Friction coefficient

This section provides basic information about the friction coefficient.

Friction coefficient 1:

For each selected load case, a coefficient of friction can be specified in the settings area (1).

The values to be entered are application-specific. Please check your load case in advance for possible friction areas and refer to the tables below for approximate values.

The friction coefficient describes the relationship of the contact pressure between two bodies. A distinction is made between sliding friction and static friction. The friction coefficient between the selected materials bust be included in the specification of a load case.

The table below contains approximate values, which you can use for the configuration of your load case.
Please note that friction depends on several different factors, e.g.:

material combination
surface
lubrication
temperature
moisture
wear
normal force

so that only guide values can be provided.

	Friction coefficient for multiple bearings! Please note a load case configuration may include several bearings. This will affect the approximate value of your friction coefficient. For more detailed information please contact the component manufacturer.

Static friction

Static friction is a force that prevents sliding of bodies that are in contact with each other. Static friction creates a bond between bodies through frictional connection. In TC3 Motion Designer the static friction is assumed to be 0.

Sliding friction

Sliding friction at the contact surfaces between bodies that move relative to each other. In some material combinations creep occurs, so that the friction force becomes speed-dependent. The sliding friction force is usually lower than the static friction force at the same normal force. The following table shows sliding friction coefficients for different material combinations.

material combination	Without lubrication		With lubrication
material combination	static	dynamic	static	dynamic
aluminum on aluminum	1.2	1.4	0.3	---
aluminum on mild steel	0.61	0.47	---	---
lead on cast iron	---	0.43	---	---
bronze on cast iron	---	0.22	---	---
bronze on steel	---	---	0.16	---
cadmium on mild steel	---	0.46	---	---
cadmium on cadmium	0.5	---	0.05	---
chromium on chromium	0.41	---	0.34	---
iron on iron	1	---	0.175	---
solid matter on rubber	2.5	---	---	---
mild steel on mild steel	0.74	0.57	---	0.1
mild steel on brass	0.51	0.44	---	---
mild steel on phosphor bronze	---	0.34	---	0.173
mild steel on lead	0.95	0.95	0.5	0.3
mild steel on cast iron	---	0.23	0.183	0.133
glass on nickel	0.78	0.56	---	---
glass on metal	0.6	---	0.25	---
glass on glass	0.95	0.4	0.35	0.1
graphite on steel	0.1	---	0.1	---
graphite on graphite	0.1	---	0.1	---
cast iron on cast iron	1.1	0.15	---	0.07
hard steel on hard steel	0.78	0.42	0.075	0.008
hard steel on graphite	0.21	---	0.09	---
hard steel on polystyrene	0.325	---	0.325	---
hard steel on polyethylene	0.2	---	0.2	---
magnesium on magnesium	0.6	---	0.08	---
brass on cast iron	---	0.3	---	---
nickel on mild steel	---	0.64	---	0.178
nickel on nickel	0.9	0.53	0.28	0.12
nylon on nylon	0.2	---	---	---
platinum on platinum	1.2	---	0.25	---
plexiglass on plexiglass	0.8	---	0.8	---
plexiglass on steel	0.45	---	0.45	---
polyethylene on steel	0.2	---	0.2	---
polystyrene on steel	0.325	---	0.325	---
polystyrene on polystyrene	0.5	---	0.5	---
silver on silver	1.4	---	0.55	---
steel on aluminum bronze	0.45	---	---	---
steel on brass	0.35	--	0.19	---
steel on cast iron	0.4	---	0.21	---
steel on copper alloy	0.22	---	0.16	0.145
steel on graphite	0.1	---	0.1	---
steel on phosphor bronze	0.35	---	---	---
Teflon on steel	0.04	---	0.04	0.04
Teflon on Teflon	0.04	---	0.04	0.04
zinc on cast iron	0.85	0.21	---	---
zinc on zinc	0.6	---	0.04	---
tin on cast iron	---	0.32	---	---

Typical manufacturer's data for load case-dependent friction coefficients:

Load case	Linear guide	Ball-type linear drive		Trapezoidal spindle		Sliding bearing sintered bronze / steel		Gliding bearing plastic / steel
Load case	µ¹⁾	µ¹⁾	η²⁾	µ¹⁾	η²⁾	µ¹⁾	η²⁾	µ¹⁾	η²⁾
Conveyor belt
Rack and pinion
Rotary table
Spindle	0.001 – 0.003	0.003	0.96	0.20	0.32
Crank gear	0.001 – 0.003					0.04 – 0.12		0.10 – 0.20
Winder

¹⁾Friction coefficient in µ and ²⁾efficiency in η