Description The parameters that need to be marked for fasteners are: product name (standard), specification, material, strength grade, surface treatment. Such as: DIN912, M4-0.7×8, SCM435, 12.9, black.

1, product name (standard) : Note: For screws without standards, which are non-standard parts, you need to provide drawings.

For example, DIN912, the Chinese name is called: hex cylindrical head screw, this is the name of the product.

But the most accurate approach, or need to call the standard, because GB70 is also such a name; But there are many areas where the two standards differ in size. The most influential standards in the world are: German standard (DIN), international standard (ISO), Chinese national standard (GB), American standard (ANSI), and Japanese standard (JIS).

2. Specifications, the general screw name is the tooth grain name diameter * screw length.

Dental diameter, metric commonly used are: M2, M3, M4, M5, M6, M8, M10, M12 and so on;

The US system is commonly used: 4#-40, 6#-32, 8#-32, 10#-24, 1/4-20, 5/16-18, 3/8-16, 1/2-13 and so on.

The screw length refers to the effective length of the embedded object. For example, countersunk screws are loaded with the total length, half countersunk screws are added to the length of the half head, and the length of the cylindrical head screws does not include the head size. For example: for specifications, the full name is best to add tooth spacing. For example, M4-0.7×8, 4 refers to the outer diameter of the tooth is 4mm,0.7 refers to the distance between the two tooth peaks is 0.7mm, and 8 refers to the effective length of the buried object is 8mm.

In order to simplify, do not write the tooth spacing, we will default to the coarse teeth as standard teeth, because the most common; So you don’t have to label it. This is only available in the metric system, and American products still need to mark the tooth spacing.

Here focus on the specifications of the American screw, such as 6#-32*3/8, 6# is the outer diameter of the tooth, close to 3.5mm; 32 is 32 teeth per inch of thread length (equivalent to the tooth spacing of metric screws); 3/8 is the length of the screw (specifically the same as the metric screw).

2 formulas to remember here: tooth diameter A#= (Ax0.013+0.06) x25.4 (mm), 1 inch =25.4mm.

Where 2#=2.2mm, 4#=2.9mm, 6#=3.5mm, 8#4.2mm, 10#=4.8mm are required to memorize the data. The number of teeth corresponding to the screws of each specification must also be memorized: 2#-56, 4#-40, 6#-32, 8#-32, 10#-24, 1/4-20, 5/16-18, 3/8-16, 1/2-13 (US standard teeth).

Note: American UNC teeth are standard teeth, UNF teeth are fine teeth. We default rough teeth to standard teeth.

3, material: material according to the most common sequence: carbon steel, stainless steel, stainless iron, copper, aluminum and so on.

Carbon steel is divided into low carbon steel (such as C1008 C1010 / C1015 / C1018 / C1022), medium carbon steel (such as C1035), high carbon steel (C1045 / C1050), alloy steel (SCM435/10 b21/40 cr). General C1008 material is to play ordinary grade products, such as 4.8 grade screws, ordinary grade nuts; C1015 generally play ring screws; C1018 generally do machine screws, of course, there are also used to do self-tapping nails; C1022 is generally used to make self-tapping nails; C1035 play 8.8 screws; C1045/10B21/40Cr make 10.9 screws; 40Cr/SCM435 with 12.9 level screws.

For stainless steel, SS302/SS304/SS316 are the most common. Of course, a large number of SS201 products are now popular, and even products with lower nickel content, which we call non-authentic stainless steel products; The appearance looks similar to stainless steel, but the corrosion resistance is much different.

4, strength grade: Strength grade mainly refers to carbon steel fasteners.

The common strength grades of carbon steel screws are: 4.8, 5.8, 6.8, 8.8, 10.9, 12.9. The corresponding nuts are: 4 grades, 6 grades, 8 grades, 10 grades, 12 grades.

Generally, the screws below 8.8 are called ordinary screws, and the screws above 8.8 (including 8.8) are high-strength screws. The difference is that high strength screws need to undergo tempering heat treatment.

5, surface treatment: surface treatment is mainly to increase the corrosion resistance, but also part of the color, so mainly for carbon steel products, generally need to go through surface treatment.

Common surface treatments are: blackening, zinc plating, copper plating, nickel plating, chromium plating, silver plating, gold plating, dacromet, hot dip zinc, etc.

There are many types of galvanizing, including blue and white zinc, blue zinc, white zinc, yellow zinc, black zinc, green zinc, etc., and it is also divided into environmental protection and not environmental protection, and each plating type has a variety of coating thickness to meet different salt spray test effects.