Page 103 - Mechanical Engineer's Data Handbook

92 MECHANICAL ENGINEER'S DATA HANDBOOK

2.9.3 Bearing materials

Metals
Brinell Thin shaft Load capacity, p Maximum
Material hardness hardness (MPa) temperature ("C)
Tin base babbitt 20-30 < 150 5.5-10.3 150
Lead base babbitt 15-20 < 150 5.5-8 .O 150
Alkali-hardened lead 22-26 200-250 8.0-10.3 260
Cadmium base 3WO 200-250 10.3-15 260
Copper lead 20-30 200 10.3-16.5 175
Tin bronze 60-80 300-400 2 30 260
Lead bronze 40-70 300 20-30 225
Aluminium alloy 45-50 200-300 2 30 125
Silver plus overlay 25 3w00 2 30 260

Porous metals and nonmetals
Load Maximum Maximum
capacity, p temperature velocity, u Maximum pu
Materials (MPa) ("C) (ms-') (MPaxm s-')

Porous metals 30 75 7.5 0.7
Rubber 0.35 75 5 .O 0.525
Graphite materials 4 350 12.5 5.25 wet, 0.525 dry
Phenolics 35 95 12.5 0.525
Nylon 7 95 2.5 0.875
Teflon 3.5 265 1.2 0.35

2.9.4 Surface finish and clearance for
bearings

Surface
Diametral clearance
Type of service Journal Bearing (mm)

Precision spindles Hardened ground
ND < 50 x lo3 steel Lapped 0.01750 +0.0075
Precision spindles Hardened ground
ND>50x lo3 steel Lapped 0.020 + 0.01
Electric motors, generators, etc. Ground Broached or reamed 0.020 + 0.01 5
General machinery, continuous
running Turned Bored or reamed 0.0250 + 0.025
Rough service machinery Turned 1.5-3 pm 0.0750+0.1

N =revolutions per minute, D= diameter (mm).