FRICTION COEFFICIENT GUIDE VALUES FOR DIFFERENT MATERIALS AND LUBRICATION STATES IN BOLTED JOINTS


The coefficients of friction in the thread μG and in the bearing surfaces of the head of the bolt or the nut μK are given in the following chart for guidance purpose. These coefficient of friction values are according to VDI 2230 standard. For more information about systematic procedure for calculating bolted joints in the form of calculated steps, visit VDI 2230.



Friction Coefficient Guide Values in Bolted Joints
Range for μG and μK Typical Examples
Material - Surfaces Lubricants
0.04 to 0.10 Metallically bright
Black oxide coating
Phosphate conversion coating
Electroplated coatings such as
Zn, Zn/Fe, Zn/Ni
Zinc laminated coatings
Solid lubricants, such as MoS2,
graphite, PTFE, PA, PE, PI in lubricating varnishes, as top coats or in pastes;
liquefied wax;
wax dispersions
0.08 to 0.16 Metallically bright
Black oxide coating
Phosphate conversion coating
Electroplated coatings such as
Zn, Zn/Fe, Zn/Ni
Zinc laminated coatings
Al and Mg alloys
Solid lubricants, such as MoS2,
graphite, PTFE, PA, PE, PI in lubricating varnishes, as top coats or in pastes;
liquefied wax ;
wax dispersions, greases;
oils; delivery state
Hot-dip Galvanized  MoS2; graphite; wax dispersions
Organic coatings With integrated solid lubricant
or wax dispersion
Austenitic steel Solid lubricants or waxes; pastes
0.14 to 0.24 Austenitic steel Wax dispersions, pastes
Metallically bright
Phosphate conversion coating
Delivery state (lightly oiled)
Electroplated coatings such as
Zn, Zn/Fe, Zn/Ni
Zinc laminated coatings
None
0.20 to 0.35 Austenitic steel Oil
Electroplated coatings such as Zn, Zn/Fe;
Hot-dip galvanized
None
≥ 0.30 Electroplated coatings such as Zn/Fe, Zn/Ni
Austenitic steel
Al, Mg alloys
None
Source : From VDI 2230 Part-1 : Systematic calculation of high duty bolted joints - Joints with one cylindrical bolt.



Definitions / Abbreviations:

Austenitic Steel: Austenitic steel is the one of the class of stainless steel. Austenitic steel is the more corrosion resistant because of the high chromium content and nickel additions.

Fe: Iron.

Hot Dip Galvanization: A galvanization process to coat iron and steel with a layer of zinc by immersing the metal in a bath of molten zinc.

MoS2: Molybdenum disulfide.

Ni: Nickel.

PA: Polyamide.

PE: Polyethylene.

PI: Polyimide.

PTFE: Teflon.

Zn: Zinc.

Reference:
  • VDI 2230 Part-1 : Systematic calculation of high duty bolted joints - Joints with one cylindrical bolt