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Typical Coefficient of Friction Values for Common Materials


 

The static and kinetic friction coefficient values reference table shown in this article will be helpful for finding the COF values of commonly used materials.

 

Static and Kinetic coefficient of friction

 

 

 

 

 

 

 

 

Coefficient of friction Typical Coefficient of Friction Values for Common Materials

Fig.1: Showing the Concept of Coefficient of Friction

 

 

 

 

 

 

 

Image Source: Wiki

Both the types of COF can be expressed by the same equation as below (refer with the Fig.1):

μ= Ff/N………………Eq.1

Where,

Ff – Frictional force along the surface

N – Normal reaction perpendicular to the surface.

μ – Coefficient of friction between the block and the surface, for Static friction it is termed a μs and for kinetic or sliding friction it is termed as μs or μk .

Then what is the difference between static and kinetic friction coefficient?

For static COF the block must be in static or non-moving condition, i.e., you have to take the friction force value of the force which is applied to the block for giving motion to it but the force value has not yet reached to the limit that can move the block.

For sliding or kinetic friction coefficient, you have to consider the friction force value of the moving block.

 

Friction Coefficients table

 

Material-1 Material-2 Coefficient of static friction ( µs) Coefficient of sliding friction ( µk)
Aluminium (Al) Aluminium (Al) 0.42 0.34
Aluminium (Al) Copper (Cu) 0.28 0.23
Aluminium (Al) Steel 0.35 0.25
Aluminium (Al) Titanium 0.34 0.29
Aluminium (Al) PTFE 0.19
Aluminium (Al) Teflon 0.19 0.18
Aluminium (Al) Chromium (Cr) 0.27 0.22
Aluminium (Al) Nickel (Ni) 0.33 0.25
Aluminium (Al) Mild Steel 0.61
Aluminium (Al) Glass 0.17 0.14
Aluminium (Al) Graphite 0.16
Brake Material Cast Iron (Fe) 0.40
Brass Cast Iron (Fe) 0.3
Brass Steel 0.35 0.24
Brass Glass 0.2
Bronze Titanium 0.36 0.27
Bronze Ice 0.02
Bronze Cast Iron (Fe) 0.22
Bronze Steel 0.16
Cadmium (Cd) Cadmium (Cd) 0.79
Cadmium (Cd) Cast Iron (Fe) 0.52
Cadmium (Cd) Mild Steel 0.46
Cobalt Cobalt 0.56
Cobalt Chromium (Cr) 0.41
Cobalt Cast Iron (Fe) 0.41
Cobalt Lead (Pb) 0.55
Chromium (Cr) Chromium (Cr) 0.46
Chromium (Cr) Cobalt 0.41
Chromium (Cr) Cast Iron (Fe) 0.48
Chromium (Cr) Nickel (Ni) 0.59
Chromium (Cr) Lead (Pb) 0.53
Chromium (Cr) Alumina 0.50
Chromium (Cr) Zerconia 0.61
Chromium (Cr) Teflon 0.09 0.08
Chromium (Cr) Aluminium (Al) 0.27 0.22
Chromium (Cr) Steel 0.25 0.21
Copper (Cu) Copper (Cu) 0.55
Copper (Cu) Cobalt 0.44
Copper (Cu) Chromium (Cr) 0.46
Copper (Cu) Cast Iron (Fe) 0.5
Copper (Cu) Nickel (Ni) 0.49
Copper (Cu) Zinc 0.56
Copper (Cu) Aluminium (Al) 0.28 0.23
Copper (Cu) Silver 0.48
Copper (Cu) Steel 0.32 0.25
Copper (Cu) Stainless Steel 0.23 0.21
Copper (Cu) Teflon 0.13 0.11
Copper (Cu) Zinc 0.56
Cast Iron (Fe) Cast Iron (Fe) 0.51
Cast Iron (Fe) Cobalt 0.41
Cast Iron (Fe) Chromium (Cr) 0.48
Cast Iron (Fe) Manganese (Mn) 0.51
Cast Iron (Fe) Molybdenum (Mo) 0.46
Cast Iron (Fe) Titanium 0.49
Cast Iron (Fe) Zinc 0.55
Cast Iron (Fe) Lead (Pb) 0.54 0.43
Cast Iron (Fe) Steel 0.4
Cast Iron (Fe) Tin (Sn) 0.55 0.32
Gold (Au) Gold (Au) 0.49
Gold (Au) Silver (Ag) 0.53
Gold (Au) Lead (Pb) 0.61
Graphite Graphite 0.18 0.14
Graphite Aluminium (Al) 0.16
Graphite Steel 0.18
Graphite Glass 0.15
Glass Aluminium (Al) 0.17 0.14
Glass Steel 0.13 0.12
Glass Teflon 0.1 0.1
Glass Brass 0.19
Glass Steel 0.13 0.12
Glass Glass 0.9
Silver (Ag) Silver (Ag) 0.5
Silver (Ag) Gold (Au) 0.53
Silver (Ag) Copper (Cu) 0.48
Silver (Ag) Cast Iron (Fe) 0.49
Silver (Ag) Lead (Pb) 0.73
Silver (Ag) Alumina 0.37
Silver (Ag) Zirconium 0.39
Steel Steel 0.31 0.23
Steel Aluminium (Al) 0.47 0.38
Steel Copper (Cu) 0.32 0.25
Steel Titanium (Ti) 0.48 0.48
Steel Nylon 0.35
Steel Teflon 0.27 0.27
Steel ABS 0.3 0.35
Steel PVC 0.53 0.38
Steel Chromium (Cr) 0.25 0.21
Steel Glass 0.13 0.12
Steel Graphite 0.18
Titanium Vanadium alloy (Ti-6Al-4V) Titanium Vanadium alloy (Ti-6Al-4V) 0.36 0.3
Titanium Vanadium alloy (Ti-6Al-4V) Bronze 0.36 0.27
Titanium Vanadium alloy (Ti-6Al-4V) Steel 0.36 0.31
Titanium Vanadium alloy (Ti-6Al-4V) Aluminium 0.41 0.38
Titanium Vanadium alloy (Ti-6Al-4V) Chromium 0.38 0.33
Silicon Carbide (SiC) Silicon Carbide (SiC) 0.52
Silicon Carbide (SiC) Silicon Nitride (SiN) 0.53
Tungsten Carbide Tungsten Carbide 0.22
Tungsten Carbide Steel 0.45
Tungsten Carbide Copper (Cu) 0.35
Tungsten Carbide Cast Iron (Fe) 0.8
Teflon Chromium 0.09 0.08
Teflon Nickel 0.15 0.12
Teflon Aluminium (Al) 0.19 0.18
Teflon Glass 0.1 0.1
Teflon Steel 0.18 0.16
Teflon Titanium Vanadium alloy (Ti-6Al-4V) 0.23 0.21
Ice Ice 0.01 0.01
Ice Bronze 0.02
Leather Metal 0.61 0.25
Leather Wood 0.61 0.52
Wood Wood 0.25 0.129
Wood Brick 0.6
Wood Metal 0.3
Wood Concrete 0.61
Wood Snow 0.14
Brick Wood 0.6
Paper Paper 0.28
Bitumen or Asphalt (Wet) Rubber 0.25 – 0.75
Bitumen or Asphalt (dry) Rubber 0.9 0.5 – 0.8
Concrete (Dry) Rubber 0.6 – 0.85
Concrete (Wet) Rubber 0.45 – 0.75

