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BS 4320 Standard Dimensions for Flat washers according to British norm

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Metal washers for general engineering purposes. Metric series

BS 4320 Relates to bright metal and black metal washers for use with ISO metric bolts, screws and nuts. The washers are basically divided into 3 categories of size: ''normal'', ''large'' and ''extra large'' diameter series and the bright washers are further divided by including a ''light range'' which have thicknesses approximately 60 per cent of the ''normal range'' thicknesses. The bright metal washers cover the range for bolts, M1 to M39, and the black metal washers cover the range M5 to M68. 

Dimensional Drawing and Technical Diagrams

345_4742.jpg

Key Dimensions and Technical Parameters

Dimensions in mm - source BS 4320
Publication date: 05/1968
Thread size
 Type
d min
d1 max
s nom
 ~Weight (7.85 Kg dm3) Kg/1000 Pcs
M 1 A 1.1 2.5 0.3
M 1.2 A 1.3 3 0.3
M 1.4 A 1.5 3 0.3
M 1.6 A 1.7 4 0.3
M 2 A 2.2 5 0.3
M 2.2 A 2.4 5 0.5
M 2.5 A 2.7 6.5 0.5
M 3
A
3.2
7
0.5
0.119
M 3.5 A 3.7 7 0.5
M 4
A
4.3
9
0.8
0.308
B
C
4.3
10
0.8
0.40
M 4.5 A 4.8 9 0.8
M 5
A
5.3
10
1
0.443
B
5.3
10
0.8
0.36
C
5.3
12.5
1
0.79
D
E
5.5
10
1
0.43
F
G
5.5
15
1.6
1.92
M 6
A
6.4
12.5
1.6
1.02
B
6.4
12.5
0.8
0.57
C
6.4
14
1.6
1.53
D
6.4
14
0.8
0.77
E
6.6
12.5
1.6
1.11
F
G
6.6
18
2
3.46
M 7 A 7.4 14 1.6
B 7.4 14 0.8
C
D
E 7.6 14 1.6
F 7.6 21 2
G
M 8
A
8.4
17
1.6
2.16
B
8.4
17
1
1.35
C
8.4
21
1.6
3.65
D
8.4
21
1
2.28
E
9
17
1.6
2.05
F
9
21
1.6
3.55
G
9
24
2
6.10
M 10
A
10.5
21
2
4.08
B
10.5
21
1.25
2.55
C
10.5
24
2
5.74
D
10.5
24
1.25
3.59
E
11
21
2
3.95
F
11
24
2
5.61
G
11
30
2.5
12.01
M 12
A
13
24
2.5
6.27
B
13
24
1.6
4.02
C
13
28
2.5
9.48
D
13
28
1.6
6.07
E
14
24
2.5
5.86
F
14
28
2.5
9.06
G
14
36
3
20.35
M 14 A 15 28

3
B 15 28 1.6
C 15 30 2.5
D 15 30 1.6
E 16 28 2.5
F 16 30 2.5
G 16 42 3
M 16
A
17
30
3
11.3
B
17
30
2
7.53
C
17
34
3
16.04
D
17
34
2
10.69
E
18
30
3
10.65
F
18
34
3
15.39
G
18
48
4
48.83
M 18 A 19 34 3
B 19 34 2
C 19 37 3
D 19 37 2
E 20 34 3
F 20 37 3
G 20 54 4
M 20
A
21
37
3
17.2
B
21
37
2
11.44
C
21
39
3
19.98
D
21
39
2
13.32
E
22
37
3
16.37
F
22
39
3
19.18
G
22
60
5
96.06
M 22 A 23 39 3
B 23 39 2
C 23 44 3
D 23 44 2
E 24 39 3
F 24 44 3
G 24 66 5
M 24
A
25
44
4
32.3
B
25
44
2.5
20.21
C
25
50
4
46.24
D
25
50
2.5
28.90
E
26.0
44
4
31.07
F
26
50
4
44.98
G
26
72
6
166.8
M 27 A 28 50 4
B 28 50 2.5
C 28 56 4
D 28 56 2.5
E 30 50 4
F 30 56 4
G 30 81 6
M 30
A
31
56
4
53.6
B
31
56
2.5
33.52
C
31
60
4
65.08
D
31
60
2.5
40.68
E
33
56
4
50.48
F
33
60
4
61.93
G
33
90
8
345.8
M 33 A 34 60 5
B 34 60 3
C 34 66 5
D 34 66 3
E 36 60 5
F 36 66 5
G 36 99 8
M 36
A
37
66
5
92.1
B
37
66
3
55.25
C
37
72
5
117.61
D
37
72
3
70.56
E
39
66
5
87.39
F
39
72
5
112.9
G
39
108
10
625.4
M 39 A 40 72 6
B 40 72 3
C 40 77 6
D 40 77 3
E 42 72 6
F 42 77 6
G 42 117 10
M 42
A
B
C
D
E
45
78
7
175.2
F
G
M 45 E 48 85 7
M 48
A
B
C
D
E
52
92
8
284.1
F
G
M 52 E 56 98 8
M 56
A
B
C
D
E
62
105
9
398.5
F
G
M 60 E 66 110 9
M 64
A
B
C
D
E
70
115
9
461.9
F
G
M 68 E 74 120 10

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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