What grease for high-speed bearings

Spindle bearings, also known as precision rolling bearings, are designed to handle very high RPMs, which is essential in applications such as CNC machines, drills, milling machines, and grinders. These types of bearings are optimized to minimize friction and increase machining accuracy. For this reason, lubrication of these bearings is a very important issue in their maintenance and operation.

Requirements for greases in high-speed spindle bearings

1. High load capacity : The grease must withstand the high loads typical of spindle bearings without losing viscosity or breaking down.
2. Thermal Stability : Because of the high speeds involved, the grease must have excellent thermal stability to resist degradation at elevated temperatures.
3. Low viscosity at high speeds : Lower viscosity is preferred to reduce friction and power losses while providing adequate lubricating film thickness.
4. Contamination resistance : The grease should be resistant to emulsification and degradation in the presence of water, coolants and metal particles.
5. Compatibility with Machine Materials : The grease should not corrode or react negatively with materials used in spindle bearings and adjacent components.

Spindle Bearing Speed ​​Range as an Important Factor in Grease Selection

The speed range that spindle bearings can handle depends on several factors, such as:

1. Bearing type : For example, angular contact ball bearings and roller bearings can handle different rotational speeds due to their design and the way they handle loads.
2. Bearing size and geometry : Larger bearings typically handle lower rotational speeds, while smaller bearings are capable of operating at higher speeds.
3. Lubrication : The type and method of lubrication (oil, grease, oil mist) have a significant influence on the maximum rotational speeds that a bearing can withstand. Oil lubrication systems are often used at very high speeds.
4. Cooling : Spindle bearings often require cooling systems, especially at high rotational speeds, to prevent overheating and damage.

Example values ​​of rotational speed

For angular contact ball bearings, which are commonly used in machine tool spindles, typical maximum speeds can range from 12,000 to 30,000 RPM (revolutions per minute), and in specially designed systems with high quality lubrication and cooling, speeds can be even higher, as in the case of turbine bearings or high-performance grinding machines, speeds can reach 100,000 RPM or more. To determine the exact allowable speeds of a bearing, it is best to check the manufacturer's technical specifications or consult their technical department. For this reason, many manufacturers of high-speed bearings specify the lubricants they prefer for a given bearing.

Types of Synthetic Greases for High-Speed ​​Bearings

Synthetic greases are the best choice for high-speed bearings because they provide excellent protection and stability under extreme conditions. The most commonly used types include:

1. Synthetic Polyester (POE) Lubricants
• Excellent thermal and oxidation stability.
• Low viscosity while maintaining high lubrication properties.
• Ideal for applications in machine tools and medical devices.
2. Synthetic greases based on polyalphaolefins (PAO)
• High resistance to aging and oxidation.
• Good compatibility with elastomers and seals.
• Often used in the aviation industry.
3. Synthetic silicone-based lubricants
• Excellent resistance to extreme temperatures.
• Used in applications where large changes in ambient temperature occur.
4. Fluoropolymer greases
• Exceptional resistance to chemicals and temperatures.
• High stability even at extreme speeds.
5. Mixed greases

o Synthetic greases with various base-thickener combinations, e.g. polyester on ester oil.

Selecting grease for different types of high-speed bearings

Single row bearings

For single-row bearings, very low viscosity greases that minimize frictional resistance are best. The best choice will be greases based on POE or PAO, which provide low heat emission even at very high speeds.

Double row bearings

In the case of double-row bearings, which operate under greater loads, it is worth using greases with a slightly higher viscosity, but still based on synthetic bases. The addition of friction modifiers allows maintaining optimal working conditions.

Single row double direction bearings

These bearings require greases with high thermal stability that effectively reduce friction over a wide temperature range. Fluoropolymer greases may be the best solution here, especially in applications with large load fluctuations.

The most common mistakes when selecting grease

1. Choosing a grease with too high viscosity
• This causes the temperature to increase and the bearing to wear out faster.
2. Using mineral lubricants
• Mineral greases do not provide adequate protection at extreme rotational speeds.
3. No consideration for application specifics
• Each type of bearing requires an individual approach to lubricant selection.

The Role of Grease in Bearing Life

Selecting the right grease for high-speed bearings, including spindle bearings, requires understanding the specifics of their operation and the conditions in which they will be used. Synthetic greases based on POE, PAO, silicone or fluoropolymers are the best solution for these applications, providing long-term protection and optimal performance. However, it is crucial to precisely match the grease to the type of bearing and operating conditions to minimize the risk of overheating and extend the life of the device. Due to the complexity of selecting grease for high-speed bearings, it is best to entrust this task to specialists who have extensive experience and access to many greases from several manufacturers.

The ABS Serwis company, which has been a supplier of lubricants for industry for many years, offers us several products in its store that meet all the requirements for a grease for high-speed bearings, but also offers the possibility of selecting such a grease as part of the questions asked in the store.