Coefficient of friction
#1 What is the coefficient of friction?
The coefficient of friction provides information about the extent to which materials adhere to each other.
The smaller the value, the lower the adhesion.
The sealing effect of O-rings can be negatively affected by excessive adhesion. In addition, the O-ring can also twist due to excessive adhesion. It is therefore always important to ensure that the adhesion between the O-ring and the sealing surface is kept to a minimum.
This applies in particular to dynamic (moving) applications.
To ensure that you always make the right choice of material, we have compiled a table with the most important O-ring materials and their coefficients of friction.
Material | Friction |
|---|---|
VMQ (silicone) | High |
FVMQ | High |
NBR | Medium |
EPDM | Medium |
FKM | Medium |
FFKM (ECOLAST) | Medium |
FEP coated | Low |
PTFE | Low |
#2 How can I reduce the coefficient of friction?
In addition to the choice of material, there are also other ways to minimize friction between the O-ring and the sealing surface.
The 6 most important ways to reduce friction
1. Increase the surface quality of the sealing surfaces
2. Reduce the compression of the O-ring
3. Use assembly grease
4. Use O-rings with FEP coating or pure PTFE O-rings
5. Coat standard O-ring materials such as NBR or FKM with PTFE
6. Talcumize O-rings (especially suitable for silicone or FVMQ O-rings)
