Fastener Bolt

Fastener Bolt: A mechanical part, a cylindrical threaded fastener equipped with a nut. A type of fastener consisting of a head and a screw (cylinder with external threads). It needs to be matched with a nut and is used to fasten and connect two parts with through holes. This type of connection is called a bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.

Fastener Bolt Classification

According to the connection stress mode: it is divided into ordinary type and reamed type.
According to the shape of the head: there are hexagonal head, round head, square head, countersunk head, oval head, etc. Among them, the hexagonal head is the most commonly used. Generally, countersunk heads are used where connections are required.
According to the thread type: it is divided into two categories: coarse thread and fine thread.
Bolts are divided into eight grades according to their performance grades: 3.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9.

Application of Fastener Bolts

Fastener Bolts are widely used, and the applications of bolts include: electronic products, mechanical products, digital products, power equipment, and electromechanical machinery products. Bolts are also used in ships, vehicles, water conservancy projects, and chemical experiments.
As for engineering, construction, and bridges, large bolts and nuts are used; transportation equipment, airplanes, trams, automobiles, etc. use both large and small bolts. Bolts have important tasks in industry.

Generally, countersunk heads are used where the surface after connection is required to be smooth and without protrusions, because the countersunk heads can be screwed into the parts. The round head can also be screwed into the part. The tightening force of the square head can be higher, but the size is large. In addition, in order to meet the need for locking after installation, there are holes in the head and holes in the stem. These holes can prevent the bolts from loosening when they are vibrated.

Fastener Bolt Stress Mode:

Ordinary ones mainly carry axial forces and can also carry less demanding lateral forces.
The bolts used to ream the holes should match the size of the holes and be used when subjected to lateral forces.

Fastener Bolt Grade Meaning:

According to relevant standards, the performance grades of carbon steel and alloy steel bolts are divided into more than 10 grades, including: 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. Among them, bolts of grade 8.8 and above are made of low carbon alloy steel or medium Carbon steel and heat treatment (quenching, tempering) are commonly known as high-strength bolts and the others are ordinary bolts.

Fastener Bolt inspection is divided into two types: manual and machine

Manual is the most primitive and most commonly used method of consistent detection. In order to minimize the outflow of defective products, generally production company personnel visually inspect the products to be packaged or shipped to eliminate defective products (defects include tooth damage, mixed materials, rust, etc).

Another method is fully automatic inspection by machine, mainly magnetic particle inspection. Magnetic particle inspection uses the interaction between the leakage magnetic field and magnetic particles at bolt defects to target possible defects in bolts (such as cracks, slag inclusions, mixed materials, etc.) and the difference in magnetic permeability of steel. After magnetization, these materials are discontinuous. The magnetic field at the location will undergo rugged changes, forming a leakage magnetic field on the surface of the workpiece where part of the magnetic flux leaks, thereby attracting magnetic powder to form magnetic powder accumulation at the defect – magnetic marks. Under appropriate lighting conditions, the location and shape of the defect will be revealed. The accumulation of these magnetic particles is observed and interpreted to achieve the purpose of eliminating defective products.

–Eternal Bliss Alloy Casting & Forging Co, Ltd.

Caesar

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