Common screw specifications

A: Metric screws

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 model

Metric screws directly indicate the screw type with the screw outer diameter. For example, M3 means the outer diameter of the screw is 3.00mm; M4 means the outer diameter of the screw is 4.00mm.

MetricThreadSizexPitch: (Note: Metric screws are on the back of 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 screws, directly indicate the length of the screw, 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. The exception is for flat head screws, where the total length of the screw includes the height of the head.

A-3: DriveCode/Head section grooves and features. The general specifications are as follows:

a.Slotted word b.Phillips cross c.Phil-Slot word/cross d.HexScoket: hexagon socket e.OneWay: one-way (guide: typical riveted parts)

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 processing. The general specifications are as follows:

a.Z: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 TappingType directly behind the product name. Ex: M3x6PPB, TappingType: M3 self-tapping screws, 6mm long, cross, round flat head, black plated. Generally, it is determined by product type or label, and then judged to be used as SheetMetal or plastic parts.

B: U.S. standard screws

a. Generally marked with a serial number, such as #2-56, #4-40, #6-32, #8-32, #10-24etc.

b. Or expressed in inch 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, general specifications are as follows:

a.#2-56:2番56牙b.#4-40:4番40牙c.#6-32:6番32牙d.#8-32:8番32牙e.# 10-24: 10 and 24 teeth are 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 screws

C-1: ThreadCode: All the marks will have the denominator as 8, and then directly call the number of the numerator.

Ex: 1/8x0.50PPB: 1 minute screw x0.50 length, PPB

Ex:5/16x0.50PPBu003d2.5/8x0.50-PPB: 2 points half screw x0.50 length, PPB

Ex: 5/32x0.50PPBu003d1.25/8x0.50-PPB: 1 minute, 2 centimeters and a half screw x 0.50 length, PPB

Ex: 1/4x0.50-PPBu003d2/8x0.50-PPB: 2 points screw x0.50 length, PPB

Note: Coarse teeth or fine teeth are sometimes 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 length, PPB.

C-2: LengthCode: It is marked in inches and must be multiplied by 25.40 to convert to mm

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