Hexagonal turned screws and bolts

Definition and shape
Hexagonal turned screws and bolts are a common fastener. The head is in the shape of a regular hexagon. This shape is designed mainly to facilitate the use of tools for tightening or loosening operations. Usually, a wrench can be used to clamp the hexagonal shape of the head so that the rotation force can be evenly distributed on the bolt head. , thereby effectively tightening or removing bolts.
Turning is one of the main processing methods. Through the turning process, the outer dimensions of the bolt can be made more precise and the surface smoother. During the turning process, the raw material (usually a bar) gradually forms the shape of the bolt, including the threaded portion and head, under the rotation of the lathe and the cutting action of the tool.
Materials and performance
Material type:
Carbon Steel: This is one of the most commonly used materials. Hexagonal turned screws and bolts made of carbon steel have high strength and hardness and can withstand large tensile and shear forces. For example, in the connection of building structures, carbon steel bolts can firmly connect steel beams, steel columns and other components. The properties of carbon steel bolts vary depending on the carbon content. Bolts with higher carbon content are stronger but may be slightly less tough.
Stainless steel: Bolts made of stainless steel have excellent corrosion resistance and are suitable for use in humid and corrosive environments. For example, in food processing equipment, medical equipment, outdoor facilities, etc., stainless steel bolts can prevent rust and ensure the hygienic and long-term stable operation of the equipment. Common stainless steel models are 304 and 316. 316 stainless steel has stronger corrosion resistance and is especially suitable for highly corrosive places such as marine environments.
Alloy steel: Alloy steel bolts contain a variety of alloy elements, such as chromium, molybdenum, nickel, etc. The addition of these elements can significantly improve the strength, toughness, wear resistance and other properties of the bolts. For example, in some mechanical equipment with high strength requirements, such as large machine tools, automobile engines, etc., alloy steel bolts can withstand complex stress conditions and ensure the safe operation of the equipment.
Mechanical properties:
Strength grade: Hexagonal turning screws and bolts have different strength grades, such as grade 4.8, grade 8.8, grade 10.9, grade 12.9, etc. The classification of strength grades is mainly determined based on the tensile strength and yield strength of bolts. Taking grade 8.8 bolts as an example, their tensile strength is generally not less than 800MPa and their yield strength is not less than 640MPa. The higher the strength grade, the greater the load the bolt can withstand, but the corresponding cost may also increase.
Toughness: In addition to strength, the toughness of the bolt is also important. Bolts with good toughness are not prone to brittle fracture when subjected to impact loads or alternating loads. For example, in some mechanical devices with large vibrations, such as engines, compressors, etc., bolts with good toughness need to be used to ensure that they will not be damaged by vibration during long-term operation.
Dimensions
Thread specifications: including two main thread specification systems: metric and inch. Metric threads such as M3, M4, M5, etc. (where M represents metric thread, and the number represents the nominal diameter of the thread), while inch threads have specifications such as 1/4 inch, 3/8 inch, etc. The pitch of the thread is also an important dimensional parameter, which determines the density of the thread. For example, the standard pitch of M5 thread is 0.8mm. Different pitches are suitable for different application scenarios. Generally speaking, the smaller the pitch, the finer the threaded connection, but the number of turns required for tightening may be more.
Bolt length: There are various length specifications, ranging from a few millimeters to tens of centimeters. The specific length is selected according to the thickness of the connecting parts in the actual application. For example, when connecting thin metal sheets, you may only need to use shorter bolts, while in the connection of building structures or large mechanical equipment, you may need to use longer bolts to penetrate multiple components and tighten them.
Head size: Since the head is a regular hexagon, the distance between its opposite sides is an important size parameter. This size matches the size of the wrench used, for example, for an M8 hexagonal bolt, the head-to-edge distance is typically about 13mm, allowing a 13mm wrench to be used.

Machinery manufacturing: widely used in the assembly of various mechanical products. For example, in the connection of machine tool beds, worktables, spindles and other components, hexagonal turning screws and bolts can provide reliable fastening force to ensure the accuracy and stability of the machine tool during processing. In automobile manufacturing, it is used for the assembly of engines, transmissions, chassis and other components to ensure the safety and reliability of automobiles.
Construction industry: used for the connection of building structures, such as the connection of steel beams and steel columns in steel structure buildings, and the connection of embedded parts and other metal parts in concrete structures. During the installation of building curtain walls, hexagonal turning screws and bolts are also used to fix the curtain wall keels and panels to ensure the firmness and safety of the curtain wall.
Electrical equipment: In the assembly of chassis and cabinets of electrical equipment, it is used to fix various electrical components and circuit boards. For example, in the assembly of large server cabinets, bolts can firmly fix server motherboards, hard disk trays and other components in the cabinet, while making it easier for maintenance personnel to disassemble and maintain.