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Design Resources | Friction Design Data
The frictional force for Static Friction can be expressed as:
Fmax= μ Fn
where
Fmax= Frictional force (N, lb)
μ = static (μ s ) or kinetic (μ k ) frictional coefficient
Fn = Applied Normal force (N, lb)
The frictional force for Dynamic Friction can be expressed as:
For an object pulled or pushed horizontally, the normal force - N - is simply the weight : N = m g
Where:
m = Mass (kg, slugs )
g = Gravity (9.81 m/s2 , 32 ft/s2)
| Material |
Against Material |
Static Coefficient of Friction |
| Dry Contact |
Lubricated Contact |
|
Aluminum |
Aluminum |
1.10 -1.35 |
.30 |
| Aluminum-Bronze Alloy |
Steel |
.46 |
- |
| Aluminum |
Steel |
.61 |
- |
| Brake (Composite) |
Cast Iron |
.40 |
.21 (wet) |
| Brass |
Steel |
.50 |
.19 |
| Brass |
Cast Iron |
.28 |
|
| Brick |
Wood |
.60 |
- |
| Bronze |
Cast Iron |
.21 |
- |
| Bronze Sintered |
Steel |
- |
.12 |
| Bronze |
Steel |
|
.16 |
| Cadmium |
Cadmium |
.50 |
.05 |
| Cadmium |
Chromium (Chrome) |
.40 |
.35 |
| Cadmium |
Steel, Mild |
.46 |
|
| Carbon |
Carbon |
.15 |
.12 - .14 |
| Carbon |
Steel |
.14 |
.12 - .14 |
| Cast Iron |
Cast Iron |
1.1 |
.08 |
| Cast Iron |
Copper |
1.05 |
- |
| Cast Iron |
Oak Wood |
.485 |
.08 |
| Cast Iron |
Steel |
.40 |
.21 |
| Cast Iron |
Zinc |
.85 |
- |
| Chromium (Chrome) |
Chromium (Chrome) |
.41 |
.34 |
| Colbalt (70°C) |
Cobalt |
.3 |
- |
| Concrete |
Rubber |
1.0 |
.30 (wet) |
| Concrete |
Wood |
.62 |
- |
| Copper |
Cast Iron |
1.05 |
- |
| Copper |
Copper |
1.00 |
.08 |
| Copper |
Glass |
.94 |
- |
| Copper |
Steel |
.53 |
- |
| Copper-Lead Alloy |
Steel |
.22 |
- |
| Cork |
Iron |
.35 |
- |
| Diamond |
Diamond |
.10 |
.05 - .10 |
| Diamond |
Metal |
.10 - .15 |
.10 |
| Glass |
Glass |
.90 - 1.0 |
.10 - .60 |
| Glass |
Metal |
.50 - .70 |
.20 - .30 |
| Glass |
Nickel |
.78 |
.57 |
| Graphite |
Graphite |
.10 |
.10 |
| Graphite |
Steel |
.1 |
.1 |
| Horseshoe |
Concrete |
.67 |
- |
| Horseshoe |
Rubber |
.28 |
- |
| Ice |
Wood |
.05 |
- |
| Ice |
Steel |
.04 |
- |
| Iron |
Iron |
1.0 |
.15 -. .20 |
| Lead |
Cast Iron |
.41 |
- |
| Leather |
Iron |
.3 |
|
| Leather |
Wood |
.30 - .40 |
- |
| Leather |
Metal |
.60 |
- |
| Leather (Greasy) |
Iron |
.2 - .25 |
|
| Magnesium |
Magnesium |
.60 |
.079 |
| Masonry |
Brick |
.65 |
- |
| Nickel |
Nickel |
.70 |
.28 |
| Nylon |
Nylon |
.15 - .25 |
- |
| Oak |
Oak |
.61 |
- |
| Paper |
Cast Iron |
.19 |
- |
| Phosphor Bronze |
Steel |
.35 |
- |
| Platinum |
Platinum |
1.20 |
.25 |
| Plexiglas |
Plexiglas |
.80 |
.80 |
| Plexiglas |
Steel |
.40 - .50 |
.40 - .50 |
| Polyethene |
Steel |
.2 |
.2 |
| Polystyrene |
Polystyrene |
.50 |
.50 |
| Polystyrene |
Steel |
.30 - .35 |
.30 - .35 |
| Rubber |
Rubber |
1.15 |
- |
| Rubber |
Asphalt |
