Page 675 - Mastik®

Estimation of screw diameters Selection of fasteners
according to VDI guideline 2230 1)

The following procedure allows a rough C The required maximum preload force Example:
estimate to be made of the required screw FM max. is found by proceeding from this A joint is loaded dynamically and eccen-
dimensions for a particular screwed con- force FM min. by: trically by the axial force FA = 8500 N. The
nection and temperature around 20 °C, 2 steps for tightening the screw with screw of strength class 12.9 will be as-
in correspondence with the details in a motorized/pneumatic screwdriver sembled with a manual torque wrench.
VDI 2230. The result should be checked which is set for a certain tightening
mathematically in each case. torque A 10000 N is the next higher force to FA
or in column 1.
1 step for tightening with a torque B 2 steps for «eccentric and dynamic
A Select in column 1 the next higher wrench/or precision motorized screw- axial force» lead to FM min. = 25000 N
force to the work force FA,Q acting on driver, which is set and checked by C 1 step for «tightening with manual torque
the bolted joint. means of dynamic torque measure- wrench» leads to FM max. = 40000 N
B The required minimum preload FM min. ment or elongation measurement of D for FM max. = 40000 N thread size M10
is found by proceeding from this the screw – or is found in column 2 (property class
number: 0 step for «turn of the nut» method or 12.9).
4 steps for static or dynamic trans- yield point controlled method.
verse (shear) force
D Once the preload (force) has been esti-
F Q
F Q mated, the correct screw size is found
next to it in column 2 to 4 underneath
the appropriate strength class.
or
2 steps for dynamic,
1 2 3 4
eccentric axial force
Nominal diameter
F A Force in mm
N Property class
12.9 10.9 8.8
F A
250
400
630
or
1000 M 3 M 3 M 3
1 step for either dynamic and centrical 1600 M 3 M 3 M 3
or static and eccentric force 2500 M 3 M 3 M 4
4000 M 4 M 4 M 5
F A 6300 M 4 M 5 M 6
F A
10000 M 5 M 6 M 8
16000 M 6 M 8 M10
25000 M 8 M10 M12
F A
F A 40000 M10 M12 M14
63000 M12 M14 M16
or 100000 M16 M18 M20
0 step for static, 160000 M20 M22 M24
250000 M24 M27 M30
centrical axial force.
400000 M30 M33 M36
F A
630000 M36 M39

F A

1) VDI = Verein Deutscher Ingenieure (Association of German engineers)