DIN 931 Hex Cap Screw (Partial Thread)

DIN 931 Hex Cap Screws – Partial Thread

ISO Equivalent: ISO 4014 | Metric Hex Bolts – Coarse Thread, Partial Thread

DIN 931 defines hex head cap screws with partial threading — the most common metric hex bolt for structural and mechanical applications. The unthreaded shank provides superior shear strength and allows for precise positioning in through-holes.

Quick Specifications

Thread Type
Coarse (Standard)
Threading
Partial
Size Range
M5 – M100
Property Classes
8.8, 10.9, 12.9
ISO Equivalent
ISO 4014

Why Partial Thread?

💪

Superior Shear Strength

Unthreaded shank resists shear loads better than threads. Critical for joints under lateral stress.

🎯

Precise Positioning

Smooth shank allows accurate alignment in clearance holes before threads engage the nut.

⚡

Reduced Fatigue Failure

Thread run-out away from the joint interface reduces stress concentration at critical points.

🔧

External Hex Drive

Use standard wrenches or sockets. Faster to install than internal drive fasteners.

Dimension Chart

Size Pitch (Coarse) Head Width (s) Head Height (k) Wrench Size Thread Length (b)*
M5 0.8 mm 8.0 mm 3.5 mm 8 mm 16 mm
M6 1.0 mm 10.0 mm 4.0 mm 10 mm 18 mm
M8 1.25 mm 13.0 mm 5.3 mm 13 mm 22 mm
M10 1.5 mm 16.0 mm 6.4 mm 16 mm 26 mm
M12 1.75 mm 18.0 mm 7.5 mm 18 mm 30 mm
M14 2.0 mm 21.0 mm 8.8 mm 21 mm 34 mm
M16 2.0 mm 24.0 mm 10.0 mm 24 mm 38 mm
M20 2.5 mm 30.0 mm 12.5 mm 30 mm 46 mm
M24 3.0 mm 36.0 mm 15.0 mm 36 mm 54 mm
M30 3.5 mm 46.0 mm 18.7 mm 46 mm 66 mm

*Thread length (b) shown for bolts ≤125mm. Formula: b = 2d + 6mm for L ≤ 125mm

Property Classes

8.8
Class 8.8
Medium Carbon Steel
Tensile
116,000 PSI
Yield
92,800 PSI

Equivalent to SAE Grade 5. Standard choice for general machinery and construction.

10.9
Class 10.9
Alloy Steel, Quenched & Tempered
Tensile
150,800 PSI
Yield
136,300 PSI

Equivalent to SAE Grade 8. Heavy-duty structural, automotive, and equipment applications.

12.9
Class 12.9
Alloy Steel, Heat Treated
Tensile
176,900 PSI
Yield
159,500 PSI

Highest strength available. Critical joints, motorsport, high-stress machinery.

Coarse Thread Pitches

📏 Thread Pitch Reference (Coarse/Standard)

DIN 931 uses coarse thread pitch — the metric standard. Coarse pitch doesn't need to be specified when ordering (it's assumed). Fine pitch fasteners (DIN 960) must always be called out.

M5
0.8
M6
1.0
M8
1.25
M10
1.5
M12
1.75
M14
2.0
M16
2.0
M20
2.5
M24
3.0
M30
3.5

DIN 931 vs DIN 933

💡 Which One Do I Need?

DIN 931 (Partial Thread):

  • Unthreaded shank below head
  • Better shear strength
  • Use with clearance holes
  • Standard for structural joints

DIN 933 (Full Thread):

  • Threads to the head
  • Maximum grip range flexibility
  • Use with tapped holes
  • Better for varying material thickness

Common Applications

🏗️
Structural Steel
🚗
Automotive
🏭
Heavy Machinery
🔩
Flanged Joints
🚜
Agricultural
🏢
Construction

Shop DIN 931 Hex Cap Screws

Available in Class 8.8, 10.9, and 12.9. Zinc plated, plain, and stainless steel finishes.

Shop Hex Bolts

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