What Is The Best Grease For Ball Screws?

1. Core Requirements for Ball Screw Grease

Ball screws need grease to reduce friction prevent wear prevent corrosion and dissipate heat with key requirements as follows:

Excellent extreme pressure and anti-wear properties：This property can withstand the contact pressure between balls and screw raceways (which can reach hundreds of MPa) to prevent wear caused by direct metal-to-metal friction.

Suitable viscosity and viscosity-temperature characteristics：Low-viscosity base oils are needed to ensure fluidity in low-temperature environments (such as below -20°C) while high-viscosity base oils are needed in high-temperature environments (such as above 80°C) to prevent grease from thinning and .

Excellent oxidation stability：This property allows grease to resist oxidation and deterioration during long-term use (usually with a grease change interval of 1000-3000 hours) to prevent sludge from clogging raceways.

Excellent corrosion resistance：This property can resist moisture and dust in the environment to prevent rust on screws and balls (especially in humid or dusty industrial environments).

 

2. Optimal Grease Types for Different Scenarios

(1)General Industrial Scenarios (Room Temperature, Medium-to-Low Loads/Speeds)

Recommended Type：Lithium-Based Grease (such as ISO VG32-VG68 base oil with NLGI 2 consistency)

Suitable Applications：Ball screws of general machine tools and transmission mechanisms of automated equipment (operating temperature -10°C to 60°C speed ≤ 3000 rpm load ≤ 50% of rated dynamic load)

Advantages：High cost-effectiveness with balanced anti-wear and anti-oxidation properties suitable for most common working conditions such as lubrication of ball screws in CNC milling machines and linear actuators.

(2)High-Temperature, High-Load Applications (such as heavy-duty machine tools and metallurgical equipment)

Recommended Type：Polyurea Grease (PAO or synthetic ester base oil NLGI 2-3 consistency extreme pressure additive content ≥5%)

Suitable Applications：Ball screws with operating temperature -20°C to 120°C high load (≥70% of rated dynamic load) or high speed (3000-5000 rpm) such as those in transmission systems of heavy-duty lathes and forging equipment

Advantages：Excellent high-temperature resistance (no softening or loss after long-term use) strong extreme pressure and anti-wear properties ability to withstand high-frequency impact loads and reduced risk of raceway pitting.

(3)Low-Temperature Applications (e.g., cold chain equipment, outdoor low-temperature environments)

Recommended Type：Synthetic Lithium-Based Grease (low-viscosity PAO base oil NLGI 1-2 consistency pour point ≤ -40°C)

Suitable Applications：Ball screws operating at -40°C to 80°C such as those in automated cold storage handling equipment and outdoor photovoltaic tracking systems

Advantages：Good low-temperature fluidity and low starting resistance which prevents grease solidification at low temperatures from causing screw jamming or increased wear.

(4)Clean/Corrosion-Resistant Applications (e.g., semiconductor equipment, food processing machinery)

Recommended Type：Perfluoropolyether (PFPE) Grease or Food-Grade Silicone Grease

Suitable Applications：Ball screws in semiconductor wafer transfer mechanisms (requiring no oil mist contamination) and food packaging equipment (needing FDA certification)

Advantages：PFPE grease has strong chemical stability resistance to acid and alkali corrosion and no volatile contaminants; food-grade silicone grease is non-toxic and odorless suitable for food contact surfaces and has good corrosion resistance.

3. Selection Misconceptions and Precautions

Avoid blindly selecting high-viscosity grease：Excessively high viscosity increases the running resistance of ball screws leading to increased heat generation and energy consumption. Especially in high-speed scenarios (speed ＞5000 rpm) low-viscosity (ISO VG22-VG32) synthetic base oil grease should be preferred.

Do not mix different types of grease：For example mixing lithium-based grease with polyurea-based grease will damage the colloidal structure causing the grease to deteriorate and fail. Before changing grease thoroughly clean the residual old grease in the screw raceway.

Pay attention to the grease change interval and refill volume：Under normal working conditions change the grease every 1000-2000 hours of operation and the refill volume should fill 1/3-1/2 of the screw raceway gap. Excessive refilling will cause the grease to be squeezed out polluting the environment and wasting resources.