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UNI 1751 Standard Dimensions for Split lock washers

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This norm has been cancelled

Single coil spring washers - Normal series

The standard specifies the dimensions and the technical conditions of supply of the split spring washers to be used as a support element for screws, nuts and bolts of a class not higher than 5.8 with right-hand thread. The purpose of the application is to counter the loosening of a threaded connection due to settling of the support surfaces or thermal expansion.

For this purpose, the user must carefully evaluate the residual elastic force values ​​specified in table 1.

The anti-unscrewing effect is mainly generated by the action of the ends of the washer, with its particular chisel shape, on the relative supporting surfaces.

The use of split spring washers is not recommended in threaded connections subject to forces

perpendicular to its axis.

It should also be avoided for use in connections subject to particularly heavy use (for example in the event of frequent vibrations) or subject to specific safety regulations.

 

Dimensional Drawing and Technical Diagrams

287_LblsmD_uni-1751.jpg

Key Dimensions and Technical Parameters

Dimensions in mm - source UNI 1751
Publication date: 01/1988 - Supersedes 12/1970
Thread size
 d1
d2 max
b nom
 s1 nom r k h1
≈ weight in Kg x 1000 pcs (ρ=7,85 kg/dm3)
Type A Type B
max min min. max. min. max.
M 2 2.1 2.4 4.4 0.9 0.5 0.1 - - - 1 1.2
0.033
M 2.2 2.3 2.6 4.8 1 0.6 0.1 - - - 1.2 1.4
0.05
M 2.5 2.6 2.9 5.1 1 0.6 0.1 - - - 1.2 1.4
0.053
M 3 3.1 3.4 6.2 1.3 0.8 0.2 0.15 1.9 2.1 1.6 1.9
0.11
M 3.5 3.6 3.9 6.7 1.3 0.8 0.2 0.15 1.9 2.2 1.6 1.9
0.12
M 4
4.1
 4.4
7.6
1.5
 0.9 0.2 0.15 2.1 2.5
1.8
 2.1
0.18
M 5
5.1

5.4
9.2
1.8
 1.2 0.2 0.15 2.7 3.2
2.4
 2.8
0.36
M 6
6.1
 6.5
11.8
2.5
 1.6 0.3 0.2 3.6 4.2
3.2
 3.8
0.83
M 7 7.1 7.5 12.8 2.5 1.6 03 0.2 3.6 4.2 3.8 3.8
0.93
M 8
8.1
 8.6
14.8
3
 2 0.5 0.3 4.6 5.4
4
 4.7
1.6
M 10
10.2
 10.7
18.1
3.5
 2.2 0.5 0.3 5 5.9
4.4
 5.2
2.53
M 12
12.2
 12.7
21.1
4
 2.5 1 0.4 5.8 6.8
5
 5.9
3.82
M 14
14.2
 14.7
24.1
4.5
 3 1 0.4 6.8 8
6
 7.1
6.01
M 16
16.2
 17
27.4
5
 3.5 1 0.4 7.8 9.2
7
 8.3
8.91
M 18
18.2
 19
29.4
5
 3.5 1 0.4 7.8 9.2
7
 8.3
9.73
M 20
20.2
 21.2
33.6
6
 4 1 0.4 8.8 10.4
8
 9.4
15.2
M 22
22.5
 23.5
35.9
6
 4 1 0.4 8.8 10.4
8
 9.4
16.5
M 24
24.5
 25.5
40
7
 5 1.6 0.5 11 13
10
 11.8
26.2
M 27
27.5
 28.5
43
7
 5 1.6 0.5 11 13
10
 11.8
28.7
M 30
30.5
 31.7
48.2
8
 6 1.6 0.8 13.6 16.1
12
 14.2
44.3
M 33
33.5
 34.7
55.2
10
 6 1.6 0.8 13.6 16.1
12
 14.2
67.3
M 36
36.5
 37.7
58.2
10
 6 1.6 0.8 13.6 16.1
12
 14.2
71.7
M 39
39.5
 40.7
61.2
10
 6 1.6 0.8 13.6 16.1
12
 14.2
111
M 42
42.5
 43.7
68.2
12
 7 2 0.8 15.6 18.4
14
 16.5
117
M 45 45.5 46.7 71.2 12 7 2 0.8 15.6 18.4 16.5 16.5
123
M 48
49
 50.5
75
12
 7 2 0.8 15.6 18.4
14
 16.5
182
M 52
53
 54.5
83
14
 8 2 1 18 21.2
16
 18.9
193
M 56
57
 58.5
87
14
 8 2 1 18 21.2
16
 18.9
203
M 60
61
 62.5
91
14
 8 2 1 18 21.2
16
 18.9
218
M 64
65
 66.5
95
14
 8 2 1 18 21.2
16
 18.9
228
M 68
69
 70.5
99
14
 8 2 1 18 21.2
16
 18.9
240
M 72
73
 74.5
103
14
 8 2 1 18 21.2
16
 18.9
262
M 80
81
 82.5
111
14
 8 2 1 18 21.2
16
 18.9
290
M 90
91
 92.5
121
14
 8 2 1 18 21.2
16
 18.9
318
M 100
101
 102.5
131
14
 8 2 1 18 21.2
16
 18.9

