05-29

Screw classification

The main categories include ordinary screws, machine screws, self tapping screws, and expansion screws. Cap screw used to be limited to full tooth fasteners. Hexagonal head screw Hex cap screw and large hexagonal bolt Hex bolt, as the name suggests, are externally threaded fasteners with a hexagonal head, designed to be turned with a wrench. According to the ASME B18.2.1 standard, hex cap screws have a smaller tolerance for head height and stem length compared to regular large hex bolts. Therefore, ASME B18.2.1 hex screws are suitable for installation in all areas where hex bolts can be used, as well as in areas where large hex bolts are too large to be used. Socket cap screw, also known as socket head screw or socket head screw, is a screw with a hexagonal inner hole on the head that can only be tightened or loosened after inserting a hex key (Allen wrench or Allen key) into the inner hole. The most commonly used hexagon socket head screws are cylindrical head screws with a head diameter of approximately 1.5 times the main diameter of the thread (1960 series). Other head types include bottom head cap screws for aesthetic appearance and counter head cap screws suitable for tapered screw holes. The counterbore design allows the screw head to rotate even without being exposed to the surface of the fixed object, so it is often used in areas with small surfaces and inconvenient for traditional wrench use. Machine screws generally have a diameter less than¼ Inch screws (4 #~12 #) are usually full teeth and rotated by a screwdriver, such as slotted, cross or hexagonal. Wood screws, machine screws; But according to different purposes, it can be divided into many categories; Within the machine screw category, it can be divided into longitudinal fastening screws and transverse expansion screws; According to the thread, it can also be divided into: A: Triangle thread (60 degrees): engagement/locking/expansion B: Pipe triangular thread (55 degrees): engagement/locking 3) C: Trapezoidal thread (30 or 29 degrees): power transmission D: Square thread (90 degrees): power transmission Stainless steel screws Screws And Shafts For Motorcycle Or Bicycle Screws And Shafts For Sewing Machine Socket Set Screws Stainless Steel Coat Thread Screws Stainless Steel High Low Thread Screws Stainless steel mechanical screw Stainless S

05-29

Material knowledge of screws

At present, there are three main materials of standard parts in the market: carbon steel, stainless steel, and copper. One carbon steel. We distinguish low carbon steel, medium carbon steel, high carbon steel, and alloy steel based on the carbon content in carbon steel materials. Low carbon steel with C% ≤ 0.25% is commonly referred to as A3 steel in China. Basically referred to as 1008101510181022 in foreign countries. Mainly used for products without hardness requirements such as grade 4.8 bolts, grade 4 nuts, and small screws. (Note: The drilling tail nail is mainly made of 1022 material.) 2% carbon steel 0.25% 3. High carbon steel C%>0.45%. Basically not used in the market 4 alloy steel: Adding alloy elements to plain carbon steel increases some special properties of the steel, such as 35, 40 chromium molybdenum, SCM435, and 10B38. Fangsheng screws mainly use SCM435 chromium molybdenum alloy steel, with main components including C, Si, Mn, P, S, Cr, and Mo. Two stainless steels. Performance level: 45, 50, 60, 70, 80 1. The main components of austenite (18% Cr, 8% Ni) have good heat resistance, corrosion resistance, and weldability. A1, A2, A4 2 martensite and 13% Cr have poor corrosion resistance, high strength and good wear resistance. C1, C2, C4 ferritic stainless steel. 18% Cr has better upsetting performance and corrosion resistance than martensite. The main imported materials in the market are from Japan. Mainly divided into SUS302, SUS304, and SUS316 by level. Three copper. The commonly used material is brass... zinc copper alloy. H62, H65, and H68 copper are mainly used as standard parts in the market.

05-29

Industrial Application of Screws

The main purpose is to make industrial products fixed as a whole. During use, it is common to encounter precision issues such as the inability to close between teeth, excessive force locking causing the screw head to break, or poor tooth pattern locking that fails to meet the usage conditions. Screws are "quantity products", not handmade artworks. In mass production, they aim to achieve high-precision, stable quality, and affordable supply to consumers. The accuracy of screws is usually level 6g (level 2, American specification "IFI" is 2A teeth), and rough screws used in construction projects are level 8g (level 3, "IFI" is 1A teeth). Common screw types A: Machine Screw: B: Tapping Screw: Self tapping screw (available in two types: metal and plastic) B-1: Sheet Metal Tapping Screw (Iron plate thread self tapping screw) B-2: Plastic Tapping Screw (For plastic, self tapping screws) C: Wooden Screw: Wooden Screw D: Drywall Screw: Cement wall screw E: Self Drilling Screws (stainless steel drilling screws, composite drilling screws) F: Expansion screw, also known as four piece gecko. The grades of expansion bolts are divided into: 45, 50, 60, 70, and 80. The material of expansion screws is mainly divided into austenitic A1, A2, and A4, 1. Stainless steel plate, metal steel plate, galvanized steel plate, engineering installation. 2. Metal curtain walls, metal light compartments, and other indoor and outdoor installations 3. Generally, angle steel, channel steel, iron plate are installed in combination with other metal materials. 4. Assembly works of car body, container, shipbuilding, refrigeration, screw machine equipment, etc. Features: 1. Drilling and tapping teeth, locking completed in one go, with strong adhesion. 2. Save construction time and improve work efficiency. E-1: Stainless Steel SELF DRILLING SCREWS E-2: Bi Metal Self Drilling Screws Common materials a. Low Carbon Steel: Carbon steel is divided into low carbon steel, medium carbon steel, high carbon steel, and alloy steel. b. SS-304: Stainless Steel 304, 316 are all stainless steel or similar c. SS-302: Stainless Steel 302: Good structural toughness d. Aluminum 5052: Aluminum alloy 5052 d. Brass: Brass e. Bronze f. UNS C11000 Copper: antimony copper