Lubricants: The Underestimated Key to Success for Your Precision Gearbox

Lubricants are an integral part of precision gearboxes and have a significant impact on performance, service life, smooth operation, and operational reliability. For the gearbox to reach its full performance potential, the lubricant must be precisely matched to the application, load profile, and design characteristics of the drive unit. Otherwise, there is a risk of increased wear, premature failures, and reduced performance—for example, due to lower efficiency.

Lubricants for Precision Gears

Precision gearboxes place increased demands on lubrication, as they operate with tight tolerances, high contact pressures, and very thin lubricant films. Added to this are high power densities, which lead to severe thermal and mechanical stresses. 

Strain wave gears and cycloidal gears use comparable basic principles of lubrication but differ in their specific characteristics. For example, strain wave gears have two load zones: the bearings (high- and low-speed) and the gear teeth area. Both zones have tight tolerances and require specific lubricant properties. Cycloidal gearboxes have a large number of bearings (typically 14) as well as a complex, finely detailed design, which makes reliably supplying all contact points with lubricant a tribological challenge. This must be taken into account when selecting the lubricant.

What factors influence the choice of lubricant?

Two factors are relevant when selecting a lubricant: the internal loads on the gear (e.g., pressure and shear loads) and the specific requirements of the application (including dynamics and operating conditions). Key properties include the lubricant’s temperature behavior across the entire operating range, its thermal conductivity, viscosity and its stability under operating and load conditions, shear stability, and flow behavior within the system.

Particularly high demands arise at very high rotational speeds (centrifugal forces can displace lubricants), during quasi-static movements (insufficient mixing occurs), and in extreme temperature ranges—especially at low temperatures—where viscosity and flow behavior become critical.

Key factors influencing lubricant selection:

• Operating temperature
• Rotational speed
• Load level
• Application dynamics
• Service life requirements
• Operating environment

What are the advantages of lubricants supplied directly by the gear manufacturer?

Lubricants from the gear manufacturer are perfectly matched to the specific precision gear and its characteristics. They are tested within the entire system and enable a reliable assessment of service life. In addition, they are designed for maximum gear performance and reduce the risk of wear and premature failures.

Third-party lubricants are generally not specifically tailored to the respective gear unit and have not undergone gear-specific approval testing. Depending on the application, this can lead to varying wear behavior and performance losses. In cycloidal gearboxes, for example, the use of non-approved lubricants can reduce the nominal service life from 6,000 to 4,000 operating hours.

Comparison: Lubricants from the Gearbox Manufacturer vs. Third-Party Products

Lubricant as a Key Factor

In summary, it can be stated that the lubricant is a key factor influencing the performance and service life of precision gearboxes. Precise matching to the load, temperature, and dynamics of the specific application is crucial. An example from robotics illustrates the importance of this application-specific design: Even with identical robot models and the same drives, different lubricants may be required depending on the application—for example, in welding, in low-temperature handling, or in food and beverage applications. 

High-Performance Lubricants from Nabtesco

As the Nabtesco Group, we draw on extensive experience and deep expertise across a wide range of applications to develop high-performance lubricants that are perfectly matched to our precision gearboxes and their characteristics. The strain wave gears and cycloidal gears are lubricated for life and offer effective wear protection for a long service life and maximum precision.

Due to the high contact pressure in cycloidal gears (between the cam discs and rollers) and strain wave gears (between the flex spline and circular spline teeth), we use special additives. Molybdenum has proven effective in cycloidal gearboxes, as it offers good friction properties and functions reliably even under high pressure loads. In spline gearboxes, additives can also help optimize acoustic performance.

Learn about our lubricants and their benefits

Would you like to learn more about our precision gears and lubricants? Our experts will be happy to advise you. Contact us now!