DIN 7984 – Hex Socket Low Cap Head Screw
DIN 7984 is the industry standard for hexagon socket head cap screws with low head. These fasteners are specifically designed for applications where head height clearance is restricted, preventing the use of a standard DIN 912 bolt. Unlike the DIN 6912 variant, DIN 7984 features a solid hexagonal drive without a pilot hole. This makes it a more cost-effective and straightforward solution for general mechanical engineering, automotive assembly, and furniture manufacturing where a reduced profile is necessary but specialized centering tools are not required.
| DIN 7984 - Dimensions | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thread Size | M3 | M4 | M5 | M6 | M8 | M10 | M12 | M14 | M16 | M18 | M20 | M22 | M24 | |
| dk | Max | 5.5 | 7 | 8.5 | 10 | 13 | 16 | 18 | 21 | 24 | 27 | 30 | 33 | 36 |
| Min | 5.32 | 6.78 | 8.28 | 9.78 | 12.73 | 15.73 | 17.73 | 20.67 | 23.67 | 26.67 | 29.67 | 32.61 | 35.61 | |
| k | Max | 2 | 2.8 | 3.5 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
| Min | 1.86 | 2.66 | 3.32 | 3.82 | 4.82 | 5.82 | 6.78 | 7.78 | 8.78 | 9.78 | 10.73 | 11.73 | 12.73 | |
| t | Nom | 1.5 | 2.3 | 2.7 | 3 | 3.8 | 4.5 | 5 | 5.3 | 5.5 | 6.5 | 7.5 | 8 | 8 |
| Max | 1.62 | 2.42 | 2.82 | 3.12 | 3.95 | 4.65 | 5.15 | 5.45 | 5.65 | 6.68 | 7.68 | 8.18 | 8.18 | |
| Min | 1.38 | 2.18 | 2.58 | 2.88 | 3.62 | 4.35 | 4.85 | 5.15 | 5.35 | 6.32 | 7.32 | 7.82 | 7.82 | |
| s | Nom | 2 | 2.5 | 3 | 4 | 5 | 7 | 8 | 10 | 12 | 12 | 14 | 14 | 17 |
| Max | 2.1 | 2.6 | 3.1 | 4.12 | 5.14 | 7.175 | 8.175 | 10.175 | 12.212 | 12.212 | 14.212 | 14.212 | 17.23 | |
| Min | 2.02 | 2.52 | 3.02 | 4.02 | 5.02 | 7.025 | 8.025 | 10.025 | 12.032 | 12.032 | 14.032 | 14.032 | 17.05 | |
| e | Min | 2.3 | 2.87 | 3.44 | 4.58 | 5.72 | 8.01 | 9.15 | 11.43 | 13.72 | 13.72 | 16 | 16 | 19.44 |
| v | Max | 0.3 | 0.4 | 0.5 | 0.6 | 0.8 | 1 | 1.2 | 1.4 | 1.6 | 1.8 | 2 | 2.2 | 2.4 |
| r | Min | 0.1 | 0.2 | 0.2 | 0.25 | 0.4 | 0.4 | 0.6 | 0.6 | 0.6 | 0.6 | 0.8 | 0.8 | 0.8 |
| lf | Max | 0.51 | 0.6 | 0.6 | 0.68 | 1.02 | 1.02 | 1.87 | 1.87 | 1.87 | 1.87 | 2.04 | 2.04 | 2.04 |
| dw | Min | 4.84 | 6.2 | 7.7 | 9.2 | 12.03 | 15.03 | 17.03 | 19.83 | 22.83 | 25.83 | 28.83 | 31.61 | 34.61 |
| da | Max | 3.6 | 4.7 | 5.7 | 6.8 | 9.2 | 11.2 | 13.7 | 15.7 | 17.7 | 20.2 | 22.4 | 24.4 | 26.4 |
| ds | Max | 3 | 4 | 5 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 22 | 24 |
| Min | 2.86 | 3.82 | 4.82 | 5.82 | 7.7 | 9.78 | 11.73 | 13.73 | 15.73 | 17.73 | 19.67 | 21.67 | 23.67 | |
| b (Ref) | l ≤ 125 | 12 | 14 | 16 | 18 | 22 | 26 | 30 | 34 | 38 | 42 | 46 | 50 | 54 |
| l ≤ 200 | — | — | — | — | 28 | 32 | 36 | 40 | 44 | 48 | 52 | 56 | 60 | |
| l > 200 | — | — | — | — | — | — | — | — | 57 | 61 | 65 | 69 | 73 | |
Note: All measurement are in mm
Disclaimer: The dimensions presented on this page are based on the applicable industry standard. However, actual product measurements may vary slightly due to manufacturing practices, material selection, surface finish, and specified tolerance classes. Buyers and sourcing professionals are encouraged to verify final specifications with the manufacturer or supplier prior to procurement, particularly for critical applications.
Legend
- dk – Head diameter (outer diameter of the low profile head).
- da – Transition diameter (max); the limit of the transition from the shank to the head.
- ds – Shank diameter (nominal diameter of the screw body).
- k – Head height; specifically designed to be lower than standard socket caps.
- s – Width across flats (Nominal size for the required Allen key/Hex bit).
- t – Depth of the internal hexagon socket.
- e – Width across corners (minimum) of the hexagon socket.
- dw – Minimum bearing surface diameter under the head.
- b – Thread length (Reference length based on the screw length $l$).
- r – Underhead fillet radius (min).
- v – Maximum underhead fillet depth/curvature.
- lf – Thread run-out (maximum distance from the last full thread to the bearing surface).
- Ref (Reference value) – Dimensions provided for design guidance. These are theoretical values used to calculate geometry rather than strict inspection requirements.
Technical Note
- Key Difference (DIN 7984 vs. DIN 6912): While both are low-profile socket caps, DIN 6912 features a small "pilot hole" (recess) at the bottom of the hex socket. DIN 7984 has a standard flat-bottomed hex socket.
- Drive Compatibility: DIN 6912 often requires a specific "pilot" hex key for full engagement, whereas DIN 7984 uses standard ISO 2936 (Allen) keys.
- Load Capacity: Due to the reduced head height and socket depth, these screws cannot reach the full loadability of a standard ISO 4762 (DIN 912) screw. They are typically classed as 8.8 or 10.9; 12.9 is rare due to the risk of head shear.
- Shank Calculation: The maximum unthreaded portion max lg is calculated as: l (nominal length) - b (ref thread length).
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Standard Lengths:
- M3 – M10: 5 mm to 100 mm
- M12 – M24: 20 mm to 100 mm