1. Product name (standard)
Note: For screws without standard, which belong to non-standard parts, drawings need to be provided.
For example, DIN912, Chinese name: hexagon socket head screw, this is the name of the product.
However, the most accurate way, or need to address the standard, because GB70 is also such a product name; But there are many areas where the two standards are different in size.
The most influential standards in the world are: German standard (DIN), international standard (ISO), Chinese national standard (GB), American standard (ANSI), Japanese standard (JIS).
2.Specification
The general screw name is tooth pattern name diameter * screw length.
Tooth pattern address diameter, metric system commonly used: M2, M3, M4, M5, M6, M8, M10, M12;
American system commonly used are: 4#-40, 6#-32, 8#-32, 10#-24, 1/4-20, 5/16-18, 3/8-16, 1/2-13 and so on.
The length of the screw refers to the effective length of the embedded object. For EXAMPLE, COUNTERSUNK HEAD SCREWS ARE LOADED IN TOTAL LENGTH, HALF COUNTERSUNK HEAD SCREWS ARE LOADED IN HALF HEAD LENGTH, AND CYLINDRICAL HEAD SCREW LENGTH DOES NOT INCLUDE THE head size. Such as:
For specifications, the full name is best to add the tooth distance. For example, M4-0.7x8, the outer diameter of the 4-finger tooth is 4mm,0.7 refers to the distance between the two tooth peaks is 0.7mm, and the effective length of the 8-finger embedded object is 8mm.
For the sake of simplicity, we will leave the thick teeth as the standard teeth by default, because they are the most common; So I don't have to label it. This is the metric system, American products still need to mark the distance.
Here we focus on the specifications of American screws, such as 6#-32*3/8, 6# is the tooth diameter, close to 3.5mm; 32 is 32 teeth per inch of thread length (equivalent to the spacing of a metric screw); 3/8 is the length of the screw (exactly the same as the metric screw).
Here are two formulas to remember: 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 is to memorize the data. The number of teeth corresponding to each specification of screws should also be remembered: 2#-56, 4#-40, 6#-32, 8#-32, 10#-24, 1/4-20, 5/16-18, 3/8-16, 1/2-13 (American standard teeth).
Note: American UNC teeth are standard teeth and UNF teeth are fine teeth. We default thick teeth to standard teeth.
3.Material
Material according to the most common order: 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 made of ordinary grade products, such as 4.8 grade screws, ordinary grade nuts; C1015 general sling screw; C1018 general machine screw, of course, also used to do self-tapping nails; C1022 is generally used to do self-tapping nails; C1035 with 8.8 screws; C1045/10b21/40cr with 10.9 screws; 40Cr/SCM435 with 12.9 grade screws.
Stainless steel SS302/SS304/SS316 is the most common. Of course, now also popular a large number of SS201 products, even lower nickel content of products, we call not authentic stainless steel products; The appearance looks similar to stainless steel, but the anti-corrosion performance is much different.
4. Strength grade
Strength grade refers mainly to carbon steel fasteners.
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, 6, 8, 10, 12.
Generally, the screws below grade 8.8 are called ordinary screws, and the screws above grade 8.8 (including grade 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 anticorrosion performance, but also part of the color, so it is mainly for carbon steel products, generally need to go through surface treatment.
Common surface treatments are: black, galvanized, copper, nickel, chromium, silver, gold, dacro, hot dip zinc, etc.;
There are many kinds of galvanized, blue and white zinc, blue zinc, white zinc, yellow zinc, black zinc, green zinc, etc., but also divided into environmental protection and environmental protection, each type of plating and a variety of coating thickness, to meet the different salt spray test effect.
