Gears

Gearbox designs aim to increase efficiency by improving power transfer while minimizing noise and heat generation. Plastic housings and gears made of high-performance polymers are enabling lighter and more compact designs whereas metal gears are often used in applications operating under high temperatures and loads. When properly selected, grease can improve the performance and service life of gearboxes by reducing friction and wear, starting and running torque, noise and vibration, and operating temperatures.

Advantages of Lubricating Gears

Nye offers lubricants for a wide range of gears including planetary, spur, helical, worm, spiral bevel, and hypoid gears. Protecting your gears with grease is key to preventing common causes of failure including metal pitting and corrosion as well as tooth breakage. Our specialty lubricants improve gear performance and:

  • Prevent Friction & Wear
  • Protect Against Corrosion & Oxidation
  • Reduce Noise & Heat Generation
  • Extend Component Service Life
  • Shield Against Dust & Debris

 

What to Consider When Selecting a Gear Oil or Grease

Contamination, oxidation, and incompatible materials are all reasons why a lubricant may form sludge or varnish. Therefore, selecting a lubricant formulated with your operating conditions in mind is key. These factors should be considered when selecting a gear lubricant:

Oils may be used in stationary, closed gearbox applications where relubrication is difficult and forced circulation is present. Oils can easily circulate through the gearbox to provide constant lubrication. However, many devices, such as those that are mobile or utilize unique gearbox orientations, cannot utilize an oil bath to remove heat and wear debris. In these applications oils are often replaced with specialty synthetic greases to reduce component cost by eliminating the need for closed and sealed gear boxes. Grease is also the preferred solution for applications requiring long-lasting lubrication or as we like to call it, “Lube for Life.” – gears that are only lubricated once for the entire lifetime of their assembly.

Elevated speeds and loads increase temperature, which can degrade the lubricant and ultimately the performance of the gear train. The use of Anti-Wear, Anti-Corrosion, and Extreme Pressure (EP) additives in Nye gear greases provides extra protection under these harsh conditions.

Nye’s EP additives contain inactive sulfur that prevents the corrosive attack of the gear surface without etching or softening yellow metals. Inactive sulfur forms a protective chemical layer on the metal surface which minimizes the potential of severe wear and welding. Lubricants with EP additives have greater film strength to reduce friction, protect your gear from wear, and prevent shock loading.  

Many designs use a combination of plastic and metal components within the gear assembly. It is important to select a lubricant that is compatible with all the materials in your assembly as incompatible materials can negatively impact the performance and integrity of your design.

Certain base oils and additives will absorb into plastic components and cause them to swell. Conversely, there are also oils and additives that extract soluble materials from some plastic components, causing them to shrink. Chemical interactions between certain base oils, additives, and plastics can affect the components’ molecular structure and may lead to embrittlement and other losses in mechanical performance. Lubricants with an ester base oil, while a great choice for metal gears, should be approached with caution as they have been known to negatively affect many plastics and elastomers.

Gears made of sintered and powdered metal are already impregnated with oils. To lubricate these gears it is important to select a grease with a base oil that is compatible with the oil already impregnated into the metal. This helps ensure that there is sufficient oil to lubricate the gear teeth.

With so many different materials and types of metals, plastics and elastomers that the gears, housings and seals can be made of, compatibility testing is always recommended to ensure a grease or oil will work properly in a specific application.

Operating temperature range plays a major role in determining whether a petroleum-based grease can be used or a synthetic lubricant is required. Synthetic lubricants tend to perform better at wider temperature ranges than petroleum products. They can help improve gearbox operation at high and low temperatures by reducing low temperature torque and reducing frictional heat. Careful consideration must be taken to ensure the lubricant can provide protection across the entire operating temperature range.

A lubricant that is too viscous at low temperatures cannot adequately move around the gearbox to lubricate the gear teeth. If a lubricant cannot withstand high temperatures, it will oxidize and leave behind unwanted by-products such as acids. These acids attack the metal surface and lead to increased wear and corrosion of the gear. Perfluoropolyether (PFPE) lubricants from our Uniflor™ product line provide a wide operating temperature range from -45 to 250 °C and are ideal for applications that operate at high temperatures and low loads.

Gears that need to perform under harsh environmental conditions, are exposed to chemicals, or operate under vacuum require special consideration when selecting a grease. Grease provides a seal against dirt and debris in open gearing applications. Many of our lubricants are also hydrophobic which keeps water away from the gear surface to prevent rust. Antioxidants and anti-corrosion additives can be added for additional protection against moisture and oxidation. For gears in vacuum applications, such as those found in Space or Semiconductor applications, we recommend PFPE or MAC chemistries with low outgassing and wide temperature capabilities. If your gear is being used in a medical application, we recommend selecting a lubricant from our NyeMed® biocompatible product line.

Gear Lubricants from Nye

The chemical homogeneity of synthetic lubricants results in greater load carrying capacity, higher viscosity indexes, better lubricity, greater efficiency and extended serviceability than petroleum-based oils and greases. Nye offers gear lubricants with protective additives in a variety of base oil chemistries.

Grease Base Oil Temp
Range (°C)
Kinematic
Viscosity
@ 40 °C
NLGI
Grade
/ Consistency
Type
PAO/Ester -20 to
150 °C
440 cSt 2
Medium
General Purpose Gear Grease
PAO/Polybutene -20 to
125 °C
291 cSt 1
Medium/Soft
General Purpose Gear Grease
PAO -30 to
125 °C
182 cSt 0
Semi-fluid
General Purpose Gear Grease
PAO -50 to
125 °C
40.7 cSt 2
Medium
General Purpose Gear Grease
PAO -20 to
125 °C
259 cSt 2
Medium
General Purpose Gear Grease
PAO -40 to
120 °C
243 cSt 0.5
Very Soft
General Purpose Gear Grease
PAO -40 to
125 °C
45 cSt 1
Soft
General Purpose Gear Grease
PAO/Ester -50 to
130 °C
37 cSt 1
Soft
General Purpose Gear Grease
PAO -40 to
125 °C
80.6 cSt 0.5
Very Soft
General Purpose Gear Grease
Phenylmethyl Silicone -50 to
200 °C
151 cSt - General Purpose Gear Grease
PFPE -50 to
225 °C
65 cSt 2
Medium
High Temperature Gear Greases
PFPE -40 to
225 °C
230 cSt 2
Medium
High Temperature Gear Greases
PFPE -20 to
260 °C
495 cSt 2
Medium
Food Grade Gear Grease
PFPE -70 to
250 °C
310 cSt 2
Medium
Food Grade Gear Grease
PAO -35 to
120 °C
194 cSt 2
Medium
Food Grade Gear Grease

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