corrosion, as well as poor or insufficiently thick application of electroplating material.

To mitigate corrosion, ensure that the fasteners have undergone the proper electroplating process. Store fasteners in a dry environment that is properly ventilated, and avoid storing them on the ground. Try to avoid installing fasteners in areas with excessive moisture, humidity, salinity, acidity, and temperature.