Dimensions in mm-Split lock washers commercial type
Nominal size Thread size d b s D
≈ weight in Kg x 1000 pcs (ρ=7,85 kg/dm3)
3.2
M 3
3.2
 1.2 0.7 5.6 0.10
4.3
M 4
4.3
 1.4 0.8 7.1 0.172
5.3
M 5
5.3
 1.7 1.1 8.7 0.335
6.4
M 6
6.4
 2.3 1.4 11 0.68
7.4
M 7
7.4
 2.3 1.4 12 0.70
8.4
M 8
8.4
 2.8 1.8 14 1.27
10.5
M 10
10.5
 3.3 2 17.1 2
12.5
M 12
12.5
 3.7 2.2 19.9 3.13
15
M 14
15
 4.2 2.7 23.4 5.16
17
M 16
17
 4.7 3.2 26.4 7.38
19
M 18
19
 4.7 3.2 28.4 8.1
21
M 20
21
 5.6 3.6 32.2 11.9
23
M 22
23
 5.6 3.6 34.2 12.6
25
M 24
25
 6.6 4.6 38.2 20.2
28
M 27
28
 6.6 4.6 41.2 23.1

Dimensions in mm-Split lock washers heavy type
nominal size thread size d b s
D
 ≈ weight in Kg x 1000 pcs (ρ=7,85 kg/dm3)
3.2
M 3
3.2
 1.2 0.9 5.6 0.124
4.2
M 4
4.2
 1.2 0.9 6.6 0.202
5.2
M 5
5.2
 1.5 1.1 8.2 0.35
6.3
M 6
6.3
 2.5 1.8 11.3 0.96
7.3
M 7
7.3
 2.5 1.8 12.3 1.08
8.3
M 8
8.3
 3 2.2 14.3 1.7
10.4
M 10
10.4
 3.3 2.5 17 2.75
12.4
M 12
12.4
 4 3 20.4 4.6
14.5
M 14
14.5
 4.5 3.5 23.5 7.2
16.6
M 16
16.6
 5.2 4 27 10.6
18.6
M 18
18.6
 5.6 4.2 29.8 13.5
20.6
M 20
20.6
 6 4.5 32.6 16.3
22.7
M 22
22.7
 6.5 5 35.7 22
24.7
M 24
24.7
 7 5.5 38.7 28

Reproduced by permission of DIN Deutsches Institut für Normung e. V. The definitive version for the implementation of this standard is the edition bearing the most recent date of issue, obtainable from Beuth Verlag GmbH, Burggrafenstraße 6, 10787 Berlin, Germany.
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