Friction Coefficients of Common Materials
Reference table for static and kinetic friction coefficients (μ) for common engineering materials
Friction Coefficients Comparison Table
| Material Pair | Static μ | Kinetic μ |
|---|---|---|
| Steel on Steel (clean, dry) | 0.74 | 0.57 |
| Aluminum on Steel | 0.61 | 0.47 |
| Copper on Steel | 0.53 | 0.36 |
| Brass on Steel | 0.35 | 0.27 |
| Bronze on Steel | 0.42 | 0.35 |
| Rubber on Concrete | 1.0 | 0.8 |
| Rubber on Steel | 0.85 | 0.7 |
| Wood on Wood (dry) | 0.25 | 0.20 |
| Glass on Glass | 0.94 | 0.4 |
| Plastic (HDPE) on Steel | 0.20 | 0.15 |
| Plastic (PTFE) on Steel | 0.04 | 0.04 |
| Concrete on Steel | 0.60 | 0.50 |
| Lead on Steel | 0.17 | 0.14 |
Friction Coefficients Comparison Chart
About Friction Coefficients
The friction coefficient (μ) is a dimensionless property that quantifies the resistance to sliding motion between two contacting surfaces. It is a key parameter in tribology, mechanical design, and materials engineering. Friction coefficients are divided into:
- Static Friction (μs): Resistance to the start of motion between surfaces.
- Kinetic Friction (μk): Resistance once surfaces are already sliding.
Applications of Friction Coefficients in Engineering
Understanding friction coefficients is essential for a wide range of engineering and design applications, including:
- Bearing and Gear Design: Optimizing contact surfaces to reduce wear and energy losses.
- Brake and Clutch Systems: Ensuring reliable performance and safety under various loads.
- Conveyor Systems: Calculating forces needed to move materials efficiently.
- Manufacturing Processes: Predicting tool-workpiece interactions and minimizing material wear.
- Material Selection: Choosing appropriate metals, plastics, or composites to achieve desired friction and wear properties.
Accurate knowledge of friction coefficients helps engineers ensure components meet design specifications, safety standards, and performance targets, making it a fundamental property in mechanical and materials engineering.