Home page

Bearing Components and Their Applications

Bearings are an essential component in modern mechanical equipment. Their primary functions are to support rotating machine parts, reduce friction during operation, and ensure rotational accuracy.

Bearings are an essential component in modern mechanical equipment. Their primary functions are to support rotating machine parts, reduce friction during motion, and ensure rotational accuracy. In other words, bearings serve to bear the shaft, guide it, or secure it in place.

At present, China’s bearing industry faces three major challenges: low production concentration, weak R&D and innovation capabilities, and a low level of manufacturing technology.

First, the industry suffers from low production concentration. Of the global bearing market’s roughly US$30 billion in sales, the world’s eight largest multinational corporations account for 75% to 80%. In contrast, China’s ten largest bearing firms—including Wazhou—generate only 24.7% of the entire sector’s revenue, and even among the top 30 companies, production concentration stands at just 37.4%. Second, R&D and innovation capabilities are weak. The industry as a whole conducts limited fundamental theoretical research, plays a minor role in shaping international standards, and produces few original technologies or patented products. Currently, our design and manufacturing techniques are largely imitative, with weak product‑development capacity. This is evident in the fact that, although domestic component‑supply rates reach 80% for many applications, critical components such as high-speed railway passenger car bearings, mid- to high‑end automobile bearings, and bearings used in computers, air conditioners, and high‑performance rolling mills still rely almost entirely on imports for both supply and maintenance. Third, manufacturing technology remains underdeveloped. China’s bearing industry has made slow progress in refining manufacturing processes and process‑equipment technologies; the CNC penetration rate in turning operations is low, and automation levels in grinding are also limited, with fewer than 200 automated production lines nationwide. Moreover, advanced heat‑treatment processes and equipment crucial to bearing life and reliability—such as controlled-atmosphere protective heating, dual refinement, and bainitic quenching—remain poorly adopted, and many key technical challenges have yet to be overcome.

Classification of Bearings

Rolling bearing

Sliding bearing

Linear bearing

Linear bearing with a straight cylindrical design

Flanged linear bearing

Box-type linear bearing

Linear bearing with clamping handle

The difference between rolling bearings and sliding bearings

① Rolling bearings have rolling elements (balls, cylindrical rollers, tapered rollers, and needle rollers), whereas sliding bearings do not have rolling elements.

② Structurally, rolling bearings support the rotating shaft by the rolling motion of rolling elements, resulting in a point contact; the more rolling elements there are, the greater the number of contact points. In contrast, sliding bearings support the rotating shaft via a smooth surface, so the contact is distributed over an entire surface.

③ Secondly, the modes of motion differ: rolling bearings operate by rolling, whereas sliding bearings operate by sliding.

Consequently, the frictional situation is entirely different.

Classification of Rolling Bearing Designations

Prefix code

Basic code

Suffix codes (each bearing manufacturer may use different designations, but they are generally standardized; take NSK as an example)

Bore diameter code

Selection of Rolling Bearings

1. Considerations (load magnitude and direction, rotational speed, misalignment, noise, service life, ease of disassembly, temperature, and cost) (For details, see: Mechanical Design Handbook—Common Bearing Structures.)

2. Experience: Ball bearings are typically used in light-load, high-speed applications, while roller bearings are generally employed in low-speed, heavy-load conditions (with the exception of single-direction bearings).

Cleaning and Lubrication of Rolling Bearings

Reason:

Most newly purchased bearings are coated with grease. Grease is primarily used to prevent rust and does not provide lubrication; therefore, the bearings must be thoroughly cleaned before installation and use.

Methods of cleaning

Clean with gasoline or kerosene: hold the inner ring of the bearing with one hand, and slowly rotate the outer ring with the other until all oil and grime have been thoroughly removed from the rolling elements, raceways, cage, and outer ring.

Installation and Fixing Methods for Rolling Bearings

Installation method:

Cold mounting/mechanical method, also known as the hammering method—suitable for bearing installation with an inner diameter less than 100 mm (preferably using a fixture).

Hot fitting/hydraulic method — for bearing installation with an inner diameter greater than 100 mm

Sliding bearing

Sliding bearings have no inner or outer rings and contain no rolling elements; they are typically made of wear-resistant materials. They are commonly used in low-speed, lightly loaded rotating parts where lubrication is difficult to apply and maintenance is challenging.

Spherical plain bearing

The sliding contact surface of a spherical plain bearing is spherical, making it particularly suitable for oscillating, tilting, and rotary motions.

Rolling bearing

Deep groove ball bearings are the most representative type of rolling bearing. Compared with other bearing types of the same size, they feature a low coefficient of friction, high limiting speeds, a simple structure, low manufacturing costs, and high precision, while requiring minimal routine maintenance. With a wide range of sizes and numerous design variants, they are the most widely used bearing category. They primarily support radial loads but can also accommodate certain axial loads. When subjected solely to radial loads, the contact angle is zero.

Angular contact ball bearing

Spherical roller bearing

Thrust ball bearing

Double-Row Thrust Angular Contact Ball Bearing

Thrust roller bearing

Needle roller bearing

Spherical roller bearing

Flange bearing

Bearing with housing

Combined bearing

Linear bearing

Bearing rusting

Return