Friction Factor in Thread F1 of Bolted Connections

Thread surface

non-lubricated

lubricated

black or phosphate coating

0.14 to 0.21

0.12 to 0.15

galvanic zinc coating

0.13 to 0.18

0.12 to 0.17

cadmium plating

0.08 to 0.12

0.08 to 0.11