About Steel Ball Bearings

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Inner Ring, Outer Ring, and Ball Bearing Materials

Ball bearings are machined components that include outer ring, inner ring, ball bearings, shielded bearings, snap rings, and more.  Bearing  material,  purity, and hardness are important factors when long life, high efficiency, low torque and low noise level are required by your application.  Careful selection of material is also a factor when applications require bearings to provide superior hardness and anti-corrosion or heat-resistance. NMB has a wide variety of ball bearings, so you can be sure you’ll find the exact ball bearing you need with us. Search for ball bearings by metric and inch sizes, flanged or unflanged bearing options, and by open or shielded bearings. Ring and Ball materials are subjected to severe stress reversals of approximately 1000 MPa. For applications with so many high pressure compressive stress reversals endured for such prolonged periods, an extremely pure and hard material is required. Therefore, careful selection of the raw material is necessary for bearings. NMB uses high performance carbon chromium steel; or when good corrosion resistance is required, martensitic stainless steel. Our high carbon chromium steel is supplied to the specification JIS G4805/SUJ2, AISI/SAE52100 or equivalent, which is hardened, providing long life and high load capacity for our bearings. “DD400″ martensitic stainless steel is a proprietary product of NMB which provides good hardness, long life and good load capacity for steel ball bearings when compared with other equivalents such as SUS440C. NMB Stainless Steel has better carbide distribution than other equivalents and therefore gives improved noise characteristics similar to high carbon chromium steel. NMB Stainless Steel provides the same corrosion resistance results when tested with SUS440C in accordance with test procedure ASTM-A380.

Ball Bearing Material Composition

High Carbon Chromium Bearings

Spec Symbol Chemical Component (wt%)
C Si Mn P S Cr Mo
JIS G 4805 SUJ 2 0.95~1.10 0.15~0.35 0.50 MAX 0.025 MAX 0.025 MAX 1.30~1.60 -
AISI/SAE E52100 0.98~1.10 0.15~0.35 0.25~0.45 0.025 MAX 0.025 MAX 1.30~1.60 -

Stainless steel

Spec Symbol Chemical Component (wt%)
C Si Mn P S Cr Mo
- DD400 0.60~0.75 1.00 MAX 1.00 MAX 0.03 MAX 0.02 MAX 11.50~13.50 0.30 MAX
JISG4303 SUS440C 0.95~1.2 1.00MAX 1.00MAX 0.04MAX 0.03MAX 16.00~18.00 *

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Inner Ring, Outer Ring, and Ball Bearing Materials

Ring and Ball materials are subjected to severe stress reversals of approximately 1000 MPa. For applications with so many high pressure compressive stress reversals endured for such prolonged periods, an extremely pure and hard material is required.  Therefore, careful selection of the raw material is necessary. NMB mainly uses high performance carbon chromium steel; or when good corrosion resistance is required, martensitic stainless steel. Our high carbon chromium steel is supplied to the specification JIS G4805/SUJ2, AISI/SAE52100 or equivalent, which is hardened, providing long life and high load capacity. “DD400″ martensitic stainless steel is a proprietary product of NMB which provides good hardness, long life and good load capacity when compared with other equivalents such as SUS440C.  NMB Stainless Steel has better carbide distribution than other equivalents and therefore gives improved noise characteristics similar to high carbon chromium steel. NMB Stainless Steel provides the same corrosion resistance results when tested with SUS440C in accordance with test procedure ASTM-A380.

Material Composition
High Carbon Chromium Bearing
Standard Grade Chemical Composition wt%
C Si Mn P S Cr Mo
JISG4805 SUJ2 0.95-

1.10 0.15- 0.35 0.5 MAX 0.025 MAX 0.025 MAX 1.3- 1.6 - AISI521000.98- 1.10 0.15- 0.35 0.25- 0.45 0.025 MAX 0.025 MAX 1.3- 1.6 - Stainless Steel

Standard Grade Chemical Compostion wt%
C Si Mn P S Cr Mo
- DD400 0.6-

  0.75 1.00 MAX 1.00 MAX 0.03 MAX 0.02 MAX 11.50- 13.50 0.3 MAX JISG4303SUS440C0.95- 1.2 1.00 MAX 1.00 MAX 0.04 MAX 0.03 MAX 16.00- 18.00 * * It is also possible to add a maximum of 0.75% molybdenum      Back to top –>