What are the main differences between R series bearings and metric series bearings?

1. Dimension measurement unit
R series bearings: use inches as the dimension measurement unit and belong to the imperial dimension series.
Metric series bearings: use millimeters (mm) as the dimension measurement unit and comply with international metric standards.

2. Size range
R series bearings: The inner diameter range usually starts from 0.1875 inches (about 4.7625 mm) to about 1.5 inches (38.1 mm), suitable for various applications under the imperial dimension standard.
Metric series bearings: The inner diameter range is wide, ranging from a few millimeters for small bearings to hundreds of millimeters for large bearings, meeting applications of different scales and load requirements.

3. Design standards
R series bearings: Design standards usually follow the imperial standard regulations, such as American standards such as ANSI, ASTM or other imperial countries.
Metric series bearings: Design standards follow international metric standards, such as those set by international standard organizations such as ISO and DIN.

4. Applications
R series bearings: Mainly used in the United States and other countries that adopt the imperial measurement system, suitable for industrial, mechanical, automotive and other fields in these countries.
Metric series bearings: Widely used worldwide, suitable for various international standards and general specifications of mechanical equipment and engineering applications.