Machinery's Handbook, 31st Edition
2510
TEMPERATURE EFFECTS
10 15 20 30 50 10 20 100 10,000
3 4 5
-30-20-10 0 10 20 30 40 50 60 70 80 90 10 11 12 13 Temperature °C Fig. 7. Temperature Effect on Viscosity for Different Oils
Temperature affects not only the viscosity of the oil, it affects the condition and life expectancy of the oil as shown in Fig. 8. For every 17 ° F (10 ° C) increase in temperature, oxidation rates double and effective oil life is halved. Operating temperature is the lead- ing indicator in determining oil change out frequencies
300
250
Synthetic Oil (Esters and Silicones)
200
180
160
150
130
100
100
Mineral Oil (Anti-oxidant Additive)
75
50
0
1
10
100
1000
10,000
Oil Life (Hours)
Fig. 8. Expected Oil Life at Varying Operating Temperatures. Oxidation is the leading cause of lubricant failure. Fig. 9 shows typical upper and lower working limits for various lubricating oils. Lubricating Grease.— In situations where the containment and continued application of lubricating oil is not practical, lubricating grease is widely used—most specifically in rolling element bearings requiring only periodic lubrication, and slow-speed, high-load boundary lubrication applications. Easier to retain than oil, grease offers lower lubricant losses and good sealing qualities. When utilized in an automatic delivery system, grease can provide full film lubrication. Grease is a blended mix of the lubricating oil (mineral or synthetic—usually di-ester or silicone based), oil additive package, and fatty acids mixed with metallic alkaline soap
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