Page 97 - Mechanical Engineer's Data Handbook

86 MECHANICAL ENGINEER’S DATA HANDBOOK

Clutches and brakes (continued)

Coefficient of friction Maximum Maximum
temperature pressure
Materials Wet Dry (O°C) (bar)

Powder metal/chrome plated 0.05-0.1 0.1-0.3 500 20
hard steel
Wood/cast iron or steel 0.16 0.2-0.35 150 6
Leather/cast iron or steel 0.12-0.15 0.3-0.5 100 2.5
Cork/cast iron or steel 0.15-0.25 0.3-0.5 100 1
Felt/cast iron or steel 0.18 0.22 140 0.6
Vulcanized paper or fibre/ 0.3-0.5 100 3
cast iron or steel
Woven asbestos/cast iron 0.1-0.2 0.3-0.6 250 7-14
or steel
Moulded asbestos/cast iron 0.08-0.12 0.2-0.5 250 1
or steel
Impregnated asbestos/cast iron 0.12 0.32 350 10
or steel
Asbestos in rubber/cast iron 0.3-0.40 100 6
or steel
Carbon graphite/steel 0.05-0.1 0.25 500 20
Moulded phenolic plastic with 0.1-0.1 5 0.25 150 7
cloth base/cast iron or steel

Band brake materials

Material Lubrication Coefficient of friction
Leather belt/wood Well lubricated 0.47
Leather belt/cast iron Well lubricated 0.12
Leather belt/cast iron Slightly lubricated 0.28
Leather belt/cast iron Very slightly lubricated 0.38
Steel band/cast iron Dry 0.18

Machine tool slii Rubber - sliding
~ ~
Pressure (bars) Surface Wet Dry
Materials 0.5 1.0 1.5 2.0 4.0 Asphalt 0.254.75 0.50-0.80
Concrete 0.45-0.75 0.60-0.85
Cast iron/cast iron 0.15 0.20 0.20 0.25 0.30
Cast iron/steel 0.15 0.20 0.25 0.30 0.35
Steel/steel 0.15 0.25 0.30 0.35 0.40