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Coefficient of Friction

CoefficientOfFrictionChart.pdf

Coefficient of Friction
Extreme care is needed in using friction coefficients. Please use additional independent references.  For any specific application the ideal method of determining the coefficient of friction is by trials.  A short table is included above the main table to illustrate how the coefficient of friction is affected by surface films.  When a metal surface is perfectly clean in a vacuum, the friction is much higher than the normal accepted value and seizure can easily occur.
Effect of Oxide film, Sulfide film on Coefficient of Static Friction
MATERIAL Clean & Dry Thick Oxide Film Sulfide Film
Steel-Steel 0.78 0.27 0.39
Copper-Copper 1.21 0.76 0.74
Coefficient of Friction
Mat. 1 Mat 2. Dry Greasy
Static Sliding Static Sliding
Aluminum Alluminum 1.05-1.35 1.4 0.3
Aluminum Mild Steel 0.61 0.47
Brake Material Cast Iron 0.4
Brake Material Cast Iron (Wet) 0.2
Brass Cast Iron 0.3
Brick Wood 0.6
Bronze Cast Iron 0.22
Bronze Steel 0.16
Cadmium Cadmium 0.5 0.05
Cadmium Mild Steel 0.46
Cast Iron Cast Iron 1.1 0.15 0.07
Cast Iron Oak 0.49 0.075
Chromium Chromium 0.41 0.34
Copper Cast Iron 1.05 0.29
Copper Copper 1.0 0.08
Copper Mild Steel 0.53 0.36 0.18
Copper-Lead Alloy Steel 0.22
Diamond Diamond 0.1 0.05-0.1
Diamond Metal 0.1-0.15 0.1
Glass Glass 0.9-1.0 0.4 0.1-0.6 0.09-0.12
Glass Metal 0.5-0.7 0.2-0.3
Glass Nickel 0.78 0.56
Graphite Graphite 0.1 0.1
Graphite Steel 0.1 0.1
Graphite (In vacuum) Graphite (In vacuum) 0.5-0.8
Hard Carbon Hard Carbon 0.16 0.12-0.14
Hard Carbon Steel 0.14 0.11-0.14
Iron Iron 1.0 0.15-0.2
Lead Cast Iron 0.43
Leather Wood 0.3-0.4
Leather Metal (Clean) 0.6 0.2
Leather Metal (Wet) 0.4
Leather Oak (Parallel grain) 0.61 0.52
Magnesium Magnesium 0.6 0.08
Nickel Nickel 0.7-1.1 0.53 0.28 0.12
Nickel Mild Steel 0.64 0.178
Nylon Nylon 0.15-0.25
Oak Oak (Parallel grain) 0.62 0.48
Oak Oak (cross grain) 0.54 0.32 0.072
Platinum Platinum 1.2 0.25
Plexiglas Plexiglas 0.8 0.8
Plexiglas Steel 0.4 – 0.5 0.4 – 0.5
Polystyrene Polystyrene 0.5 0.5
Polystyrene Steel 0.3-0.35 0.3-0.35
Polythene Steel 0.2 0.2
Rubber Asphalt (Dry) 0.5-0.8
Rubber Asphalt (Wet) 0.25-0.0.75
Rubber Concrete (Dry) 0.6-0.85
Rubber Concrete (Wet) 0.45-0.75
Saphire Saphire 0.2 0.2
Silver Silver 1.4 0.55
Sintered Bronze Steel 0.13
Solids Rubber 1.0-4.0
Steel Aluminium Bros 0.45
Steel Brass 0.35 0.19
Steel (Mild) Brass 0.51 0.44
Steel (Mild) Cast Iron 0.23 0.183 0.133
Steel Cast Iron 0.4 0.21
Steel Copper Lead Alloy 0.22 0.16 0.145
Steel (Hard) Graphite 0.21 0.09
Steel Graphite 0.1 0.1
Steel (Mild) Lead 0.95 0.95 0.5 0.3
Steel (Mild) Phos Bros 0.34 0.173
Steel Phos Bros 0.35
Steel (Hard) Polythened 0.2 0.2
Steel (Hard) Polystyrene 0.3-0.35 0.3-0.35
Steel (Mild) Steel (Mild) 0.74 0.57 0.09-0.19
Steel (Hard) Steel (Hard) 0.78 0.42 0.05-0.11 0.029-.12
Steel Zinc (Plated on steel) 0.5 0.45
Teflon Steel 0.04 0.04 0.04
Teflon Teflon 0.04 0.04 0.04
Tin Cast Iron .32
Tungsten Carbide Tungsten Carbide 0.2-0.25 0.12
Tungsten Carbide Steel 0.4-0.6 0.08-0.2
Tungsten Carbide Copper 0.35
Tungsten Carbide Iron 0.8
Wood Wood (clean) 0.25-0.5
Wood Wood (Wet) 0.2
Wood Metals(Clean) 0.2-0.6
Wood Metals(Wet) 0.2
Wood Brick 0.6
Wood Concrete 0.62
Zinc Zinc 0.6 0.04
Zinc Cast Iron 0.85 0.21

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