The Coefficient of Friction

Materials and Material Combinations	Coefficient of Friction
Materials and Material Combinations	Clean	Lubricated
Steel	0.74	0.16
Copper-lead alloy	0.22	-
Phosphor-bronze	0.35	-
Aluminum-bronze	0.45	-
Brass	0.35	0.19
Cast iron	0.4	0.21
Bronze	-	0.16
Sintered bronze	-	0.13
Hard carbon	0.14	0.11-0.14
Graphite	0.1	0.1
Tungsten carbide	0.4-0.6	0.1-0.2
Plexiglas	0.4-0.5	0.4-0.5
Polystyrene	0.3-0.35	0.3-0.35
Polythene	0.2	0.2
Teflon	0.04	0.04
Aluminum-aluminum	1.35	0.3
Cadmium-cadmium	0.5	0.05
Chromium-chromium	0.41	0.34
Copper-copper	1	0.08
Iron-iron	1	0.15-0.20
Magnesium-magnesium	0.6	0.08
Nickel-nickel	0.7	0.28
Platinum-platinum	1.2	0.25
Silver-silver	1.4	0.55
Zinc-zinc	0.6	0.04
Glass-glass	0.9-1.0	0.1-0.6
Glass-metal	0.5-0.7	0.2-0.3
Diamond-diamond	0.1	0.05-0.1
Diamond-metal	0.1-0.15	0.1
Sapphire-sapphire	0.2	0.2
Hard carbon on carbon	0.16	0.12-0.14
Graphite-graphite (in vacuum)	0.5-0.8	-
Graphite-graphite	0.1	0.1
Tungsten carbide-tungsten carbide	0.2-0.25	0.12
Plexiglas-plexiglas	0.8	0.8
Polystyrene-polystyrene	0.5	0.5
Teflon-Teflon	0.04	0.04
Nylon-nylon	0.15-0.25	-
Solids on rubber	1-4	-
Wood on wood (clean)	0.25-0.5	-
Wood on wood (wet)	0.2	-
Wood on metals (clean)	0.2-0.6	-
Wood on metals (wet)	0.2	-
Brick on wood	0.6	-
Leather on wood	0.3-0.4	-
Leather on metal (clean)	0.6	-
Leather on metal (wet)	0.4	-
Leather on metal (greasy)	0.2	-
Brake material on cast iron	0.4	-
Brake material on cast iron (wet)	0.2	-

Reduce Friction, Extend Tool Life

Coated carbide inserts and end mills lower the effective coefficient of friction at the cutting edge, reducing heat buildup and tool wear.

Match the tool to the material

Knowing how a material behaves is half the job. The other half is a grade and geometry built for it.