Hexagon screw size standard specification


Everyone is very familiar with the screw, which is basically the most basic small part we use. In China, the screw standard is stipulated according to our own standard parts. So for this hexagonal screw, it What is the size? What is the difference between the inner hexagonal screws and outer hexagonal screws we usually mention? Today, I will give you a detailed introduction on this issue. Let's take a look at the size standards and specifications of hexagonal screws. Go! Friends in need can collect it.

Hexagon Head Bolt standard

National standard GB/T5782-86 for external hexagonal bolts

The standard stipulates that the thread specifications are M3~M64, A and B-level hexagon head bolts. A-level is used for bolts with D<=24 and L<=10D or L<=150mm (according to the smaller value); B-level is used for Bolts with D>24 or L>10D or L>150 (according to the smaller value).

Hexagon Head Bolt size

External Hexagon Head Bolt standard: DIN ANSI BS GB Material: stainless steel or carbon steel or specified Diameter: 5mm~20mm, 1/4″~3/4″ Length: 8mm~200mm, 5/16″~8″ Thread: metric, Coarse teeth, fine teeth, imperial mechanical properties: 4.8, 5.8, 6.8, 8.8, 9.8, 10.9, 12.9 Surface treatment: natural color, galvanized, blackened, nickel-plated

How to measure:

First, measure the total length L of the hexagon socket head screw with a vernier caliper, and then measure the length l of the bolt head. In this way, the total length L-l is the length of the screw. Hexagon socket head cap screws, also referred to as hexagon socket cap screws, cup head screws, and hexagon socket cap screws, are called differently, but they represent the same meaning. The national standard national standard for hexagon socket head screws is the national standard GB70.1-2000. 3*25, 3*30, 3*45, 4*8, 4*10, 4*12, 4*16, 4*20, 4*25, 4*30, 4*35, 4*45, 5* 10, 5*12, 5*16, 5*20, 5*25, 6*12, 6*14, 6*16, 6*25, 8*14, 8*16, 8*20, 8*25, 8*30, 8*35, 8*40, etc.


There is a standard for external hexagonal bolt standards, which is grade standard, which is divided into grade 4.8 and grade 8.8. These two levels are used a lot in the market. Especially the 4.8 grade outer hexagonal bolts. Because he is much cheaper than 8.8 grade Hexagon Head Bolts. Of course, it is more widely used. But for demanding products. Because of its high requirements in various aspects such as hardness. This requires the use of grade 8.8 hexagon bolts. 8.8 level six

What is the difference between inner hexagon screws and outer hexagon screws

The outer edge of the screw head of the inner hexagonal screw is round, and the middle is a concave hexagonal shape, while the outer hexagonal screw is the kind of hexagonal screw with hexagonal sides of the screw head that we usually see.

The main difference:

Hexagon socket screws are often used in machinery, mainly with the advantages of easy fastening and disassembly, and not easy to slip. The inner hexagonal wrench is generally in the shape of a curved ruler with a 90°turn. The long end is divided into a round head (a hexagonal cylinder is similar to a sphere) and a flat head. The round head can be easily obliquely inserted and disassembled, and it can be installed in some parts that are inconvenient to use a wrench. The manufacturing cost of the outer hexagon screw is much lower than that of the inner hexagon. Its advantage is that the screw head (where the wrench is stressed) is thinner than the inner hexagon, and some places cannot be replaced by the inner hexagon. In addition, machines with low cost, low power strength and low precision requirements use much fewer inner hexagonal screws than outer hexagonal screws.