In recent years, harmonic reducers have become a familiar term to anyone working in the industrial robot field. For many years, this core robot component, sometimes no bigger than the palm of your hand, has accounted for about 30% of the overall cost of a robot due to the long-term monopoly of core technologies by foreign brands. This reality has objectively driven up the cost of robot applications in China...
The Past and Present of Harmonic Reducers:
In the mid-1950s, with the development of global science and technology, American Mather, based on the theory of elastic deformation of thin shells, invented a new type of harmonic drive technology by applying the principles of flexibility and elasticity of metals. Harmonic drive technology is mainly used in aerospace, industrial robots, precision equipment and instruments, radar communication equipment, printing machinery, textile machinery, semiconductor wafer transfer devices, printing and packaging machinery, medical devices, metal forming machinery, instruments and meters, optical manufacturing instruments, nuclear facilities, and aerodynamic experimental research.
Six-axis industrial robot structure diagram
The emergence of harmonic drive technology attracted attention from various countries. Introduced to Japan in 1970, it led to the establishment of Japan's first leading company in integrated motion control – Harmonic Drive Systems Inc. (HDSI). HDSI's Harmonic Drive harmonic reducers are characterized by their lightweight, compact size, high transmission efficiency, wide reduction range, and high precision, and are widely used in various transmission systems. HDSI primarily manufactures and sells various precision reduction devices, making it a true leader in integrated motion control. To cover the low reduction ratio range that harmonic reducers cannot reach, HDSI has also developed the Harmonic Planetary precision planetary gear reducer. Its unique internal gear ring deformation process allows for tighter meshing of the planetary gears and eliminates backlash, thereby controlling transmission errors within a precise range. HDSI initially focused on domestic development, maintaining long-term cooperative relationships with companies such as Yaskawa Electric, Mitsubishi Electric, and FANUC.
In recent years, China's industrial robot industry has entered a new historical period of opportunity. International robot companies, represented by ABB, KUKA, Yaskawa, and FANUC, have entered China in large numbers, establishing factories and seizing market share. In China, industries such as mobile phone manufacturing, semiconductors, and LCD production machinery are experiencing increasingly strong demand for small robots. However, domestic industrial robots, especially components like harmonic reducers, servo motors, and control systems, still heavily rely on imports. This results in a gap in competitiveness compared to foreign companies, even though these are upstream and key components of industrial robots. According to statistics from the International Federation of Robotics (IFR), China imported approximately 22,000 industrial robots in 2012, making China the fastest-growing industrial robot market globally. HDSI's harmonic reducers are irreplaceable components in small industrial robots (under 20kg) or articulated arms, providing a new opportunity for its expansion into the Chinese mainland market. In January 2011, HDSI established Harmonic Drive (Shanghai) Trading Co., Ltd., a wholly-owned sales subsidiary in China. Primarily responsible for sales, selection, technical support, and after-sales service of HDSI products in mainland China.
HDSI's early products were mainly mechanical products such as speed reducers. Today, HDSI's main product line includes a wide range of mechatronic products. In the speed reducer field, HDSI primarily offers Harmonic Drive and Harmonic Planetary gear reducers. Its Harmonic Drive harmonic speed reducers have essentially dominated the major international market, possessing characteristics not found in other speed reducers: high rotational/positioning accuracy, compact/lightweight design, high transmission efficiency, high reduction ratio, wide reduction range, high precision, high torque capacity, backlash-free operation, high efficiency, and quiet operation. These features have led to their widespread application in various transmission systems. To cover the low reduction ratio range not covered by harmonic speed reducers, HDSI has also developed the precision planetary gear reducer, Harmonic Planetary. Its unique internal gear ring deformation process allows for tighter meshing of the planetary gears, eliminating backlash and thus controlling transmission errors within a precise range.
A harmonic reducer consists of only three basic components: a flexible wheel, a wave generator, and a rigid wheel. The outer diameter of the flexible wheel is slightly smaller than the inner diameter of the rigid wheel, and typically the flexible wheel has two fewer teeth than the rigid wheel. The elliptical shape of the wave generator determines that the tooth contact points of the flexible wheel and the rigid wheel are distributed on two opposite planes located between the center of the ellipse. During the rotation of the wave generator, the tooth contact points of the flexible wheel and the rigid wheel begin to mesh. For every 180° clockwise rotation of the wave generator, the flexible wheel rotates by the equivalent of one tooth difference counterclockwise on the rigid wheel. At two symmetrical points within 180°, more than 30% of the total number of teeth are engaged simultaneously, which results in its high torque transmission.
HarmonicDrive offers a range of harmonic reducers, including the high-torque CSG series, standard CSF series, ultra-flat and high-load-capacity CSD series, high-torque hollow shaft and input shaft SHG series, hollow shaft and input shaft SHF series, ultra-flat and hollow SHD series, small dual-shaft CSFsupermini series, and standard CSG-GH/CSF-GH series.
