Machinery's Handbook, 31st Edition
Selecting Lubricants 2513 optimal lubricant choice for each specific application. Table 14 offers general guidelines for lubricant choice when operating conditions are known, and Fig. 11 offers lubricant vis- cosity guideline choices based on bearing speed in rpm. Once the initial lubricant choice is made, its viscosity must be checked against the specific operating temperature to ensure that the lubricant is suitable for speed, load, and temperature conditions. Table 14. General Guidelines for Choosing a Preferred Lubricant Type Condition Oil Grease Solid Clearances Designed for Oil d d Clearances Designed for Grease d d High Speed, Low Load d Low Speed, High Load d Low Speed, Oscillating Load d d High Temperature d d a Full Film Applications d d Boundary Layer Applications d d Contaminated Working Environment d Product Cannot Tolerate Leaks d d Closed Gearbox d Isolated Bearings d a Automated delivery system.
Boundary and Mixed-film Lubrication Heavy Load
Grease
ISO 320
SAE 50
ISO 220
SAE 40
ISO 100
Full-film Lubrication Heavy Load 250
SAE 30
ISO 46 ISO 68
SAE 10 SAE 20
ISO 32 ISO 15 ISO 10
SAE 5
2000 6000
10
20
40 60 100 200 40 60
10,000
100
4000
Journal Speed, N (rpm)
Fig. 11. Lubricant Viscosity Selection Guide based on Bearing Speed in rpm
Lubricant additives deliver different working characteristics to the lubricant. Knowing and documenting a machine or system’s lubricant application requirements will facilitate a consolidation of lubricant requirements and assist in determining the optimal lubricant additive package. Table 15 reviews typical lubricated components, and assigns priority guideline ratings against a number of important lubricant functional attributes. This information is a starting point when working with the lubricant manufacturer to enable consolidation of lubricant needs and choose lubricants with suitable additives.
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