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Home / Products / Screws / Hexagon Socket Screws / DIN 7991:1986 Countersunk Head Hex Socket Screw

DIN 7991:1986 Countersunk Head Hex Socket Screw

DIN 7991:1986 Countersunk Head Hex Socket Screw combines a hex socket drive with a countersunk head, making it suitable for fastening points that require reliable clamping, removable maintenance, and standardized assembly. The DIN standard background helps keep dimensional requirements clear across drawings, purchasing, and quality inspection, supporting smooth alignment between engineering drawings, purchasing lists, and quality inspection.

From an assembly perspective, the internal hex socket provides deeper tool engagement, enabling higher assembly torque in compact spaces while reducing external head interference. At the same time, the tapered head seats into a prepared countersink, allowing the screw to sit flush or nearly flush with the surface, so the screw can provide stable fastening performance across different sheet thicknesses, appearance requirements, and space limitations.

It works well on flat surfaces, rails, covers, module housings, and areas where snagging or interference should be avoided. For batch assembly, the product can be tailored around workstation tools, tightening torque, visual grade, and packaging method to reduce sorting cost and improve assembly consistency.

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Dimensions unit: mm

Thread size d

M3

M4

M5

M6

M8

M10

M12

(M14)

M16

(M18)

M20

(M22)

M24

P

Pitch

0.5

0.7

0.8

1

1.25

1.5

1.75

2

2

2.5

2.5

2.5

3

α

tol.(+2)

90°

90°

90°

90°

90°

90°

90°

90°

90°

90°

90°

60°

60°

b

L≤125

12

14

16

18

22

26

30

34

38

42

46

50

54

125＜L ≤ 200

/

/

/

24

28

32

36

40

44

48

52

56

60

L＞200

/

/

/

/

/

45

49

53

57

61

65

69

73

dk

Max.= Nominal

6

8

10

12

16

20

24

27

30

33

36

36

39

Min.

5.7

7.64

9.64

11.57

15.57

19.48

23.48

26.48

29.48

32.38

35.38

35.38

38.38

ds

Max.=Nominal

3

4

5

6

8

10

12

14

16

18

20

22

24

Min.

2.86

3.82

4.82

5.82

7.78

9.78

11.73

13.73

15.73

17.73

19.67

21.67

23.67

e

Min.

2.3

2.87

3.44

4.58

5.72

6.86

9.15

11.43

11.43

13.72

13.72

16

16

k

Max.

1.7

2.3

2.8

3.3

4.4

5.5

6.5

7

7.5

8

8.5

13.1

14

s

Nominal

2

2.5

3

4

5

6

8

10

10

12

12

14

14

Min.

2.02

2.52

3.02

4.02

5.02

6.02

8.025

10.025

10.025

12.032

12.032

14.032

14.032

Max.

2.1

2.6

3.1

4.12

5.14

6.14

8.175

10.175

10.175

12.212

12.212

14.212

14.212

t

Max.=Nominal

1.2

1.8

2.3

2.5

3.5

4.4

4.6

4.8

5.3

5.5

5.9

8.8

10.3

Min.

0.95

1.55

2.05

2.25

3.2

4.1

4.3

4.5

5

5.2

5.6

8.44

9.87

Thousand pieces of steel weigh ≈kg 

-

-

-

-

-

-

-

-

-

-

-

-

-

Thread length b 

-

-

-

-

-

-

-

-

-

-

-

-

-

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