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Small Knowledge of Bolt Classification

Mar. 09, 2020 | 00:00:00
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This time Fastener Bolt Exporter talks about bolt information other than threads. There are many types of bolts, and there are probably several classification methods: classification by the head of the bolt; classification by the material; classification by the performance level; classification by the connection force method.


The first category is classified by the head of the bolt. There are also two types of heads, namely head shape and tightening method.


Hexagonal Nut


Hexagonal Nut


First, classification by head shape

1.Hexagonal Nut (the most common hexagon bolt-external hexagon bolt);

2. Round head bolts (the most common round head bolts in the picture-hexagon socket head bolts);

3. Flat head bolts (Flat head bolts are also called countersunk head bolts, the picture shows common flat head cross bolts);

4. T-bolts and square-head bolts (the two are very similar, but not the same. The heads of T-bolts are rectangular, and the heads of square bolts are square);

5. Headless screw (pictured is the hexagon socket headless screw);

6. Stud bolts.

(2) Classification by screwing method

1. Hexagon bolt

2. Hexagon bolts;

3.Flat bolt

4. Cross bolts;

5. Outer Torx Bolt;

6.Plum blossom bolt

Some of the Torx head bolts are very special. The Torx head of the high-strength bolt is broken because the torque when it is broken is the designed maximum torque. Not twisting means that the torque is not enough.


Second category is by material. At present, the standard parts on the market are mainly carbon steel, stainless steel and copper.

(A) carbon steel

We distinguish low carbon steel, medium carbon steel and high carbon steel and alloy steel by the content of carbon in carbon steel.

(Two) stainless steel

Performance level: 45, 50, 60, 70, 80

(Three) copper

Common materials are brass ... zinc-copper alloy. H62, H65, H68 copper are mainly used as standard parts on the market.


Third, largest classification, by performance level

Structural connection bolt performance grades are divided into 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and more than 10 grades, of which bolts of grade 8.8 and above are made of low carbon alloy steel or medium carbon steel and heat treated Quenching, tempering), commonly known as high-strength bolts, the rest are commonly known as ordinary bolts. The bolt performance grade label consists of two parts of numbers, which represent the nominal tensile strength value and yield ratio of the bolt material, respectively.


Of course, there are not only so many types of bolts, but also bolts with gaskets, bolts with multiple tightening methods, bolts with gaskets, and various special-shaped bolts. Bolts serve as industrial meters. It plays an irreplaceable role in industry.