Having discussed the birth and development of harmonic reducers, let's now analyze the special bearings for harmonic reducers:
Precision bearings are crucial and fundamental components in the equipment manufacturing industry, directly impacting the performance, quality, and reliability of major equipment and main products; they are often referred to as the "heart" of equipment manufacturing. In industrial robot harmonic reducers, the precision, friction torque, and rigidity of the bearings used directly affect the stability and safe operation of the entire reducer and even the robot. Robot bearings represent a niche market within bearing applications, emerging alongside the rise of the industrial robot industry. Precision bearings for robots mainly include: cross-bearings specifically for harmonic reducers, flexible bearings, RV reducer bearings, crossed roller bearings, and thin-walled bearings with uniform cross-sections.
Harmonic reducer bearings
Harmonic reducer bearings are precision cross-roller bearings specifically designed for harmonic reducers. They mainly consist of two types: the CSF/CSG series (split outer ring, integral inner ring) and the SHF/SHG series (both outer and inner rings are integral). The rolling elements are cylindrical rollers arranged perpendicularly at 90° in a V-shaped raceway. This structure allows a single bearing to simultaneously withstand axial loads, radial loads, and overturning moments. Harmonic reducer bearings possess high rigidity, rotational accuracy, and combined load-bearing capacity; their compact design and built-in mounting holes facilitate direct installation, making them suitable for various types of harmonic reducers.
In recent years, Luoyang Senao Precision Bearing Co., Ltd. has been developing specialized bearings for harmonic reducers. It is a leading domestic manufacturer of cross-shaped bearings for robot harmonic reducers, achieving precision levels of P4 and P2. Founded in 2008, Luoyang Senao Precision Bearing Co., Ltd. has focused on the market for bearings for robot harmonic reducers since its inception. For nearly a decade, the company has dedicated itself to the research and development of bearings for harmonic reducers, serving domestic and international robot manufacturers. In recent years, it has developed a full range of harmonic reducer bearings for industrial robots for hundreds of clients. Through long-term accumulation of experience and mature technology, its technical indicators and precision meet the requirements of similar foreign products. The company receives increasing orders annually, enjoys a favorable market situation, and achieves steady growth in sales performance year after year. Statistics show that these bearings account for approximately 35% of the Chinese industrial robot bearing market, and this share is growing rapidly. In recent years, the company has produced and sold more than 20,000 sets of bearings for harmonic reducers, which have been exported to Europe, America, South Korea, Taiwan, Singapore and other countries and regions at home and abroad. At the same time, it has provided supporting and technical support services to many domestic enterprises and research institutions engaged in the research and development and production of industrial robots and parts.
Although my country's bearing manufacturing technology has made continuous progress in recent years, compared with the world's leading bearing manufacturing countries, there is still a certain gap in various series of precision bearings, such as cross-roller bearings for industrial robot harmonic reducers, RV reducer bearings, and thin-walled bearings with equal cross-sections. This is mainly reflected in the low proportion of high-tech, high-precision, and high-value-added products, and the need for further improvement in product stability. With increased government policy support, it is believed that my country's bearing industry will usher in a period of rapid development, accelerating the localization of precision bearings and providing a solid foundation for the complete localization of China's major equipment manufacturing.
China is actively promoting the development of the industrial robot industry, which is further increasing the demand for high-tech, high-precision precision bearings for robots. This requires domestic bearing manufacturers to continuously improve their technology, accelerate the transformation and upgrading of the bearing industry, narrow the quality gap with imported precision bearings, and achieve the localization of precision bearings.
The way forward for domestic robots lies in quickly overcoming the bottleneck of core components that restrict the development of domestically produced robots. Among these efforts, manufacturers of robot harmonic reducers and supporting bearings should join hands, uniting with leading companies in the industry to form a robot supply chain. Accelerating the localization of robots and related equipment and components is particularly crucial. In recent years, Luoyang Senao Precision Bearing has conducted long-term research and technological breakthroughs in the design, manufacturing, inspection, and application of robot harmonic reducer bearings. In its industrial robot bearing research and production practice, the company has compiled a complete series of supporting bearing products for industrial robot harmonic reducers to standardize and serialize industrial robot bearing production; and formulated enterprise standards for this series of products to better promote the localization of core components for industrial robots. Luoyang Senao Precision Bearing Co., Ltd. specializes in the research and development of industrial robot harmonic reducer bearings, and has made unremitting efforts to achieve high performance, long life, and low cost for robot harmonic reducer bearings as soon as possible, providing robot harmonic reducer manufacturers with high-precision bearings that are "affordable, reliable, and durable," thereby further filling the gap in domestic demand.
Compared to imported harmonic reducer bearings, domestically produced harmonic reducer bearings still have significant advantages. With the improvement of my country's harmonic reducer bearing manufacturing technology, the quality of domestically produced bearings is more guaranteed, and they also have a price advantage, making them highly competitive in the domestic market. The localization of harmonic reducer bearings will change the market situation of these high-precision bearing products, which have long been monopolized by foreign companies and are urgently needed by the domestic market. With the establishment of a number of domestic brand enterprises, the competitiveness of Chinese harmonic reducer bearings in the international market is also increasing, and the domestic and international markets are expanding.
