CNC Knowledge: As a robot, what do you know about the thread code comparison table?

Identification by code and label of foreign wires

1. Inch thread (thread profile angle 55 degrees)

BSW—-Whitworth British Standard thread (coarse thread) BSF—-Whitworth British Standard thread (fine thread)

R—-External thread of conical pipe (old code ZG, KG) RC—-Internal thread of conical pipe (old code ZG, KG)

G—-Straight pipe thread (external threads are divided into A and B sides, taps are divided into G and GD)

2. American thread (60 degree thread profile)

UNC—Unified coarse thread (replaces NC) UNF—Unified fine thread (replaces NF)

UNEF—Uniform system of ultra-fine threads UN—Uniform system of constant pitch threads

UNS — NPT Unified Special Thread — American Standard Taper Pipe Thread

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

NPTF—Dry Seal Taper Pipe Thread NPSF—Dry Seal Fuel Straight Pipe Thread

NPSM—American standard mechanical fitting with straight pipe thread NPTR—American standard guide rod with tapered pipe thread

NPSL—Straight pipe thread for American standard pipe lock nut NPSH—Straight pipe thread for American standard pipe fitting

3.Other threads

SM—-Sewing machine thread PZ—-Conical gas bottle thread

51－201－Valve core thread

Annotation example

The 55° cylindrical pipe thread is an unthreaded sealed pipe thread and belongs to the Whitworth thread family. Metric and inch systems are widely used across countries. Pipe joints and pipe fittings for transporting liquids, gases and installing electrical wires. The national standard can be found in GB/T7307-2001. The complete mark includes thread characteristic code (G), thread size code, pitch diameter tolerance quality code (internal threads are omitted and unmarked, external thread codes are A and B) and the direction of rotation code:

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

The 3/8, 1/2 and 3/4 markings in the threads refer to the diameter of the thread size in inches. Insiders usually refer to thread size in “minutes”, one inch equals 8 stitches, 1/2 inch equals 4 stitches, and so on.

The 55° tapered pipe thread is a sealing pipe thread and belongs to the Whitworth thread family. This thread series is widely used around the world and is commonly used in the water and gas pipe industries. The taper is 1:16. The national standard can be found in GB/T7306-2000. The complete mark includes the thread characteristic code, thread size code and direction of rotation code:

The characteristic code for the sealed cylindrical internal thread in inches is RP; the characteristic code of the internal tapered sealed thread in inches is RC;

The characteristic code of the sealed tapered external thread in inches is R1 (used in conjunction with the sealed cylindrical internal thread in inches)

R2 (for use with sealed tapered internal threads in inches)

Sealed left-hand cylindrical internal thread, in inches, with 3/4 size code: RP3/4-LH

NPT is a 60 degree tapered pipe thread which belongs to American standard and has a taper of 1:16. It is used in North America and is also used in my country’s machine tool industry and the former Soviet Union. The national standard can be found in GB/T12716-1991. The complete mark includes the thread characteristic code, thread size code and direction of rotation code:

The characteristic code for general sealing tapered thread manufactured in the United States is NPT;

The characteristic code for the American-made general sealing cylindrical internal thread is NPSC;

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

2: nominal diameter is 2 inches; 12: 12 threads 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, that is, the nominal diameter is 19.05 mm.

Ordinary metric threads are divided into two types: coarse thread and fine thread. Ordinary coarse threads are represented by thread code (M) and nominal diameter, such as M10, M16, etc. ; Ordinary fine threads are represented by thread code (M) and nominal diameter × pitch, such as M10×1. , M20×1.5, etc. The complete thread mark is composed of the thread characteristic code, the tolerance zone code and the screw length code, such as M20×1.5-6g-S. M: thread code; 20: nominal diameter; 1.5: thread pitch; 6g: tolerance zone level; S: screw length (the average screw length is not marked).

The difference between metric threads and British threads: metric threads have an equilateral 60 degree profile, British threads have an isosceles 55 degree profile, and American 60 degree threads are represented by one pitch, and American threads and British are represented by threads; per inch. Expressed by the number of threads; metric threads are expressed in metric units and American and British threads are expressed in imperial units.

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

GB7306-1987 Commonly Used 55° Taper Pipe Thread Size Chart (PT, ZG, R)

Commonly used metric thread, standard pitch M (coarse thread)

UN dimensional tolerance (Carter standard) for commonly used American threads

GB/T12716-1991 Commonly Used 60 Degree Taper Pipe Thread Dimensions NPT