NTN Develops “Lubricating Unit for Grease Lubricated Bearings for Machine Tool Spindles”October 29, 2024
- Realizing long lubrication life of grease in high speed rotational conditions
- Achieving high speed rotational performance supporting dmn value of 1.9 million, the industry's highest level as grease lubricated bearings!
NTN Corporation (hereafter, NTN) has developed the “Lubricating Unit for Grease Lubricated Bearings for Machine Tool Spindles” that allows grease lubricated bearings to have longer operating life. Adopting this unit reduces the grease deterioration, which is an issue for grease lubricated bearings to rotate at high speed and enables grease lubricated bearings to be used in the high speed rotational condition of dmn value*1 of 1.9 million. We will facilitate the switch to grease lubrication from air-oil lubrication, which has been commonly used in high speed rotational conditions, contributing to saving energy and carbon neutrality of machine tools.
- An indicator that expresses the rotational performance of bearings and is multiplied bearing pitch circle diameter (mm) by rotational speed (min-1)
“Lubricating Unit for Grease Lubricated Bearingsfor Machine Tool Spindles”
Applied areas in machining center and main spindle(marked in red)
Background of development
The rotational speed of machine tool spindles is becoming increasingly higher to shorten machining times. Air-oil lubrication and grease lubrication are available as lubrication methods for bearings that support main spindles. Air-oil lubrication is generally used for application which needs high speed rotation performance exceeding dmn value of 1.4 million.
While air-oil lubrication can provide stable lubrication over a long period of time, it is difficult to achieve saving energy because it requires additional facilities regarding compressed air and air-oil supply. Since grease lubrication is performed with the grease initially filled in the bearing, it does not need other facilities. On the other hand, as the grease deteriorates due to the heat generated within the bearing, lubrication life tends to be shortened at high speed rotation.
Recently, efforts have been made to save more energy of machine tools in order to achieve carbon neutrality, and there is a growing need to apply grease lubricated bearings to high speed rotation conditions, where only air-oil lubricated bearings can be used.
Considering the situation, NTN has newly developed the unit product that can be used for a long period of time by reducing the grease deterioration in high speed rotational conditions to ensure lubricating durability.
About the developed product
This is a spacers unit that has our original lubrication mechanism in spacers adjoining the bearing for machine tool spindles. In addition to the lubrication mechanism, outer ring spacer and inner ring spacer are equipped with lubricating oil tank, sensor and processing circuit based on the sensor data, radio module, and stand-alone power supply. Since it generates power from the spindle rotation and provides the power to drive the electrical components, no external power supply is required, and operation can be performed independently.
Lubrication is carried out at preset time intervals based on the results of our basic tests and analysis of the mechanism of grease deterioration, which can extend the lubrication life of the grease. In the future, we will use built-in sensors to detect when the lubricant is depleted and supply the required quantity of lubricant at the optimum timing. This will further improve the operating life.
This product ensures the grease durability in high speed rotational conditions and enables the application of grease lubricated bearings under high speed rotational conditions of dmn value of 1.9 million.
Features
| 1. High speed rotational performance | dmn value of 1.9 million (the industry's highest level as grease lubricated bearings, 35% improvement compared to the conventional product) |
|---|---|
| 2. Long operating life |
Over 2.5 times longer lubricating life compared to the conventional product Aim at over 15 times through establishing technologies to supply oil at the optimum timing by sensor |
| 3. Wireless | Easy to assemble and handle with built-in sensors and power supply |
NTN will work to further improve this product through operational tests, aiming to bring it to market as soon as possible. At the same time, we will develop all the elements that make up bearings such as grease and retainer to improve high speed rotational performance of grease lubricated bearings, which is becoming increasingly required in the machine tool market.
NTN will exhibit this product at the “JIMTOF2024 The 32nd JAPAN INTERNATIONAL MACHINE TOOL FAIR” held in Tokyo Big Sight from November 5 to 10.
Applications
Machine tool spindles (machining centers, lathes, multi-function machines), etc.
Structure
Comparative result of continuous operation time (dmn value of 1.9 million)
Inquiries about this release
