Miniature & Extra Small Ball Bearings
638 Miniature & Extra Small Ball Bearing
8 × 28 × 9 mm
638 is a miniature & extra small ball bearing from the MX-3 series with a 8 mm bore, a 28 mm outside diameter and a 9 mm width. It has a dynamic load rating of 4,095 N and a static load rating of 1,773 N and a speed rating of 25,200 rpm (oil lubrication), weighing about 27 g. The radial cross-section (D − d) is 20 mm.
Brands: NTN, FAG, SKF, NBC, DTC, SLS
638 Specifications
| Bearing No. | 638 |
|---|---|
| d (Bore) | 8 mm |
| D (Outer Dia.) | 28 mm |
| B (Width) | 9 mm |
| Dynamic Load | 4,095 N |
| Static Load | 1,773 N |
| Max. RPM | 25,200 |
| Weight | 27 g |
| Series | Open Type Miniature & Extra Small Ball Bearings (6mm–9mm bore) |
638 Variants & Designations
Typical designations for this size, subject to availability. Full suffix meanings are listed on the MX-3 series page.
638-ZZ
metal shields on both sides
638-2RS
rubber seals on both sides
Neighbouring Sizes in the MX-3 Series
638 — Frequently Asked Questions
What are the dimensions of the 638 bearing?
The 638 has a bore (d) of 8 mm, an outside diameter (D) of 28 mm and a width of 9 mm, so it is written 8 × 28 × 9 mm.
What is the load rating of the 638?
Dynamic load rating 4,095 N and static load rating 1,773 N. The speed rating is 25,200 rpm with oil lubrication; for grease lubrication use about 75% of that value.
Is the 638 available with seals, special clearance or other options?
Yes, subject to availability. Typical designations include 638-ZZ (metal shields on both sides), 638-2RS (rubber seals on both sides). Tell us the exact designation you need in a quote request.
Which other bearings have the same 8 mm bore as the 638?
Other miniature & extra small ball bearings with a 8 mm bore include F8M12 (12 mm OD), 8M12 (12 mm OD), F8M14 (13.2 mm OD), F688 (14 mm OD). A larger outside diameter generally means a higher load rating.
Do you supply the 638 bearing across India?
Yes. Logass Trade Centre supplies the 638 Pan India with technical support, from single pieces to bulk orders. Use the quote button to share your quantity and brand preference.
Need pricing on the 638?
Share your quantity and preferred brand — our technical team will confirm availability and pricing within one business day.