Lubricating greases can be defined as solid to semi-fluid products of the dispersion of a thickening agent in a liquid lubricant:
Commodity greases, usually based on lithium, calcium or sodium soaps (including some EP and lithium complex products) are general-purpose, low-cost products produced in large volumes.
High-specification greases, often based on a complex soap, are frequently manufactured with highly refined or synthetic base oils for more demanding applications than can be met with commodity grease products.
Today the performance of greases is described by norms such as DIN 51 502 in Europe and ISO. Ravensberger Schmierstoffvertrieb GmbH marks its greases according to DIN 51 502. RAVENOL greases are used for permanent lubrication of rolling and plain bearings, sliding surfaces, gears / tooth segments, belt automatics and hinges.
DIN 51 502 DESIGNATIONS for greases:
Grease application | |
K | for bearings and sliding surfaces according to DIN 51 825 |
G | for enclosed gears according DIN 51 826, OG – for open gears |
M | plain bearings and seals |
Base oils and additives | |
P | EP-additives |
F | solid additives (graphite, molybdenum disulfide, etc) |
E | polyester |
FK | perfluorochemical fluid |
HC | synthetic-hydrocarbons |
PH | phosphoric acid ester |
PG | polyglycol |
SI | silicon oil |
X | others |
MAX. TEMPERATURE AND WATER STABILITY
Additional class |
upper application – temperature |
Behaviour of greases in the presence of water according DIN 51 807 at a temp. of |
|
in °C | 40 °C | 90 °C | |
C | 60 | 0 or 1 | |
D | 60 | 2 or 3 | |
E | 80 | 0 or 1 | |
F | 80 | 2 or 3 | |
G | 100 | 0 or 1 | |
H | 100 | 2 or 3 | |
K | 120 | 0 or 1 | |
M | 120 | 2 or 3 | |
N | 140 | ||
P | 160 | ||
R | 180 | ||
S | 200 | ||
T | 220 | ||
U | over 220 |
1 – weakly washing-out
2 – average washing-out
3 – strong washing-out
Classifications of greases by NLGI numbers
NLGI-class | Appearance | worked penetration in 0,1 mm DIN ISO 2137 |
Application |
000 | fluid | 445 / 475 | Centralized grease system and gear greases |
00 | semi-fluid | 400 / 430 | |
0 | very soft | 355 / 385 | Greases for bearings |
1 | soft | 310 / 340 | |
2 | “normal” grease | 265 / 295 | |
3 | firm | 220 / 250 | |
4 | very firm | 175 / 205 | Block greases |
5 | hard | 130 / 160 | |
6 | very hard | 85 / 115 |
NLGI 00 and 000 – semi-fluids for centralized grease systems
NLGI 1 – used in winter
NLGI 2 – multi-purpose
NLGI 3 – used in summer