Miniature bearing refers to metric series with outer diameter less than 9mm; British series, all kinds of bearings with outer diameter less than 9.525mm. The main materials are bearing steel, stainless steel, plastic, ceramics, etc. The minimum inner diameter can be 0.6mm, and generally more are 1mm.

The miniature ball bearing is made of carbon steel, bearing steel, stainless steel, plastics, ceramics and other materials. It has a wide range of applications and is suitable for products with requirements of high-speed rotation, low friction torque, low vibration and low noise (carbon steel materials are rarely used by customers, and are used by low-end customers).

The largest number of miniature bearings in other countries

The world's smallest steel ball bearing

In Tokyo, Japan, Meibei Co., Ltd. announced that its steel ball was awarded the Guinness World Records title of the smallest commercial steel ball bearing. The representative of Guinness World Records Co., Ltd. certified that its steel ball's outer diameter was only 1.4978 mm.

The dimensions of this record bearing are 1.5 mm outside diameter, 0.5 mm inside diameter, and six steel balls in a length of 0.65 mm wide. Its compactness and precision conform to JIS code.

The world's smallest fingertip top can be placed on your fingernails

The world's smallest fingertip top. Minebea Mitsumi used what Guinness calls "the smallest commercial steel ball bearing" to make this gadget.

A team of eight people spent two months building a fingertip gyroscope less than a quarter of an inch in length. It has the same function as other fingertip gyroscopes, but you may need a pair of tweezers to pick it up.

1. Product characteristics

Miniature bearings are suitable for various industrial equipment, small rotary motors, etc; In recent years, the demand for miniaturization, lightweight and thin-wall of these devices has increased.

In micro bearings with super small bore, the inner diameter φ There are 18 types of metric 68, 69, 60 series and 6 types of inch R series of micro bearings below 2mm. On this basis, they can also be divided into ZZ steel plate bearing dust cover series, RS rubber bearing seal ring series, Teflon bearing seal ring series, flange plate series, stainless steel series, ceramic ball series, etc.

2. Main applications and common models

Main purpose:

Office equipment micro motor, soft drive pressure rotor, dental drill hard disk motor, stepping motor video recorder drum, toy model computer fan, encoder and other fields.

Common models:

682 682ZZ MR52 MR52ZZ 692 692ZZ 683 683ZZ MR83 MR83ZZ 693 693ZZ 603 603ZZ 623 623ZZ MR74 MR74ZZ MR84 MR84ZZ 684 684ZZ MR104 MR104ZZ 694 694ZZ 604 604ZZ 624 624ZZ MR85 MR85ZZ MR95 MR95ZZ MR105 MR105ZZ 685 685ZZ MR115ZZ 695ZZ 605ZZ 625ZZ

MR106 MR106ZZ MR126 MR126ZZ 686 686ZZ 696ZZ 606ZZ 626ZZ MR117 MR117ZZ MR137 MR137ZZ 687 687ZZ 607ZZ 627ZZ MR128 MR128ZZ MR148 MR148ZZ 688 688ZZ 698ZZ 608ZZ MR149 MR149ZZ 689 689ZZ 609ZZ 629ZZ 639ZZ 6000ZZ 16001ZZ 6200ZZ

3. 11 key elements for selecting miniature bearings

Many factors need to be considered when selecting miniature bearings to avoid selection type and other errors. Now, 11 major factors for selecting miniature bearings are summarized for your reference.

(1) Radial load of micro bearing

The bearing mainly bearing radial load is radial bearing. The nominal contact angle a0 ≤ 45 ° of this type of bearing, and the roller bearing with the same size can bear more radial load than the ball bearing.

N-type and NU type cylindrical roller bearings can only bear radial load, while other types of radial bearings can bear both radial load and axial load.

(2) Axial load of miniature bearing

The bearing mainly bearing axial load is generally thrust bearing, whose nominal contact angle a0>45°. Thrust bearing and thrust angular contact ball bearing can bear axial force in one or two directions at the same time according to different structures. When the bearing force is especially high, the thrust cylindrical roller bearing and thrust self-aligning roller bearing are preferred.

Thrust self-aligning roller bearing and one-way thrust angular contact ball bearing can bear axial load and radial load at the same time, while other thrust bearings can only bear axial load.

