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 heads; C: Cylindrical heads; F(K): Countersunk heads; H: Hexagonal heads; HW: Hexagonal head band washers; O: Semi-sinking heads; P: Pingyuan heads; R: Half-element heads; PW : Pingyuan headband washer; T: big flat head; V: mushroom head;
4 screw teeth type
A: Self tapping tail (day 1st) Dr. AB: Self tapping tail (day 4) Secret; B: Self tapping tail (day 2) sparse; C: Self tapping tail (day Mark 3rd) dense; P: double thread HL: high and low teeth U: pineapple teeth pattern; T: self-tapping flat tail cut foot AT: self-tapping tip cut foot M: mechanical teeth; BTT: B triangular teeth CCT : Type C Triangular Teeth PTT: P Type Triangular Teeth STT: S Type Triangular Teeth
5 heat treatment H: heat treatment N: no 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 (-): Slot (T): Chrysanthemum slot (H): Inside hexagon (PZ): Square slot
(+-): +-slot (Y): Y-slot (H): H-slot (L): Retaining recessed teeth (WIS): Single spring washer
(WIF): Single Action Flat Washer (WIT): Single Action External Washer (W2SF): Double Action Flat Washer
(W=6mm): Washer outside diameter equal to 6mm (SUS): Stainless steel (Cu): Brass (Br): Red copper (8.8): Class 8.8 screws (10.9): Class 10.9 screws (12.9): Class 12.9 screws ( R): other notes
1 Nominal thread diameter (thread size): metric and imperial.
Metric threads → 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 (mm).
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 Number of teeth/distance:
Tooth Number Definition → The number of teeth in one inch (25.4 mm) length.
Tooth definition → The distance between two adjacent threads.
Tooth number, pitch conversion → Tooth pitch = 1 inch / number of teeth
3 nominal length: Two kinds of metric and imperial.
Metric nominal length → Commonly used 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 (mm).
British system nominal length → commonly used values are 1/4, 5/16, 3/8, 7/16, 1/2, 5/8, 3/4, 1, 2, 3. Unit :in (inches).
4 head type: Use the letters to indicate the type of head type, see the common screw head type above.
5 Tooth/Caudal Types: Letters are used to indicate the type of tooth/tail shape. See above for the “common screw shape/tail shape classification”.
6-slot type: Refer to “Classification of Commonly Used Screw Grooves” in the previous section. Cross-slot or non-slot (such as hex-head screws) are not required to be marked here. Other types of slots need to be written.
7Special labeling: In general, no labeling is required. When characters are expressed, they are described in text at this position.
Example: The screw specification name is described as "4-0.7x70PM ± tooth length 35", which means "4" is the nominal diameter of the screw thread and "0.7" is the tooth
Distance, 70” is the nominal length of the screw, “P” indicates that the head is a pan head, “M” indicates that the tooth/tail is a machine tooth, “±”
It means that the slot type is “±slot” or “slot plus slot”. "Tooth length 35" is a special labeling, which specifically states the length of the screw's teeth.
The above is a description of what the screw specification standards are and what the screw specification types are. I believe we should have more understanding after reading it. The content is for your reference only and we hope to be helpful to everyone.