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Bearing Grease Speed Factor Planning Guide

Check grease compatibility with bearing speed and temperature, get regreasing interval estimates

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Bearing lubrication kit

Greasing tools and consumables for bearing speed and interval decisions:

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Free bearing lubrication planning guide that screens grease speed and temperature suitability with ndm speed factor, base oil viscosity, NLGI consistency grade, and operating temperature context. The result is a preliminary review signal, not a product approval or manufacturer-certified relubrication interval. Verify the grease data sheet, bearing catalog, seals, housing, purge path, contamination, duty cycle, and OEM instructions before changing routes or CMMS records.

Pro Tip: Temperature is a major grease-life driver. SKF-style guidance commonly checks interval reduction above 70°C (158°F), but the approved response depends on the grease product, bearing design, housing airflow, measured bearing temperature, load, speed, and contamination. Short intervals should trigger a heat and reliability review, not only a switch to a more expensive grease.

How It Works

  1. Enter Bearing Information

    Input the bearing bore and pitch diameter in millimeters, bearing type, and operating speed in RPM. The calculator computes the ndm speed factor to evaluate against the grease speed limit.

  2. Select Grease Properties

    Choose the NLGI grade (1, 2, or 3) and base oil viscosity class. NLGI 2 is the most common general-purpose grade. Higher-viscosity base oils are better for slow, heavy-load applications. Lower-viscosity oils are needed for high-speed bearings.

  3. Enter Operating Temperature

    Input the bearing operating temperature. The calculator checks against the grease dropping point and base oil oxidation limits. Temperature above 70°C starts reducing grease life significantly.

  4. Select Environment Factors

    Indicate the contamination level (clean, moderate, or severe) and bearing orientation (horizontal or vertical). Vertical shafts require more frequent regreasing because grease migrates away from the contact zone under gravity.

  5. Review the Screening Result

    Review the preliminary grease suitability signal and estimated interval warnings. Confirm the result with product data, OEM instructions, condition monitoring, and site reliability review before changing maintenance instructions.

Built For

  • Maintenance teams setting up lubrication schedules for plant equipment
  • Reliability engineers evaluating grease selection for high-speed or high-temperature bearings
  • Millwrights determining regreasing intervals after bearing replacements
  • Plant managers standardizing lubrication practices across multiple machines
  • Lubrication technicians verifying that specified grease is appropriate for operating conditions

Assumptions

  • Relubrication screening rows draw on general SKF/Schaeffler-style guidance and must be checked against current manufacturer data.
  • Bearing operating temperature is within the grease base oil and thickener working range.
  • Bearing seals or shields are intact and providing the expected level of contamination protection.
  • Grease gun delivery volume is known (typically 1-1.5 grams per pump stroke for a standard grease gun).

Limitations

  • Does not account for specific grease formulations (polyurea, lithium complex, PFPE) that have different relubrication characteristics.
  • Sealed bearings (2RS, 2Z) with lifetime grease fill are not candidates for relubrication and are excluded.
  • Vertical shaft applications, high-vibration environments, and washdown conditions require shorter intervals not calculated here.
  • Automatic lubrication system (single-point or centralized) dispensing rates are not sized by this tool.

References

  1. SKF Maintenance Handbook - Bearing Lubrication: Relubrication Intervals and Grease Quantities
  2. FAG/Schaeffler - Rolling Bearing Lubrication (WL 81 115 technical publication)
  3. NLGI Lubricating Grease Guide - Grease Selection and Application
  4. ISO 12924 - Lubricants, Industrial Oils, and Related Products: Family L, Greases

Frequently Asked Questions

NLGI 2 is the default for most industrial bearing applications. It stays in the bearing without leaking in horizontal applications and provides adequate lubrication across a wide speed and temperature range. NLGI 1 (softer) is better for cold environments, low-speed applications, and centralized lubrication systems. NLGI 3 (firmer) is better for vertical shafts and high-temperature applications where softer grease would run out.
Start with bearing, speed, temperature, load, contamination, grease, housing, and OEM guidance, then compare the screening interval with site history and condition-monitoring data. Some plants use qualified ultrasonic lubrication procedures, but the method, baseline, route, and technician training must be controlled.
Generally no. Mixing greases with different thickener types (lithium with polyurea, for example) can cause the mixture to soften, harden, or separate, leading to lubrication failure. If you must change grease types, purge the old grease completely by running the bearing with the new grease and flushing through until only new grease exits.
Excess grease in the bearing cavity gets churned by the rolling elements, generating friction heat. This heat breaks down the grease, raises the bearing temperature, and can cause seal failure. The correct fill level is one-third to one-half of the bearing free space. More is not better.
Disclaimer: Grease suitability and regreasing intervals are screening estimates. Actual limits depend on grease formulation, base oil, thickener, additives, bearing series, precision class, seals, housing, purge path, load, speed, temperature, contamination, duty cycle, and OEM instructions. Follow the bearing and grease manufacturer recommendations for the specific application.