Al Metal Special Metal Parts

Pre-load and torque figures for screws with fine thread

This table contains information on pre-load and torque figures for bolts and screws with metric fine thread and head dimensions as in DIN 912, 931, 933 etc.

The figures M_a in this table include:

a) coefficient of friction microns total = 0.14
b) 90% of minimum elongation
c) torque figures when assembling fasteners

The coefficient of friction of microns total = 0.14 applies for fasteners without coating (self colour) when slightly lubricated. Additional lubrication of the thread will substantially alter the coefficient of friction, leading to uncontrollable pre-load situations. Pre-load situations will be also influenced by the fastening methods and tools used. The following figures are guidelines only.

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