1. Classification of fasteners
There are many types of fasteners, which can be mainly divided into the following categories according to shape and function:
Bolt: A cylindrical fastener with threads, usually used in conjunction with a nut, to achieve a tightening effect by rotating the nut. Bolts are widely used in various mechanical equipment and structures, and are important components for connecting and fixing parts.
Nut: A nut is a component used in conjunction with a bolt, which has threaded holes inside that match the bolt thread. By rotating the nut, it is possible to tighten or loosen the bolt.
Screw: A screw is a type of fastener with external threads, usually screwed directly into the threaded hole of the connected part without the need for a nut to fit. Screws can serve both fastening and positioning purposes during the connection process.
Stud: A stud is a type of fastener with threads on both ends, typically used to connect two thicker components. The fastening effect of the bolts is stable and suitable for situations where they can withstand high tensile forces.
Gasket: A gasket is a component used to increase the contact area between connecting parts, prevent loosening, and reduce wear. Gaskets are usually used in conjunction with fasteners such as bolts and nuts.
Self tapping screw: Self tapping screw is a type of screw with special threads that can directly tap threaded holes into the connected part and achieve fastening. Self tapping screws are widely used for connecting thin plate materials.
Rivet: A rivet is a fastener that connects two or more components together by riveting. The riveted connectors have high strength and stability.
Sales: Sales are fasteners used to connect and position two components. Sales typically have smaller diameters and longer lengths, making them suitable for situations that require precise positioning.
Retaining ring: A retaining ring is a component used to prevent axial movement of a shaft or its components. A retaining ring is usually installed on the end face of a shaft or hole, limiting the axial movement of the shaft or its components through its elasticity or rigidity.
Wood screws: Wood screws are fasteners specifically used to connect wood. The thread of wood screws is shallow, easy to screw into wood, and has a good fastening effect.
Welding nail: Welding nail is a high-strength, fast welding fastener suitable for various steel structure construction and industrial manufacturing fields. It consists of a bare rod and a nail head (or a structure without a nail head), which is fixedly connected to a certain part or component through welding technology for stable connection and assembly with other parts in the future.
Assembly: A component formed by combining multiple parts together. These components can be standard parts or specially designed parts. The purpose of the assembly is to facilitate installation, maintenance, or improve production efficiency. For example, combining bolts, nuts, and washers together to form a fastening assembly that can be quickly installed.
2. Principles for determining standards and varieties
When selecting fasteners, we need to follow the following principles to determine their standards and varieties:
Reduce variety and improve efficiency: While meeting usage requirements, standard fasteners should be selected as much as possible to reduce variety and specifications and improve production efficiency.
Prioritize the use of standard product varieties: Standard product varieties have high universality and interchangeability, which can reduce production and maintenance costs. Therefore, whenever possible, priority should be given to using standard components of the product.
Determine the variety according to the usage requirements: When selecting fasteners, full consideration should be given to their usage environment, stress conditions, materials, and other factors to ensure that the selected fasteners can meet the usage requirements.
3. Mechanical performance level
The mechanical performance level of fasteners is an important indicator for measuring their strength and durability. According to GB/T 3098.1-2010, bolts, screws and other fasteners can be classified into multiple performance levels such as 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9, etc. These grades represent the tensile strength and yield strength of fasteners under different stress conditions. For example, a bolt with a performance level of 8.8 represents a tensile strength of 800 MPa and a yield strength of 80%, which is a tensile strength of 640 MPa.
4. Accuracy level
The precision level of fasteners reflects their manufacturing accuracy and fitting accuracy. According to the standard regulations, fastener products can be classified into three levels: A, B, and C. Among them, A level has the highest accuracy and C level has the lowest accuracy. When selecting fasteners, their accuracy level should be determined according to the usage requirements.
5. Thread
Threads are an important component of fasteners, and their shape and size have a significant impact on the connection effect of fasteners. According to the standard regulations, the tolerance level of threads can be divided into 6H, 7H, etc. Coarse thread has good universality and interchangeability, suitable for general connection occasions; Fine thread has good anti loosening performance and is suitable for situations that require withstanding large vibrations and impacts.
6. Specifications
The specifications of fasteners usually include two parameters: diameter and length. When selecting fasteners, it is advisable to choose diameters and lengths within the standard specification range to reduce inventory and production costs. At the same time, for the selection of diameter, the first series of values should be chosen as much as possible to improve the universality and interchangeability of fasteners.
In summary, fasteners, as important components for connecting and fixing parts, play a crucial role in industrial production. By understanding the classification, selection principles, and related technical parameters of fasteners, we can better choose and use fasteners. That concludes today’s sharing. Thank you very much for your attention and reading.
Post time: Jan-06-2025