Home Blog Miniature Bearings (ZZ Series) Served as a Catalyst for UAV Equipment

Miniature Bearings (ZZ Series) Served as a Catalyst for UAV Equipment

Release time : 2022-08-01 09:12:43

With the rapid development of the science & technology, drones are widely used in various industries, such as military, weather detection and image data transmission. They can accomplish difficult flight tasks, unmanned. With the help of the radio remote control, drones can operate smoothly. Recently, Lily Bearing helped a drone manufacturer customize a solution of miniature bearings, which are used in the drone gimbal.

The gimbal is a kind of component on the drone which serves as a platform for the body to connect to the camera. This client's UAV gimbal is driven by brushless motors which can sense the movement of the camera body with the help of sensors and can keep the camera stable in the horizontal, rolling or pitching direction through the motors to offset the negative impact of the vibration of the camera body.


After having a good knowledge of the client's working conditions, engineers from Lily Bearing suggested using miniature bearings of MR117ZZ, 683ZZ and MR84ZZ for the client’s UAV heads. They also gave some professional interpretation for the relevant parameters of these miniature sealed bearings. They pointed out that several important factors must be taken into account while choosing miniature precision bearings on UAV heads. These factors include not only the bearing materials, the design, the load, the sealing factors, but also the cages, ABEC grade, the radial clearance as well as the lubrication.

As far as the bearing materials are concerned, the ring material and the ball material of these miniature bearings are all made of the 52100 chrome steel. The chrome steel material has characteristics of the high load capacity and low noises. Further, both the material of cages and the material of seals are made of 300 series stainless steel, which is able to withstand high loads and high rotational speeds. Meanwhile, this stainless steel has anti-rust function. Both the chrome steel and the chrome steel can provide a higher strength-to-wear ratio, which plays a key role in the life extension and the efficient operation of miniature bearings.

Miniature Bearings

Miniature Bearing

In terms of the inner and outer diameter and the width, engineers provided specific instructions. Inner and outer diameters of MR117ZZ series miniature bearings are 7mm and 11mm respectively. Inner and outer diameters of 683ZZ series miniature bearings are 3mm and 7mm respectively. MR84ZZ series miniature bearings have inner and outer diameters of 4mm and 8mm respectively. The tolerance of inner and outer diameters of these three series of miniature bearings is -0.008mm to 0. In addition, the width of all these miniature bearings is 3mm and the width tolerance is -0.12mm to 0.

Whats more, a detailed analysis about the bearing structure, the load direction and the max speed were given. The structures of all the three series of miniature bearings have single-row structures. Their load direction is radial, and therefore all of them can withstand very high radial load. However, there are some slight differences in the specific static and dynamic radial load magnitudes. The MR117ZZ miniature bearings have a dynamic radial load of 387N and a static radial load of 162N. 683ZZ series have a dynamic radial load of 264N and a static radial load of 90N. MR84ZZ miniature bearings have a dynamic radial load of 336N and a static radial load of 113N. The MR117ZZ miniature bearings have a max speed (*1000rpm) of 43; the 683ZZ series have a max speed of 63; and the max speed of MR84ZZ series is 56. All these miniature bearings can provide reliable high performance at low operating torques for moderate radial loads as well as thrust loads.

About the clearance, the radial clearance of MR117ZZ, 683ZZ, MR84ZZ miniature bearings are all graded MC3. MC1/2/4/5/6 is also available. Clearances of these mini bearings range from 0.002mm to 0.013mm. Engineers pointed out that the internal clearance is a very important factor in the operation of miniature bearings. It has a great impact on other factors such as the noise, the vibration, the heat and even the fatigue life. influence. Regardless of the design of the bearing components, it is necessary to apply preload to the inner rings of the bearings in order to eliminate play and improve the stiffness of the bearings.

In terms of the seal type, all the three series of miniature bearings are shielded. This type of seal can not only prevent particles from contaminating the bearings, but also ensure that the lubricant can reach the relevant parts smoothly.

The following is the comparison table among MR117ZZ, 683ZZ and MR84ZZ.

Comparison of MR117ZZ, 683ZZ and MR84ZZ

The engineers also made some analysis about the potential risks of the high noises and the high torque in these miniature bearings. He pointed out that if excessive forces are applied in the assembly of these miniature bearings, they may trigger damages to the raceways of the bearings, which in turn may lead to the increase of the torque as well as noise levels and the shortening of the bearing life. In addition, bearing misalignment is a potential source of high noise and high torque levels. Smaller bearings can usually tolerate misalignments of about 1°. The locating shoulders of the mating components must remain parallel to the bearing raceway surfaces. The shaft and the bearing housing must be concentric with each other, especially when two or more miniature bearings share a common component.

The engineers also gave advice on the conservation of the above miniature bearings. First of all, these miniature bearings need regular lubrication or built-in bearing lubrication to maintain the smooth operation as well as the long life. Second, before using these miniature bearings, it is not allowed to expose them to the environment. It is not permitted to hold small bearings with bare hands. Finger gloves or surgical gloves containing talcum powder are needed to wear. Moreover, when wiping components of miniature bearings, to avoid introducing the lint, a special lint-free cloth need to be used. Ordinary cotton swabs and cleaning cloth should never be used. Furthermore, vibration or shock loads can endanger these miniature bearings, especially if the axial play is eliminated by preloading. Dropping of the preloaded assembly, or placing it on a hard surface, can cause the bearing contact surface to be shocked. To prevent the damage to these miniature bearings caused by undesirable shocks, the shock absorbing material should be covered on the assembly work surface.

In fact, miniature bearings from Lily Bearing cover many sorts, and the above three series are only three small categories of metric size miniature ball bearings. The Miniature Bearing Catalogue offers a complete range of miniature bearings, including the size selection, the price inquiries, as well as free CAD drawings for download. In addition, the size and the capacity selection of micro bearings may be relatively limited and therefore it might be a challenge for high load projects. In such cases, engineers from Lily Bearing will provide clients with professional solutions of customized bearings on the basis of clients' working conditions as well as their special needs.