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ISO 965-1 Aerospace Standard MJ Threads

The MJ screw thread is intended for aerospace metric threaded parts and for other highly stressed applications requiring high temperature or high fatigue strength, or for “no allowance” applications. The MJ profile thread is a hard metric version similar to the UNJ inch standards, ANSI/ASME B1.15 and MIL-S-8879. The MJ profile thread has a 0.15011P to 0.180424P controlled root radius in the external thread and the internal thread minor diameter truncated to accommodate the external thread maximum root radius. First issued in 1978, the American National Standard ANSI/ASME B1.21M-1997 establishes the basic triangular profile for the MJ form of thread; gives a system of designations; lists the standard series of diameter-pitch combinations for diameters from 1.6 to 200 mm; and specifies limiting dimensions and tolerances. Changes included in the 1997 revision are the addition of tolerance class 4G6G and 4G5G/4g6g comparable to ANSI/ASME B1.15 (UNJ thread); the addition of tolerance class 6H/6g comparable to ANSI/ASME B1.13M; and changes in the rounding proceedure as set forth in ANSI/ASME B1.30M.

4h6h Threads 4H6H;4H5H Threads

Limit dimensions for 4h6h threads for bolts

MJ Threads

Thread designation Major diameter d Pitch diameter d2 Minor diameter d3
th th2 th3
max. min. (6h) a max. min. (4h) a max. min.
MJ1,6 x 0,35-4h6h 1600 1515 85 1373 1333 0,04 1196 1135 61
MJ2 x 0,4-4h6h 2000 1905 95 1740 1698 42 1538 1472 66
MJ2,5 x 0,45-4h6h 2,5 2,4 0,1 2208 2163 45 1980 1908 72
MJ3 x 0,5-4h6h 3000 2894 106 2675 2627 48 2423 2345 78
MJ3,5 x 0,6-4h6h 3500 3375 125 3110 3057 53 2807 2718 89
MJ4 x 0,7-4h6h 4,00 3,86 0,14 3545 3489 56 3192 3094 98
MJ5 x 0,8-4h6h 5,00 4,85 0,15 4,48 4,42 0,06 4076 3968 108
MJ6 x 1-4h6h 6,00 5,82 0,18 5350 5279 71 4845 4713 132
MJ7 x 1-4h6h 7,00 6,82 0,18 6350 6279 71 5845 5713 132
MJ8 x 1-4h6h 8,00 7,82 0,18 7350 7279 71 6845 6713 132
MJ10 x 1,25-4h6h 10000 9788 212 9188 9113 75 8557 8406 151
MJ12 x 1,25-4h6h 12000 11788 212 11188 11103 85 10557 10396 161
MJ14 x 1,5-4h6h 14000 13764 236 13026 12936 0,09 12268 12087 181
MJ16 x 1,5-4h6h 16000 15764 236 15026 14936 0,09 14268 14087 181
MJ18 x 1,5-4h6h 18000 17764 236 17026 16936 0,09 16268 16087 181
MJ20 x 1,5-4h6h 20000 19764 236 19026 18936 0,09 18268 18087 181
MJ22 x 1,5-4h6h 22000 21764 236 21026 20936 0,09 20268 20087 181
MJ24 x 2-4h6h 24,00 23,72 0,28 22701 22595 106 21691 21464 227
MJ27 x 2-4h6h 27,00 26,72 0,28 25701 25595 106 24691 24464 227
MJ30 x 2-4h6h 30,00 29,72 0,28 28701 28595 106 27691 27464 227
MJ33 x 2-4h6h 33,00 32,72 0,28 31701 31595 106 30691 30464 227
MJ36 x 2-4h6h 36,00 35,72 0,28 34701 34595 106 33691 33464 227
MJ39 x 2-4h6h 39,00 38,72 0,28 37701 37595 106 36691 36464 227
  • A) In accordance with ISO 965-1

Limit dimensions of 4H6H threads for nuts of diameter MJ1,6 to MJ5 and limit dimensions of 4H5H threads for nuts of diameter MJ6 to MJ39

Limit dimensions of 4H6H threads for nuts of diameter MJ1,6 to MJ5 and limit dimensions of 4H5H threads for nuts of diameter MJ6 to MJ39

Thread designation Major D3 a Pitch diameter D2 Minor diameter D1
th2 th1
max. max. min. (4H) b max. min. (6H) b (5H) b
MJ1,6 x 0,35-4H6H 1704 1426 1373 53 1359 1259 0,1
MJ2 x 0,4-4H6H 2114 1796 1740 56 1722 1610 112
MJ2,5 x 0,45-4H6H 2625 2268 2208 0,06 2187 2062 125
MJ3 x 0,5-4H6H 3135 2738 2675 63 2653 2513 0,14
MJ3,5 x 0,6-4H6H 3658 3181 3110 71 3075 2915 0,16
MJ4 x 0,7-4H6H 4176 3620 3545 75 3498 3318 0,18
MJ5 x 0,8-4H6H 5195 4,56 4,48 0,08 4421 4221 0,2
MJ6 x 1-4H5H 6239 5445 5350 95 5216 5026 0,19
MJ7 x 1-4H5H 7239 6445 6350 95 6216 6026 0,19
MJ8 x 1-4H5H 8239 7445 7350 95 7216 7026 0,19
MJ10 x 1,25-4H5H 10,28 9288 9188 0,1 8994 8782 212
MJ12 x 1,25-4H5H 12292 11300 11188 112 10994 10782 212
MJ14 x 1,5-4H5H 14335 13144 13026 118 12775 12539 236
MJ16 x 1,5-4H5H 16335 15144 15026 118 14775 14539 236
MJ18 x 1,5-4H5H 18335 17144 17026 118 16775 16539 236
MJ20 x 1,5-4H5H 20335 19144 19026 118 18775 18539 236
MJ22 x 1,5-4H5H 22335 21144 21026 118 20775 20539 236
MJ24 x 2-4H5H 24429 22841 22701 0,14 22351 22051 0,3
MJ27 x 2-4H5H 27429 25841 25701 0,14 25351 25051 0,3
MJ30 x 2-4H5H 30429 28841 28701 0,14 28351 28051 0,3
MJ33 x 2-4H5H 33429 31841 31701 0,14 31351 31051 0,3
MJ36 x 2-4H5H 36429 34841 34701 0,14 34351 34051 0,3
MJ39 x 2-4H5H 39429 37841 37701 0,14 37351 37051 0,3
  • A) D3 min. is not specified. However, it shall be greater than D
  • B) In accordance with ISO 965-1