Although, reliable sources (mentioned at the reference section) has been used for compiling the above COF table but still the values shown are approximate only. The friction coefficient value changes not only with material but also with the position and orientation of the participating materials. So, if you need accurate COF value, you must obtain it by experiment only.
Reference

    • ASM-VOL 18-FRICTION, LUBRICATION AND WEAR TECHNOLOGY

    • Friction Science and Technology FROM CONCEPTS to APPLICATIONS – By Peter J. Blau

About the author

Suvo

Suvo is a production engineer by profession and writer/blogger by passion. Apart from maintaining this blog, he also get some freelance work like: Mechanical design, CAD, CAE, Assignment report writing, Website design. Read More>>

  • Adonica

    Nothing I could say would give you undue cdreit for this story.

  • Anton

    What is the coefficient of static friction between silicon and graphite? thank you.

  • Anton

    What is the coefficient of static friction between silicon and graphite? thank you.

  • thamlett

    what would be the static and kinetic COF of PTFE impregnated, hardcoated aluminum on the same. I think the specification limit of 0.15 is too low for this application.

  • Nayara

    What is the coefficient of static friction between Nylon (Plastic) and Brass? thank you.

  • Milos

    How come there is a difference between Steel – Teflon and Teflon – Steel in table above. Or, for example Aluminum – Steel and Steel – Aluminum?

  • hambaAllah

    And what about rubber and metal?

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