Grade intensity
Hexagon bolts are classified according to the hardness of a screw wire, tensile strength, yield strength, etc., that is, the level of hexagon socket bolts. Different grades of hexagon bolts are required for different product materials. What are the grades of hexagon bolts?
Hexagon socket bolts are divided into ordinary and high-strength grades.
Ordinary hexagon socket bolts refer to 4.8, and high strength hexagon socket bolts refer to 8.8 or higher, including 10.9 and 12.9. Hexagon socket bolts of grade 12.9 are generally referred to as knurled, natural oily black Hexagon cup screws.
The hexagonal bolts used for the connection of steel structures have more than 10 grades of 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9, etc., of which grade 8.8 and above are made of low carbon alloy steel or medium carbon steel. After heat treatment (quenching, tempering), commonly known as high-strength bolts, the rest known as ordinary bolts.
Bolt performance grade labels are composed of two parts, which respectively indicate the nominal tensile strength value and yield ratio of the bolt material. For example, a bolt with a performance rating of 4.6 means:
1. Bolt material nominal tensile strength up to 400MPa;
2. The yield ratio of the bolt material is 0.6; the nominal yield strength of the bolt material is 400×0.6=240MPa.
Performance grade 10.9 high-strength bolts are heat treated to achieve:
1. The bolt material has a nominal tensile strength of 1000MPa;
2. The yield ratio of the bolt material is 0.9; the nominal yield strength of the bolt material is 1000×0.9=900MPa.
The meaning of the Hexagon Socket Bolt performance level is an internationally accepted standard. Bolts of the same performance level have the same performance regardless of the material and the origin of the bolt. Only the performance level can be selected for the design.
The classification of the hexagon socket bolts is basically the same. The level is different, and the prices on the market will definitely be different. The general high-strength internal hexagon bolts are definitely much more expensive than ordinary hexagon socket bolts. More commonly used in the market is still 4.8, 8.8, 10.9, 12.9 these four.
Sort by head type
Hexagon socket bolts have a variety of national standards, but there are certainly the same, are all within the hexagonal. So what is the type of Hexagon Socket Head bolt?
Hexagon socket head bolts are divided into a hexagonal head bolt with a cylindrical head. This is the most commonly used, but it also has many kinds of iron. It is divided into carbon steel and stainless steel. Stainless steel hex bolts are also available in stainless steel SUS304 and SUS202.
Hexagon socket head bolts, this is also called Pan head Hex bolts.
Hex head bolts with countersunk head, heads are flat, and the inside is hexagonal. There is also a kind of national standard that is rather special, called headless hexagon socket bolts. That is, we often call the machine screws, pay screws, set screws. This is the common name for headless hexagon socket bolts, but the meaning is the same.
Of course, there are some bolts with hexagonal plum blossom heads. The use of this is relatively small, the market is also basically difficult to see.
Hexagon socket bolts have more national standards than others, but basically they are rather special. Basically, few people on the market will use them. More used or to the number of cylindrical head Hexagon socket bolts, also known as cylindrical head Hexagon socket screws.
Production wire
Hexagon bolts, in general, there are many types of classification, we must first understand the hexagon bolt level which? In fact, it is also very simple, there are standard specifications of the ordinary hexagon socket bolts, that is to say the standard 4.8 Hexagon bolts, there are 8.8 Hexagon bolts of the standard specifications, there are also 10.9 Hexagon bolts of the standard specifications, there are also grade 12.9 Hexagon bolts are standard, 12.9 Hexagon socket bolts, 8.8 Hexagon socket bolts, and 10.9 Hexagon socket bolts. They all have high strength. The intensity factor is not visible in general.
Generally, the screws of our company, when doing hexagonal bolts, 4.8 standard hexagonal bolts are made with screw wire 1008. Grade 8.8 hexagon socket bolts are manufactured using screw wire 10B21. Grade 10.9, grade 12.9 hex bolts are manufactured using 45 gauge steel.
Under normal conditions, grade 4.8 hexagon socket bolts do not need to be hardened after being produced. Because the strength of the screw wire itself can reach 4.8, there is no need to harden it. The 8.8-level, 10.9-level, and 12.9-hexagonal bolts must be heat-treated, and the hardness of the socket-head bolts must reach a certain level by hardening. Reach the corresponding level strength.
Causes of skidding
The following are several reasons why the Hexagon screw head slips.
The first is that there may be some minor problems with the hexagon socket screws during production. This will cause the hexagonal groove to become slightly larger. After being used for a period of time, friction can cause slippage.
Secondly, the punch of the hexagon socket screw is not very good, and the other reason is that the three opposite sides of the hexagon socket of the screw are not very symmetrical, or the angle of the cone angle does not conform to the regulation during the production process, and is generally larger. Or the corners of the Hexagon Socket Screw are vague and so on. The reasons for the non-standard production are that the depth of a thimble pin is not enough, and slipping will occur.
Third, the wire material of the Allen screw is not good, which will result in the screw being softer than the hardness, and the purity of the wire is not enough. If this is the problem, then manufacturers can increase the hardness of the hardware screws by replacing the wires of the hexagon socket bolts. If you want to further prevent slippage, you can choose to electroplate after the inner hexagonal groove has been produced, preventing the hexagonal screw assembly from slipping after a long time.
Fourth, there are too many lubricating oils used in the process. This also results in slippage of the Allen screw. This is when we use the Allen screw is not appropriate, so sometimes we also need to learn a certain amount of knowledge, it can also avoid the Hexagon screw in the process of sliding.