Page 291 - Cam Design Handbook

THB9 9/19/03 7:26 PM Page 279

CAM MATERIALS AND LUBRICATION 279

TABLE 9.8
Mineral Oil Classification and Comparative Viscosities

Temperature
38°C (100°F) 99°C (210°F)
Category SAE ASTM AGMA
number grade* gear oil Approximate viscosity, cSt
— 32 — 2 —
— 40— 3 to 5.5 —
— 60— 8.5 to 12 —
— 75 — 12 to 16 —
— 105 — 19 to 24 —
— 150— 29 to 35 —
Extra light — 215 — 42 to 51 —
10W — 1 45 4.2
— 315 — 61 to 75 —
Light 20W — 2 69 5.7
— 465 — 90 to 110 —
Medium 30W — — — 10
— — 3 128 —
— 700 — 130 to 166 —
Medium heavy 40— — — 13
— — 4 183 —
Heavy 50— — — 17
— 1000 — 194 to 237 18
— — 5 — —
— 1500 — 291 to 356 —
— 2150— 417 to 525 —
— — 6 — 24
140— — — 25
— 3150— 630 to 780 —
Super heavy — — 7 † — 29
— 4650— 910 to 1120 —
— — 8 † — 36
250— — — 43
— — 8A † — 47
— 7000 — 1370 to 1670 —
— — 9 — 97
— — 10— 227
— — 11 — 464
*Grade number is equivalent to average Saybolt universal viscosity (SUV) at 38°C (100°F).
†
Compounded with fatty oil.

and may be formed by the chemical reaction of sulfur or from the chemisorption of iron
stearate. Figure 9.12 shows the range of film thicknesses for various types of films
(Godfrey, 1968). The films can provide separation of the metal surfaces when the lubri-
cant becomes thin enough for the asperities to interact. The boundary film prevents contact
of the asperities and at the same time provides low shear-strength properties that prevent
shearing of the metal and reduce the friction coefficient over that of the base metal. These
boundary films provide lubrication at different temperature conditions, depending on the