"Drill tail self-tapping screw" is also called "drill tail screw" "drill tail screw" "self-drilling screw". Northerners also call it "dovetail screw". English: SELF DRILLING SCREWS. Drill tail screws can be divided into: national standard GB/T, German standard DIN, Japanese standard JIS, and standard ISO according to the implementation standards.

According to the purpose and shape, it can be divided into the following categories:
1. Cross-grooved disc head self-drilling and self-tapping screws. Implementation standard: GB/T 15856.1-2002 has the following specifications: (also known as round head drill tail)

2. Cross-groove countersunk self-drilling and self-tapping screws Implementation standard: GB/T 15856.2-2002 has the following specifications: (Also known as flat drill tail, salad head

3.  Cross-groove semi-submerged self-drilling and self-tapping screws. Implementation standard: GB/T 15856.3-2002 has the following specifications: This specification is that semi-submerged heads are rarely used in the market.

4. Hexagonal flange self-drilling and self-tapping screws are specified in GB/T 15856.4-2002. They have the following specifications: (Also known as hexagonal Dahua Si drill tail, this is a commonly used and widely used specification for drill tail screws.)

According to the material, it can be divided into: steel 1022A, stainless iron 410, stainless steel 304
1. Carbon steel drill tail screw, 1022A, standard heat-treated steel can be used as a material for drill tail screw production. After heat treatment, the surface hardness is HV560-750 and the core hardness is HV240-450. Ordinary surface treatment is easy to rust, high hardness and low cost.

2. Rust-free iron drill tail screw, 410, heat-treatable, better rust resistance than carbon steel. Worse than stainless steel.

3. Stainless steel drill tail screw, 304, cannot be heat treated, has strong rust resistance, low hardness, high cost, can only drill aluminum plate, wood board, rubber board.

4. Composite drill tail screws, the drill bit is produced using carbon steel, and the thread and head are produced using a combined 304 stainless steel process

Common materials for flange screws:
1, high carbon steel C%>0.45%. Hexagonal flange face screw product materials are basically not used in the market at present;
2. Medium carbon steel 0.25% hexagonal head screw medium carbon steel material is usually called 35-gauge and 45-gauge steel in China, and basically called 1035, CH38F, 1039, 40ACR, etc. abroad. Mainly used for grade 8 nuts, grade 8.8 bolts and grade 8.8 hexagon products;
3, mild steel C% ≤ 0.25% is commonly called A3 steel in the country. It is basically called 1008, 1015, 1018, 1022, etc. abroad. Mainly used for products without hardness requirements such as grade 4.8 bolts, grade 4 nuts, small screws, etc. ( Note: Drill nails are mainly made of 1022 material.)
4. Alloy steel: Alloy elements are added to ordinary carbon steel to increase some special properties of steel: such as 35, 40 chromium-molybdenum, SCM435, 10B38. Hexagonal flange face bolts mainly use SCM435 chromium-molybdenum alloy steel, and the main components are C, Si, Mn, P, S, Cr, and Mo.

The performance grades of flange bolts for steel structure connection 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, the bolts of grade 8.8 and above are made of low-carbon alloy steel or medium-carbon steel and heat treated (quenched and tempered). They are generally called high-strength bolts, and the rest are generally called ordinary. Ordinary bolt nail heads are very thick and difficult to deform. If they vibrate after being installed, they need to be tightened again. The flange with a thin part can be slightly deformed and locked more firmly. Also, if it goes into the hole, ordinary bolts cannot use tools. The head of the flange bolt is smaller, and the flange plate below still serves as a fastening function, but it can be used to go into the hole with tools. It has about the same principle as the Allen bolt. Another is the flange top flat pad, which is more suitable for softer, non-wear-resistant materials and will not cause perforations
A flange is a connecting device for two large-diameter pipes, usually two flange pieces plus a number of fastening bolts. Carbon steel flanges are flanges made of carbon steel. Low carbon steel has good plasticity and low strength. After adding an appropriate amount of carbon element, it will become hard, and the plasticity will be reduced and the strength will be enhanced.
The national standard numbers commonly used on the market at present are GB5789 (large head) and GB16674 instead of GB5787 (small head)

Contour screws and plug screws are also called shoulder screws, stop screws, stop bolts, brake bolts, etc.; plug screws are used in conjunction with bolt tie rods and are mainly mold accessories used to control the mold opening stroke between the mold base plate, runner push plate and mold template in the three-plate mold. Because it can be set to the parting surface of the mold, the mold design can be miniaturized. This type of product has high hardness, good toughness, wear resistance and heat resistance, is suitable for molds, and can significantly increase their service life. In particular, the thermal shape of the mold has become effectively controlled, making it suitable for molds in high-temperature working environments. Plug screw composition properties Material: SCM435, hardness: 33～38HRC.
The height screws used in plastic molds are generally used as the top rod screws. The height screws can ensure that the top plate can move parallel and will not break due to uneven force on the top rod due to tilt
The following are the standards used to check the specifications of height screws: GB52, GB6170, GB6172 and DIN934. The main differences between them are: GB6170 is thicker than GB52, GB6172 and DIN934, commonly known as thick nuts.
In addition, there are differences in the opposite sides. In the M8 nut series, the opposite sides of DIN934, GB6170, and GB6172 are all 13MM, which is 1MM smaller than the opposite side of GB52, which is 14MM smaller. In the M10 nut series, the opposite sides of DIN934, GB6170, and GB6172 are 13MM smaller than the opposite side of GB52, which is 1MM smaller than the opposite side of GB52, which is 14MM smaller. In the M10 nut series, the opposite sides of DIN934 and GB52 are 17MM smaller than the opposite sides of GB6170 and GB6172, which is 1MM larger than the opposite sides of GB52, which is 1MM smaller than the opposite side of GB52, which is 14MM smaller. In the M10 nut series, the opposite sides of DIN934 and GB6172 are 13MM smaller than the opposite side of GB52, which is The opposite side of GB52 is 19 MM, which is 1 MM larger than the opposite side of GB6170 and GB6172, which is 18 MM.
For the screw cap of M14, the opposite side of DIN934 and GB52 is 22MM, which is 1MM larger than the opposite side of GB6170GB6172, which is 21MM. In addition, the screw cap of the M22 has a 32mm opposite side of the DIN934 and GB52, which is 2mm smaller than the 34mm opposite side of the GB6170 and GB6172. ( GB6170 and GB6172 have exactly the same opposite side width except for their different thicknesses) The rest of the specifications can be used interchangeably without considering thickness.
The specifications of equal height screws are: M12, M16, M20, M22, M24, M27, M30; the specifications of torsion shear high strength bolts are: M16, M20, M22, M22, M24, M27, M30; the specifications of torsion shear high strength bolts are M16, M20, M22, M22, M24, M27, M30, all of which are classified by bolt diameter
m4 flat head hexagon socket bolt, 12 is the diameter, length according to own demand.