What are the specifications of the screws?

Screw specification model
Example: 4 X 10 PW A H C (+)
①　②　③　④　⑤　⑥　⑦
① Screw diameter　② Screw length　③ Screw head type
B: Spherical cylindrical head; C: Cylindrical head; F(K): Countersunk head; H: Hexagon head; HW: Hexagon head with washer; O: Semi countersunk head; P: Flat head; R: Half head; PW : Flat head with washer; T: big flat head; V: mushroom head;
④ Screw thread type
A: Self-tapping pointed tail (Japanese standard No. 1), sparse AB: Self-tapping pointed tail (Japanese standard No. 4) dense; B: Self-tapping flat tail (Japanese standard second) sparse; C: Self-tapping flat tail (Japanese Standard 3) dense; P: double thread HL: high and low thread U: pineapple tooth pattern; T: self-tapping flat tail cut foot AT: self-tapping threaded tip cut foot M: mechanical teeth; BTT: B triangle teeth CCT : C-shaped triangular teeth PTT: P-shaped triangular teeth STT: S-shaped triangular teeth
⑤ Heat treatment H: with heat treatment N: without heat treatment
⑥ Surface treatment
Zn: White zinc C: Color zinc B: Blue zinc F: Black zinc O: Black oxide Ni: Nickel Cu: Bronze Br: Red copper P: Phosphating
⑦ Remarks
(+): Cross slot (-): One slot (T): Chrysanthemum slot (H): Hexagon socket (PZ): Pozi slot
(+-): +-slot (Y): Y-slot (H): H-slot (L): anti-retracting tooth (WIS): single movable spring washer
(WIF): Single movable flat washer (WIT): Single movable external tooth washer (W2SF): Double movable flat washer
(W=6mm): the outer diameter of the washer is equal to 6mm (SUS): stainless steel (Cu): brass (Br): copper (8.8): 8.8 screws (10.9): 10.9 screws (12.9): 12.9 screws ( R): Other notes
① Nominal thread outer diameter (thread specifications): There are two types: metric and inch.
Metric thread → Common specifications are 2; 2.3; 2.5; 2.6; 2.9; 3; 3.1; 3.5; 4; 4.2; 4.5; 4.8;
5; 6; 8; 10; 12; 14; 16; 20. The unit is mm (millimeters).
Inch thread → common specifications are 2#;4#;6#;8#;10#;12#;1/4;7/32;5/16;3/8;1/2;9/16; 3/ 4. Unit in (English
Inch).
② Tooth number/tooth distance:
Definition of tooth number → The number of tooth patterns contained in one inch (25.4mm) length.
Tooth pitch definition → The value of the distance between two adjacent threads.
Conversion of tooth number and tooth pitch → tooth pitch = 1 inch/tooth number
③Nominal length: There are two types: metric system and imperial system.
Metric nominal length → common values ​​are 5, 6, 6.5, 7, 8, 9, 9.5, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20,
21, 25, 28, 30, 31, 32, 35, 40, 42, 45, 50, 55, 60, 65, 70, 75, 80, 85,
90, 95, 100, 110, 120. The unit is mm (millimeters).
Nominal length in inch system → Common values ​​are 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 1, 2, 3. Unit: in (inch).
④Head type: Letters are used to indicate the type of head type, please refer to the previous classification of common screw head types.
⑤Tooth type/tail type: Use letters to indicate the type of tooth type/tail type, please refer to the previous "Commonly used screw type/tail type classification".
⑥Groove type: Refer to the "Classification of Groove Types of Our Commonly Used Screws" above, cross-recessed or non-slotted (such as punched hexagon head screws), no need to mark here, other groove types
Need to use text description.
⑦Special label: In general, there is no need to label. When expressing its characteristics, use text at this position to describe.
Example: The description of the screw specification name is "4-0.7x70PM±tooth length 35", which means "4" is the nominal diameter of the screw thread, and "0.7" is the tooth
Pitch, 70" is the nominal length of the screw, "P" means that its head type is pan head, "M" means its thread/tail type is machine thread type, "±"
It means that the groove type is "± groove" or "plus and minus groove". "Tooth length 35" is a special mark, especially indicating the length of the screw thread.

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