CNC Machining and CNC Machine Tools

As a CNC person, how much do you know about the thread code comparison table

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Code and label identification of foreign threads. China Manufacturer of where to buy metal near me

  1. Inch thread (thread profile angle 55 degrees)

BSW—-British Standard Wyeth Thread (Coarse Pitch) BSF—-British Standard Wyeth Thread (Fine Pitch)

R—-cone pipe external thread (old code ZG, KG) RC—-cone pipe internal thread (old code ZG, KG)

G—-Straight pipe thread (external thread is divided into A and B two-face level, and tap is divided into G, G-D)

  1. American thread (thread profile 60 degrees)

UNC—Unified coarse thread (instead of NC) UNF—Unified fine thread (instead of NF)

UNEF—Unified superfine thread UN—Unified constant pitch thread

UNS—Unified special thread NPT—American standard taper pipe thread

NPSC—Straight pipe thread for American standard pipe joints NGT—Taper thread for gas cylinders

NPTF—Dry sealed taper pipe thread NPSF—Dry sealed fuel straight pipe thread

NPSM—U.S. standard straight pipe thread for mechanical connection NPTR—U.S. standard guide rod with tapered pipe thread

NPSL—Straight pipe thread for American standard pipe lock nut NPSH—Straight pipe thread for American standard hose connection. China Manufacturer of where to buy metal near me

  1. Other threads

SM—-Sewing machine thread PZ—-Taper thread for gas cylinder

51-201-Valve core thread

Annotation example

The 55° cylindrical pipe thread is a non-thread sealed pipe thread and belongs to the Wyeth thread family. Both metric and inch systems are widely adopted in countries. It is used to connect pipe joints and pipes for conveying liquids, gases, and installing wires. National standards can be found in GB/T7307-2001. The complete mark is composed of thread feature code (G), thread size code, pitch diameter tolerance class code (internal thread is omitted without marking, and external thread code is A and B) and rotation direction code:

Grade A, right-handed, non-sealed cylindrical external thread with size code 3/4 is marked as: G3/4A

The 3/8, 1/2, 3/4 marks in the thread refer to the diameter of the thread size, and the unit is inches. Insiders usually use “minutes” to refer to the thread size, one inch equals 8 points, 1/2 inch equals 4 points, and so on

The 55° tapered pipe thread is a threaded sealing pipe thread and belongs to the Wyeth thread family. This series of threads are widely used in the world, often used in water and gas pipe industries. The taper is 1:16. National standards can be found in GB/T7306-2000. The complete mark is composed of thread feature code, thread size code and rotation direction code:

The feature code of inch sealed cylindrical internal thread is RP; the feature code of inch sealed cone internal thread is RC;

The characteristic code of inch-sealed tapered external thread is R1 (used with inch-sealed cylindrical internal thread)

R2 (used in conjunction with inch sealed cone internal thread)

Left-handed, inch sealed cylindrical internal thread with size code 3/4: RP3/4-LH. China Manufacturer of where to buy metal near me

NPT is a 60-degree tapered pipe thread that belongs to the American standard, and the taper is 1:16. Used in North America, it is also used in my country’s machine tool industry and the former Soviet Union. National standards can be found in GB/T12716-1991. The complete mark is composed of thread feature code, thread size code and rotation direction code:

The characteristic code of American-made general sealed tapered pipe thread is NPT;

The characteristic code of American-made general sealed cylindrical internal thread is NPSC;

The standard series of American threads include three series of coarse thread (UNC), fine thread (UNF) and ultra-fine thread (UNEF), plus a fixed pitch series (UN). The complete mark consists of nominal diameter, number of teeth per inch, series code, accuracy grade and inspection system code: 2-12UN-2A(23) 3/4-18UNS

2: Nominal diameter is 2 inches; 12: 12 teeth per inch; UN: thread series code; 2A: tolerance zone code; (23) inspection system code. Calculation method: 1 inch = 25.4 mm. Converted to metric units, such as 3/4×25.4=19.05, the nominal diameter is 19.05 mm.

Metric ordinary threads are divided into two types: coarse thread and fine thread. Coarse common thread is expressed by thread code (M) and nominal diameter, such as M10, M16, etc.; fine common thread is expressed by thread code (M) and nominal diameter × pitch, such as M10×1, M20×1.5, etc. The complete thread mark is composed of thread feature code, tolerance zone code and screw length code, such as M20×1.5-6g-S. M: thread code; 20: nominal diameter; 1.5: thread lead; 6g: tolerance zone grade; S: screw length (medium screw length is not marked).

The difference between metric thread and inch thread: metric thread is 60 degree equilateral thread, inch thread is 55 degree isosceles thread, American thread is 60 degrees; metric thread is expressed by pitch, and American and imperial thread uses thread per inch It is expressed by the number of teeth; metric threads use metric units, and American and British threads use imperial units.

GB7307-1987 Commonly used 55° cylindrical pipe thread size table (PF, G)

China Manufacturer of where to buy metal near me
China Manufacturer of where to buy metal near me

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