Grease Selection and Compatibility Advisor

1. Select the application and enter maximum continuous speed in rpm and bearing mean diameter in mm. If only bore and outside diameter are known, use their arithmetic mean.
2. Select load severity, grease operating-temperature limits, water exposure, orientation, and relubrication method.
3. Enable the food-contact requirement only when NSF H1 registration is mandatory.
4. Select current and candidate thickener/base-oil families. Use “No current grease” only for an actually clean initial fill; otherwise select “Unknown” when documentation is absent.
5. Choose Calculate to update the screen. Choose Reset to restore the worked example.
6. Use the NLGI result as an initial consistency range, then verify viscosity, additives, pumpability, temperature life, elastomers, fill quantity, and relubrication interval with OEM and supplier data.
7. For Conditional, High, or Unresolved compatibility, do not direct top-up. Follow the purge/cleaning action and test the actual mixture.
8. Do not use this model as final product approval, a bearing-life or relubrication-interval calculation, food-safety certification, or a substitute for OEM instructions and representative mixture testing.

dₘ = (d + D) / 2, where d is bearing bore and D is outside diameter in mm. This interface accepts dₘ directly.

S = n × dₘ, where n is maximum continuous speed in rpm and S is in mm·rpm.

G = clamp(2 + Δspeed + Δorientation + Δrelubrication, 0, 3). Speed adjustment is +0.5 at S ≤ 50,000; 0 from above 50,000 to below 300,000; −0.5 from 300,000 to below 500,000; and −1 at or above 500,000. Vertical orientation adds +0.5. Automatic delivery subtracts 0.5. Half-steps display as the bounding adjacent NLGI grades. This is a disclosed screening rule, not a standard or OEM selection equation.

R = max(Rthickener, Rbase oil), with 0 = Low, 1 = Conditional, 2 = High, and 3 = Unresolved. The mappings are evaluated in the order shown. Rthickener = 0 for a clean initial fill (current thickener is “none”, including when the candidate family is unknown), identical known families, or lithium/lithium-complex. It is 3 when either family is unknown after the clean-fill exception; 2 for clay/polyurea, aluminum-complex/polyurea, and calcium-sulfonate/clay; Conditional (1) is the fallback for every other unlike known thickener pair. Rbase oil = 0 for a clean initial fill (current base oil is “none”, including when the candidate family is unknown), identical known families, or mineral/PAO. It is 3 when either family is unknown after the clean-fill exception; 2 whenever unlike listed families include PAG or silicone; Conditional (1) is the fallback for every other unlike known base-oil pair.

Temperatures use °C and must satisfy Tmin < Tmax. They are grease operating temperatures, not ambient temperatures.

This screening assumes positive speed and diameter and correctly identified chemistry. Family names cannot prove compatibility. Actual-product mixture testing takes precedence.

• ASTM D217 and ISO 2137: worked penetration and consistency classification.
• ASTM D6185: evaluation of binary grease-mixture compatibility.
• DIN 51825: lubricating-grease classification context. NSF H1 is a procurement constraint, not proof of tribological suitability.
• SKF LubeSelect and SKF Grease Compatibility: operating-condition and changeover workflow background.

Compatibility can also depend on additive systems, concentrations, elastomers, contamination, ageing, and mixing ratio. Confirm product-specific operating limits and test representative mixtures before changeover.