3. Length compensation of miniature inlet bearing

Supporting a shaft and bearing is usually a combination of fixed bearing and movable bearing. The movable bearing compensates the length error and thermal expansion of the shaft.

NU type and N type cylindrical roller bearings are ideal floating bearings, which can compensate the length by themselves. The inner and outer rings of the bearing can be fitted tightly.

4. Length compensation of micro bearing sliding fit

Non separable miniature bearings (such as deep groove ball bearings and self-aligning roller bearings) can also be used as floating bearings. One of the two rings of this type of bearing is matched and has no axial fixed surface. Therefore, one ring of the bearing can move on its bearing surface.

5. Detachable miniature bearing (precision)

This is a bearing whose rings can be installed separately, and its advantages are very prominent when both rings are tight fit.

The separable bearings include four point contact ball bearings, double row angular contact ball bearings with double half inner rings, cylindrical roller bearings, tapered roller bearings, thrust ball bearings, thrust cylindrical roller bearings and thrust self-aligning roller bearings.

(A type of non separable bearing is also introduced here.) Non separable bearings include: deep groove ball bearing, single row angular contact ball bearing, self-aligning ball bearing, and self-aligning roller bearing.

6. Precision of miniature bearing

In most cases, it is sufficient to apply rolling bearings of general size and rotation accuracy.

When the requirements are higher, the bearing needs a higher accuracy level.

7. Compensation for non neutrality of miniature bearing

The misalignment occurs when machining the journal fitting surface or bearing seat fitting surface, especially when the machining of the fitting surface is not completed in a single clamping. Misalignment can also occur when using bearing housings, such as flanged or vertical bearing housings. Due to the bending deformation of the shaft caused by the working load, the misalignment will also occur when the inner and outer rings of the bearing tilt.

Self aligning bearings can compensate for misalignment and inclination, such as self-aligning ball bearings, radial and thrust self-aligning roller bearings. This type of bearing has a concave spherical outer race, in which the rolling element and inner race can rotate. The ability of these bearings to compensate the shaft center deflection angle depends on their own type, size and load conditions.

Both the outer spherical bearing and the thrust ball bearing with race have a spherical bearing surface: when installed in the concave spherical race, the compensation deflection angle can be adjusted.

8. Micro bearing speed

The friction of single row bearing is especially low, so the maximum speed can be reached. This kind of bearing has deep groove ball bearing which can only bear radial load and angular contact ball bearing which can bear joint load.

The allowable speed of the bearing can be increased by improving the size accuracy, rotation accuracy and fitting accuracy of the bearing, adopting lubrication and cooling methods and using special cages.

Low noise operation

In small motors, office equipment and household appliances, the running noise is generally required to be low.

9. Conical bore of miniature bearing

Bearings with tapered holes can be mounted directly on tapered journals (for example, single row and double row cylindrical roller bearings in high-precision structures). The given radial clearance can be adjusted when installing such bearings.

Most self-aligning ball bearings, drum roller bearings and self-aligning roller bearings with tapered holes can be fitted to cylindrical journals by means of an adapter sleeve. This type of bearing is particularly easy to install and remove.

10. Micro bearing stiffness

The stiffness of imported bearing usually refers to the force required to make the bearing produce certain elastic deformation. The bearings on the machine tool spindle and pinion shaft are required to have high stiffness. Because of the different contact conditions between rolling element and raceway, the stiffness of roller bearing is higher than that of ball bearing.

11. Micro bearing friction

In addition to being heated and dissipated, internal friction also plays a significant role in determining the working temperature of the bearing. Low friction bearings include: deep groove ball bearing bearing bearing radial load, micro single row angular contact ball bearing and cylindrical roller bearing with cage. Contact sealed bearings, full loaded cylindrical roller bearings and thrust roller bearings will all produce greater friction.

More about FRC Miniature Bearing：

As one of the most professional miniature bearing manufacturers and suppliers in China, we’re featured by good service and competitive price. Please rest assured to buy high quality miniature bearings from our factory. Contact us for dimensions and specifications.

Miniature bearings are sometimes referred to as instrument bearings or micro bearings and are used in applications as varied as gyros, anemometers, flow meters, miniature gearboxes, small motors and radio controlled models.

Miniature bearings are available in bore sizes ranging from 1mm and are utilized in thousands of applications, such as radio controls, watches, fishing reels, instrumentation, and any other small application where minimization of friction of small rotating parts is important.