The Difference Between Imported Bearings and Domestic Bearings

Bearings are one of the critical components in machinery, and their primary function is to convert rotary motion into linear motion. Bearing precision grades are typically divided into five levels:
Standard, Premium, High-Precision (Special), and Ultra-High-Precision (UHC) grades. Among these, the Standard grade is available in 3 precision levels: P3, P4, and P6. The Premium grade, meanwhile, comes in 2 precision levels: E2 and E3. In practical applications, bearings with precision ratings higher than Grade 5 are used relatively infrequently. Below, we’ll briefly outline some key differences between imported and domestically produced bearings.

I. Visual Differences

1. In terms of size, imported bearings have slightly larger outer diameters, while domestically produced bearings feature slightly larger inner diameters.

2. From the outer surface, imports often feature a coating or embossed raceways, while domestically produced ones typically lack these processes.

3. In terms of color, domestically produced ones have a yellowish hue, while imported ones lean more toward white.

II. Differences in Quality

1. Materials: Domestically, iron-chromium alloy steel is typically used, offering high hardness but relatively poor toughness; internationally, high-speed steel is preferred, providing lower hardness but significantly better toughness.

2. Heat Treatment: Domestically, normalizing followed by tempering—known as quenching and tempering—is commonly used for quality improvement. In contrast, heat treatment processes abroad typically involve either quenching and tempering or carburizing and quenching.

3. Differences in Performance Usage

1. Rolling elements differ in material: domestically produced ones typically use high-quality carbon structural steel or alloy structural steel, which is hot-rolled into shape and then turned; in contrast, imported ones are mostly powder metallurgy products.

2. The cage materials differ: domestically, stamped steel cages are typically used, whereas imported, genuine products from overseas exclusively feature copper-based alloys.

3. Different materials are used for the sealing rings: domestically produced ones mostly feature PTFE as the sealing material, while most of the originally imported, high-quality products from abroad use nitrile rubber instead.

4. Differences in Installation Methods

1. Internal bore diameters vary significantly because domestic production equipment is outdated, preventing the establishment of a uniform standard. As a result, even cylindrical roller bearings of the same model may have inconsistent internal bore diameters.

2. Axial clearance varies—due to technical limitations, domestically produced cylindrical roller bearings cannot consistently guarantee uniform axial clearance.

3. Different types of grease are used—domestically produced tapered roller and spherical roller bearings typically rely mainly on calcium-based and barium-based greases.

4. Different types of rust-preventive oils are available.

5. There are also significant differences in the assembly method.

6. The packaging is also different.

5. Price Differences: Under the same conditions, domestically produced products are significantly cheaper than imported ones.

6. Comparison of Lifespan: Two product types with the same specifications—Standard and High-Precision—differ significantly in lifespan. The standard model lasts more than 10 times longer than the low-precision version, while the high-precision model also outlasts the standard version by roughly 10 times.

7. Comparison in Other Areas It’s easy to tell at a glance whether the two are identical in appearance—but truly understanding their differences requires a deeper level of insight.

Dalian Shifler Bearing Manufacturing Co., Ltd. primarily produces high-precision bearings that serve as a reliable alternative to imported counterparts, designed strictly according to advanced international manufacturing standards—keeping pace with global bearing technology.