GQZ bearing application knowledge: Miniature Bearings - Small Body, Big Purpose

Miniature bearings refer to the metric series with an outer diameter of less than 9mm; the inch series with an outer diameter of less than 9.525mm. The main materials are bearing steel, stainless steel, plastic, ceramics, etc. The minimum inner diameter can be 0.6mm, and the inner diameter is generally 1mm.

Miniature ball bearings are made of carbon steel, bearing steel, stainless steel, plastic, ceramics and other materials. They have a wide range of uses and are suitable for products requiring high-speed rotation, low friction torque, low vibration, and low noise (carbon steel materials are very few customers. used, for low-end clients).


The best miniature bearings in other countries

GQZ miniature bearing

1. The world's smallest steel ball bearing

In Tokyo, Japan, Minebea Co., Ltd. announced that its steel ball has been awarded the Guinness World Records title for the smallest commercial steel ball bearing, certified by a representative from Guinness World Records Co., Ltd. to have an outer diameter of only 1.4978 mm.

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

GQZ mini bearing 

2.The world's smallest fidget spinner can fit on your nails

The smallest fidget spinner in the world. MinebeaMitsumi used what Guinness calls "the smallest commercial steel ball bearings" to make this gadget.

It took a team of eight people two months to build a fidget spinner less than a quarter of an inch (5.09 mm) long. It has the same function as other fidget spinners, but you may need a pair of tweezers to pick it up.

 GQZ bearing smallest fidget spinner

2.1 Product Features

Miniature bearings are suitable for all kinds of industrial equipment, small rotary motors, etc. In recent years, the demand for miniaturization, light weight, and thin-wall type of these devices has increased.

Among the ultra-small bore miniature bearings, there are 18 types of metric 68, 69, and 60 series of miniature bearings with inner diameter below φ2mm, and 6 types of inch R series. On this basis, they can also be divided into ZZ steel plate bearing dust cover series , RS rubber bearing seal series, Teflon bearing seal series, flange series, stainless steel series, ceramic ball series.

GQZ micro bearing

2.2 Main uses and common models

The main purpose:

Office equipment, micro motors, soft drives, pressure rotors, dental drills, hard disk motors, stepping motors, video recorder drums, toy models, computer fans, encoders, etc.

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

 GQZ miniature bearing

2.3 11 elements for selecting miniature bearings

There are many factors that need to be considered when choosing a miniature bearing to avoid selection type and other errors. Here are 11 major elements for choosing a miniature bearing for your reference.

1. Miniature bearing radial load

Bearings that mainly bear radial loads are radial bearings. The nominal contact angle a0 of this type of bearing is less than or equal to 45°, and a roller bearing of the same size can bear a larger radial load than a ball bearing.

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

2. Axial load of miniature bearings

The bearing that mainly bears the axial load is generally a thrust bearing, and its 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 depending on the structure. When the axial force is particularly high, thrust cylindrical roller bearings and thrust spherical roller bearings are preferred.

Thrust spherical roller bearings and one-way thrust angular contact ball bearings can bear both axial and radial loads, while other thrust bearings can only bear axial loads.

3. The length compensation of the miniature imported bearing itself

A shaft and a bearing are usually supported by a combination of a fixed bearing and a floating bearing. The floating bearing compensates for shaft length errors and thermal expansion.

Type NU and N cylindrical roller bearings are ideal for free-standing bearings, which themselves compensate for length. The inner and outer rings of the bearing can be tightly fitted.

 GQZ good quality

2.4  Length compensation for sliding fit of miniature bearings

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

2.5 Separable miniature bearings (precision)


This is a bearing in which the rings can be mounted separately, which is particularly advantageous when both rings have a tight fit.


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 spherical roller bearings.


(I will also introduce a non-separable bearing type here.) Non-separable bearings include: deep groove ball bearings, single row angular contact ball bearings, self-aligning ball bearings, and spherical roller bearings.


2.6  Miniature bearing accuracy


Rolling bearings of normal size and rotational accuracy are sufficient in most cases.


GQZ miniature bearing


2.7 Compensation for non-neutrality of miniature bearings


Misalignment occurs when machining journal mating surfaces or bearing housing mating surfaces, especially when machining of mating surfaces is not done in one clamping. Misalignment can also occur when housings are used (eg flanged housings or plummer housings). Misalignment also occurs when the inner and outer rings of the bearing are tilted due to the bending deformation of the shaft due to the working load.


Spherical bearings can compensate for misalignment and inclination, such as self-aligning ball bearings, radial and thrust spherical roller bearings. These bearings have a concave spherical outer raceway in which the rolling elements and inner ring can rotate. The ability of these bearings to compensate for shaft center deflection depends on their type, size and load conditions.


Insert spherical bearings and thrust ball bearings with races have a spherical bearing surface: when mounted in a concave spherical race, the compensation deflection angle can be adjusted.


2.8 Miniature bearing speed


The friction of single row bearings is particularly low and therefore the highest speeds can be reached. Such bearings include deep groove ball bearings that can only withstand radial loads and angular contact ball bearings that can withstand combined loads.


Improve the dimensional accuracy, rotation accuracy and accuracy of the matching parts of the bearing, the lubrication and cooling method adopted, and the use of a special form of cage can increase the allowable speed of the bearing.


low noise operation

Low operating noise is generally required in small motors, office equipment and household appliances.

When the requirements are higher, the bearings require higher precision classes.

 GQZ good quality miniature bearing

2.9 Miniature bearing tapered bore

Bearings with tapered bores can be mounted directly on tapered journals (eg single and double row cylindrical roller bearings in high precision construction). A given radial clearance can be adjusted when installing this type of bearing.

Most spherical ball bearings, drum roller bearings and spherical roller bearings with a tapered bore can be mounted on a cylindrical journal with an adapter sleeve. These bearings are particularly easy to install and remove.

2.10 Miniature bearing stiffness

The stiffness of well-known bearings usually refers to the force required to produce a certain elastic deformation of the bearing. Bearings on machine tool spindles and pinion shafts require high rigidity. Due to the different contact conditions of rolling elements and raceways, the stiffness of roller bearings is higher than that of ball bearings.

2.11 Miniature bearing friction

In addition to being heated and dissipated, internal friction also plays a significant role in determining the operating temperature of the bearing. Low friction bearings include: deep groove ball bearings with radial loads, miniature single row angular contact ball bearings and cylindrical roller bearings with cages. Bearings with contact seals, full complement cylindrical roller bearings and thrust roller bearings all generate high frictional forces.

GQZ miniature bearing


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