Screw specification definition and understanding

1. Thread type: 　

A: Triangular Thread: Combination/Locking 　　B: Triangular Thread for Pipe: Combination/Locking 　　C: Trapezoidal Thread: Power Transmission 　　D: Square Thread: Power Transmission 　　

2. Common types of screws: 　　

A: MachineScrew: Mechanical screw 　　B: TappingScrew: Self-tapping screw 　　B-1: SheetMetalTappingScrew.　　B-2: PlasticTappingScrew.　　C: WoodenScrew. Woodworking screw 　　D: DrywallScrew. Cement wall screws 　　

Three, common screw material: 　　

a.LowCarbonSteel. Low carbon steel 　　b.SS-304: StainlessSteel304 　　c.SS-302: StainlessSteel302 has better structural toughness 　　d.Aluminum5052: Aluminum alloy 5052 　　e.Brass: Brass 　　f.Bronze: Bronze Cop: UNSC11000

4. Common screw specifications and markings: 　　

A: Metric screw 　　B: American standard screw 　　C: Inch screw 　　A: Metric machine screw: Metric Ex: M3x6PPB: M3 machine screw, 6mm long, cross, round flat head, black plated.　　FinishCode: Appearance processing specifications 　　HeadCode: Head shape 　　ThreadCode 　　Screw model DriveCode: Head section groove, characteristic model 　　LengthCode: Screw length (mm) 　　A-1: ThreadCode: Screw external diameter 　　 directly mark the screw model with the screw metric.　　 Such as M3, the screw outer diameter is 3. 00mm; M4, the screw outer diameter is 4. 00mm. (Guide: Introduction to the basic knowledge of cold heading and cold extrusion)

　　MetricThreadSizexPitch: 　　Note: The metric screw is behind the screw model, sometimes the screw pitch is indicated.　　 such as M3x0.5, M4x0.70, M5x0.8, M6x1.　　 But because of the standard, it is usually not mentioned.　　A-2: LengthCode. Screw length 　　 metric screw, directly indicate the screw length, the unit is mm.　　 The total length of the screw is indicated, only the length below the head is calculated, without the height of the head.　　With the exception of flat head screws, the total length of the screw is indicated including the height of the head.　　A-3: DriveCode/head section groove, feature. The common specifications of 　　 are as follows: 　　a.Slotted word 　　b.Phillips cross 　　c.Phil-Slot one word/cross 　　d.HexScoket: inner hexagon 　　e.OneWay: one-way code/head type A-4. Common specifications are as follows: 　　a.Flat: flat head b.Oval: salad head c.Round: round head d.Pan: round flat head e.Truss: big round flat head f.Hex: hexagon head A-5: FinishCode/Appearance treatment Commonly used specifications are as follows: 　　 aZ: Zine-Plated: zinc-plated b.Ni: Ni-Plated: nickel-plated c.Tin-Plated: tin-plated d.ZinePlated/GreenIridite: zinc-plated green film treatment.　　E.RadiantPlated: Multicolored plating 　　f.Passivate: Antioxidant treatment.　　G. AlodialFinish: No appearance treatment.　　Metric self-tapping screws: Mark the TappingType directly after the product name.　　Ex: M3x6PPB, TappingType: 　　 M3 self-tapping screw, 6mm long, cross, round flat head, black plated.　　 Generally use product type or label, and then judged as SheetMetal or plastic parts.　　B: American standard screws.　　A. Generally marked with a serial number, such as #2-56, #4-40, #6-32, #8-32, #10-24 etc.　　B. Or expressed in English outer diameter.　　 Such as 0: 0.86-56, 0.112-40, 0.138-32, 0.164-32, 0.190-24 etc. Ex: 6328PPB: 　　 FinishCode: Appearance processing specifications HeadCode: Head shape DriveCode: Head section groove, characteristic model LengthCode: Screw length ThreadCode: Screw model B-1: ThreadCode: Screw model The general common specifications are as follows: 　　a.#2- 56: 2 Fan 56 Teeth b. #4-40: 4 Fan 40 Te c. #6-32: 6 Fan 32 Te d. #8-32: 8 Fan 32 Te e. #10-24: 10 Fan 24 Te ** Tooth is the number of teeth per inch. ＊＊＊ 　　B-2: LengthCode: Screw length 　　 US standard screw length must be converted to the metric mm size.　　 Conversion formula: x25.40u003dMetric length mm 　　B-3, B-4, B-5: The marking method is the same as the metric system.　　C: Inch screw: 　　C-1: ThreadCode: 　　 In all indications, set the denominator to 8, and then directly call the number of the numerator. Ex: 1/8x0.50PPB: 1 minute screw x0.50' long, PPB 　　 Ex: 5/16x0.50PPBu003d2.5/8x0.50-PPB: 2 half screw x0.50' long, PPB 　　 Ex: 5 /32x0.50PPBu003d1.25/8x0.50-PPB: 1 minute, 2 centimeters and a half screw x0.50' long, PPB 　　Ex: 1/4x0.50-PPBu003d2/8x0.50-PPB: 2-point screw x0. 50' long, PPB 　　 Note: Sometimes coarse or fine teeth are indicated.　　UNF: Fine teeth: more commonly used in the electronics industry.　　UNC: Coarse teeth: Heavy mechanical structures are more commonly used.　　Ex: 3/8x0.50, UNFPPB: 3-point fine screw 0.50' long, PPB. 　　C-2: LengthCode: 　　 is marked in inches and must be multiplied by 25.40 to convert to mm

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