Torque and preload for customized geometry and material

Calculate tightening torque, preload and surface pressure for hex head, socket head and countersunk screws. Customized head shapes, hole chamfers, reduced shanks and materials are available options.

Based on VDI 2230:2014

Fastener where torque will be applied

Screw Nut

Conical	80° 90° 100°
Head diameter of countersunk screw Ød	mm

Inside diameter of plane bearing area da	mm
Outside diameter of plane bearing area dw	mm

Clearance hole - ISO 273

Fine Medium Coarse

Hole chamfer
Chamfer diameter dha	mm

Reduced shank

Reduced shank
Reduced shank diameter dT	mm

Mechanical properties of material, thread size and friction

Property class of screw	50 70 80 3.6 4.6 4.8 5.6 5.8 6.8 8.8 9.8 10.9 12.9
Customized material
Minimum yield strength of screw Rp02	N/mm²
Utilization of yield strength %	95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5
Thread size	M 1 M 1.2 M 1.4 M 1.6 M 1.8 M 2 M 2.5 M 3 M 3.5 M 4 M 4.5 M 5 M 6 M 7 M 8 M 10 M 12 M 14 M 16 M 18 M 20 M 22 M 24 M 27 M 30 M 33 M 36 M 39 M 42 M 45 M 48 M 52 M 56 M 60 M 64 M 68
Thread friction value	0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.25 0.30 0.35
Nut/bolt head friction value	0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.25 0.30 0.35

Data used in calculation

Thread pitch P	mm
Pitch diameter d2	mm
Root diameter d3	mm
Clearance hole dh	mm
Stress area As	mm²

Results

Maximum allowable tightening torque MA	Nm
Maximum possible preload FM	kN
Maximum surface pressure under screw head/nut	N/mm²