Introduction To 440C Stainless Steel Thin-Section Bearings

In our daily lives, we use stainless steel items. Even people who don't know much about bearings are familiar with stainless steel. The most common examples are stainless steel basins, stainless steel water cups, and so on. There are many materials used in a bearing, such as bearing steel, 440C stainless steel, ceramics, nylon, etc. Different materials are used for different working conditions. Stainless steel is suitable for environments with no impact, medium load, and requirements for rust prevention and wear resistance. Similarly, bearings can be classified in many ways, such as servo motor bearings, thin-section bearings, and cryogenic bearings. We will introduce 440C stainless steel thin-section bearings separately, and introduce the 440C stainless steel material and the thin-section bearing type separately.

440C stainless steel, also known as high-carbon martensitic stainless steel, mainly contains three elements: high carbon, high chromium, and molybdenum. The 440C stainless steel used in high-precision bearings is formed through three processes: primary refining in an electric arc furnace, refining in a vacuum induction furnace, and ultra-deep cryogenic stabilization heat treatment. These materials typically possess high hardness, wear resistance, rust resistance, and corrosion resistance. For example, large and well-known international bearing companies such as Kaydon and Silverthin use this material in combination with bearing turning and grinding processes to produce high-quality bearings with 440C stainless steel thin-sections.

After heat treatment at 440C, the hardness can reach HRC58~62, and the wear resistance is close to that of GCr15 bearing steel, but the rated load is slightly lower than that of GCr15 under the same size. 440C stainless steel bearings with uniform cross-section can withstand radial and axial combined loads and can resist corrosion from water vapor, fresh water, weak acids and alkalis, oil, and steam. They can remain rust-free in humid environments, and their magnetic properties and ultra-deep cryogenic stabilization heat treatment can significantly control heat treatment deformation. These characteristics make them suitable for precision rotation applications. 440C stainless steel has better corrosion resistance than ordinary bearing steel and 420 stainless steel, but is weaker than 316L austenitic stainless steel. Therefore, it is not suitable for strong acid, deep sea high salt spray and strong corrosion conditions. Furthermore, its thinner wall thickness makes it less impact-resistant than thick-walled standard bearings, unable to withstand severe impact loads, and its price is also higher than that of ordinary carbon steel thin-walled bearings.

A thin-section bearing  is a type of bearing with a permanently fixed radial cross-section. The larger the inner diameter, the larger the overall outer diameter, but the wall thickness and width remain constant. Compared to ordinary standard bearings, it achieves extreme thinness and lightness, making it specifically designed for confined installation spaces. Standard mass-production precision levels cover P5 (ABEC5) and P4 (ABEC7), suitable for automation, medical, and robotics applications; P2 (ABEC9) is an ultra-high precision custom grade, primarily used in semiconductors, optics, and aerospace radar.

Next, we will introduce the bearing structure. There are three types of bearing structures, all made of 440C stainless steel and can be customized. First is the C-type, a radial contact type with a single-row deep groove ball structure. It is mainly used for radial loads with slight axial forces. Its main application scenarios are low-speed, purely radial rotation, and lightweight equipment. Then there is Type A, which is the angular contact type, with a 30°contact angle. It can withstand radial and unidirectional loads as well as overturning moments, and is often used for shafts that require pre-tightening and precise positioning. Finally, there is the X-type, which is a four-point contact ball type. It has a double track and four-point contact, and can withstand radial, bidirectional axial forces and overturning moments. It is often used in robot joints, turntables, rotary mechanisms, etc.

440C stainless steel thin-section bearing are generally available in open, double-sided iron-sealed, or rubber-lip sealed configurations. The cage can be a 304 or 316L stainless steel crown cage or a PEEK-based PTFE-filled engineering plastic cage.

In summary, 440C stainless steel bearings have the following advantages:

1. Space-saving and lightweight: With a large inner diameter and extremely thin wall thickness, the weight is reduced by 50%+ and the radial space is saved by about 40%. The hollow shaft structure facilitates wiring and is the core solution for compact equipment.

2. it combines rust prevention and wear resistance. GCr15 bearing steel is extremely prone to rust and failure in humid environments, while ordinary 304 stainless steel bearings have a hardness of only about HRC25 and are easily worn under heavy loads. 440C perfectly balances the two, increasing the service life several times over in humid conditions.

3.it has high rotational accuracy and rigidity. The ultra-thin wall structure has been stress-optimized, resulting in strong anti-overturning moment, low runout, and slow accuracy decay over long-term operation.

Currently, the most mainstream applications of 440C stainless steel bearings thin-section bearing are the joints of robotic arms, end effectors, and waist slewing bearings in industrial robots. They can also be used in surgical instruments of medical equipment, CT turntables, dental equipment, and shafts in sterilization environments, as well as in testing turntables, lens focusing mechanisms, and rotating parts of vacuum equipment in semiconductor or optical instruments.

Liaocheng Zhuoyi Bearing Co., Ltd. was established in 2019. Its trade and technology teams are located in Liaocheng, while its production plant is located in Guantao Bearing Industrial Park in Handan, Hebei Province, adjacent to Yandian Bearing Industrial Belt in Shandong Province. Relying on the supply chain of the Luxi Bearing Cluster, it has the qualifications to produce and process high-quality bearings.

Our company's main brand is TKW, and our product types include 440C stainless steel thin-walled bearings with equal cross-sections, precision stainless steel bearings, hybrid ceramic bearings, and precision bearings for special working conditions. We can produce various stainless steel bearings: 304/316L/420/440C deep groove ball and angular contact miniature precision bearings; hybrid ceramic bearings: motor insulation and anti-electrolytic corrosion bearings, high-speed spindle bearings; special working condition bearings: ultra-low temperature LNG pump bearings, vacuum pump bearings, new energy motor bearings; light-duty slewing bearings, miniature turntable bearings and related products.

It can be used as a domestic substitute for imported Kaydon/Silverthin bearings, for B2B exports to Europe and the United States, and to support your overseas bearing promotion business. We outsource production while maintaining our own production lines; we excel at precision small-batch customization, sample making, and delivery of foreign trade orders, offering convenient communication and rapid after-sales response across different regions.