ISO 3161 pdf download.Aerospace — UNJ threads — General requirements and limit dimensions
1 Scope
This International Standard specifies the general requirements and limit dimensions of inch series UNJ threads with controlled root radius for aerospace construction. It determines the basic triangular profile for this type of thread and gives a system for designating the diameter and number of threads per inch combinations. For all diameters 0,060 in (1 ,524 mm) to 6,000 in (1 52,4 mm), it offers in the form of tables the basic dimensions and tolerances for a selection of diameter and number of threads per inch combinations. It also provides the method of calculation for the dimensions and tolerances for any diameter and number of threads per inch combination not given in the tables, including threads with a diameter in excess of 6,000 in.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 1 5872:— 1 ? , Aerospace — UNJ threads — Gauging.
3 Term and definition
For the purposes of this International Standard, the following term and definition apply.
3.1 basic profile
in an axial plan, the theoretical profile corresponding to the basic dimensions
See Figure 1.
4 Basic profile
4.1 Symbols
See Figure 1 .
5.3 Number of threads perinch (n)
5.3.1 General Columns 3 to 9 (inclusive) of Table 3 give the numbers of threads per inch which are recommended to be associated with the diameters in columns 1 and 2. These columns of the numbers of threads per inch are divided into two groups: ? series with increasing (progressive) pitches: columns 3, 4 and 5; ? constant (uniform) pitch series: columns 6, 7, 8 and 9. 5.3.2 Series with increasing (progressive) pitches There are three series of increasing pitches. They are headed “Coarse pitch”, “Fine pitch” and “Extra fine pitch” in accordance with current practice. These terms indicate the relative pitches of the three series for each given thread diameter and do not imply a difference in quality between the series. 5.3.3 Constant (uniform) pitch series In addition to these three series of increasing pitches, Table 3 includes details of constant pitch series which have been selected from the range of 8 threads per inch to 20 threads per inch. Each of these series is limited to an appropriate range of diameters. 5.4 Threads outside selection The threads specified in 5.3.2 and 5.3.3 and indicated in Table 3 meet most requirements. If other diameter and number of threads per inch combinations or threads larger than 6,000 in in diameter are required, then these shall be calculated using the formulae in 6.3.2.
6 Tolerances
6.1 Length of thread engagement used for calculating the pitch diameter tolerances The length of thread engagement (L e ) (see Figure 2) used in this International Standard is equal to ? the basic major diameter for the series UNJC, UNJF and 8 UNJ. This is applicable for actual lengths of engagement between 1 ,0D and 1,5D; 9P for the series UNJEF, 1 2 UNJ, 1 6 UNJ, 20 UNJ and all UNJS. This is applicable for actual lengths of engagement between 5P and 1 5P. For applications with lengths of engagement not within the above limits, the tolerances on the pitch diameter shall be calculated according to the calculation formulae for T d2 and T D2 , using the design length of engagement as L e