.9 |
- |
| Rubber |
Concrete |
.6 |
- |
| Rubber (60 A Belt) |
Stainless Steel 316 |
.64 |
- |
| Rubber (60 A Belt) |
Rubber (40 A Belt) |
.62 |
- |
| Rubber (60 A Belt) |
Rubber (60 A Belt) |
.73 |
- |
| Rubber (60 A Belt) |
Tool Steel |
.86 |
- |
| Rubber (60 A Belt) |
Tungsten Carbide |
.62 |
- |
| Rubber (60 A Belt) |
UHMW |
.56 |
- |
| Rubber (60 A Belt) |
Urethane 50 |
.60 |
- |
| Rubber (60 A Belt) |
Urethane 80A |
.70 |
- |
| Rubber (60 A Belt) |
Urethane |
.67 |
- |
| Silver |
Silver |
1.40 |
.52 |
| Skin, Human |
Metals (63 Ra) |
.9 |
- |
| Steel |
Steel |
.80 |
.16 |
| Teflon |
Steel |
.04 |
.04 |
| Teflon |
Teflon |
.05 - .20 |
.04 |
| Tin |
Cast Iron |
.31 |
- |
| Tire, Rubber |
Asphalt |
.71 |
- |
| Tire, Rubber |
Grass |
.36 |
- |
| Tungsten Carbide |
Steel |
.40 - .60 |
.10 - .20 |
| Tungsten Carbide |
Tungsten Carbide |
.20 - .25 |
.12 |
| Wood |
Wood |
.25 - .50 |
.20 |
| Wood |
Metals |
.20 - .60 |
.20 (wet) |
| Zinc |
Zinc |
.60 |
.04 |
Static friction is friction between two or more solid objects that are not moving relative to each other. For example, static friction can prevent an object from sliding down a sloped surface. The coefficient of static friction, typically denoted as μs , is usually higher than the coefficient of kinetic friction.
Material |
Sliding |
Dry |
Lubricated |
Aluminum on aluminum |
- |
- |
Canvas belt on rubber lagging |
- |
- |
Canvas belt, stitched, on steel |
0.20 |
0.10 |
Canvas belt, woven, on steel |
0.22 |
0.10 |
Cast iron on asbestos, fabric brake material |
0.35-0.40 |
- |
Cast iron on brass |
0.30 |
- |
Cast iron on bronze |
0.22 |
0.07-0.08 |
Cast iron on cast iron |
0.15 |
0.06-0.10 |
Cast iron on copper |
0.29 |
- |
Cast iron on lead |
0.43 |
0.13-0.36 |
Cast iron on leather |
- |
0.07-0.20 |
Cast iron on oak (parallel) |
0.30-0.50 |
- |
Cast iron on magnesium |
0.25 |
0.133 |
Cast iron on steel, mild |
0.23 |
- |
Cast iron on tin |
0.32 |
- |
Cast iron on zinc |
0.21 |
- |
Earth on earth |
- |
- |
Glass on glass |
0.40 |
- |
Hemp rope on wood |
0.40-0.70 |
- |
Nickel on nickel |
0.53 |
0.12 |
Oak on leather (parallel) |
0.30-0.50 |
- |
Oak on oak (parallel) |
0.48 |
0.16 |
Oak on oak (perpendicular) |
0.32 |
0.07 |
Rubber tire on pavement |
0.75-0.85 |
0.5-0.7* |
Steel on ice |
0.01 |
- |
Steel, hard, on babbit |
0.33-0.35 |
0.05-0.16 |
Steel, hard, on steel, hard |
0.42 |
0.03-0.12 |
Steel, mild, on aluminum |
0.47 |
- |
Steel, mild, on brass |
0.44 |
- |
Steel, mild, on bronze |
0.34 |
0.17 |
Steel, mild, on copper |
0.36 |
0.18 |
Steel, mild, on steel, mild |
0.57 |
0.09-0.19 |
Stone masonry on concrete |
- |
- |
Stone masonry on ground |
- |
- |
Wrought iron in bronze |
0.18 |
… |
Wrought iron on wrought iron |
0.44 |
0.08-0.10 |
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