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Miniature & Instrument Bearings

MINIATURE BEARINGS

Part Numbering System

IMPORTANT NOTE:
The National Precision Bearing numbering system identifies ball bearing size and design. This system is not a guide to create a customized ball bearing. Please use the numbering system to decipher the basic bearing numbers listed in the catalog, or to define a number given to you by a representative of National Precision Bearing. Please consult a member of the National Precision Bearing sales or engineering staff to help you design a new bearing or to interchange another manufacturer's part number.

MINIATURE BEARINGS | PART NUMBERING SYSTEM
Example: SS RI 418 ZZ H A5 P25 LO2
NPB PART NUMBER ADDITIONAL SPECIFICATIONS
GROUP 1 GROUP 2 GROUP 3 GROUP 4 GROUP 5 GROUP 6 GROUP 7 GROUP 8 GROUP 9 GROUP 10 GROUP 11
Material Type Basic Size Seals &
Shields
Modifications Premium
Features
Cage ABEC
Tolerance
Radial
Play
Torque Lubricant
SS RI- 418 ZZ   H A5 P25   LO2
SS= AISI stainless steel (440C)

No Code= Chrome alloy steel (52100)

SE= AISI stainless steel rings (440C) with ceramic balls

DD™= NMB 400 Series martensitic stainless steel

S= 400 Series martensitic stainless steel (Std. Ref.)

DS™= 400 Series high performance stainless steel and 440C balls

RI, R, L= Radial

RIF, RF, LF= Flanged Radial

F= Flanged, Tapered O.D.

MBRI, MBR, MBL= Inner ring relieved and separable

MBRIF, MBRF, MBLF= Inner ring relieved and separable, flanged outer ring

MDRI, MDR, MDL= Inner ring relieved and non-separable

MDRIF, MDRF, MDLF= Inner ring relieved and non-separable, flanged outer ring

MERI, MER, MEL= Outer ring relieved and non-separable

MERIF, MERF, MELF= Outer ring relieved, flanged and non-separable

MBF= Inner ring relieved and separable, outer ring flanged and O.D. tapered

MDF= Inner ring relieved and non-separable, outer ring flanged and O.D. tapered

Inch Series
First one or two digits indicates O.D. in 16ths of an inch. The following two or three digits indicate the bore size in a fraction of an inch, the first digit being the numerator and the second or the second and third digits being the denominator.

Metric Series
First two digits indicate O.D. in mm. Second two digits indicate I.D. in mm.

X= (following basic size) Indicates special internal design, assigned in numerical sequence, i.e. X1, X2, etc.

Enclosures

Z= Single metallic shield-removable

ZZ= Double metallic shield-removable

ZO= Single shield on side opposite flange

D= Single rubber seal

DD= Double rubber seal

2RS= Two rubber seals

D1= Single Viton® seal

DD1= Double Viton® seal

L= Single glass-reinforced PTFE seal

LL= Double glass-reinforced PTFE seal

LO= Single seal on side opposite flange

LZ= Glass reinforced PTFE seal and shield with seal on flange side

ZL= Shield and glass reinforced PTFE seal with shield on flange side

H= Single metallic shield non-removable

HH= Double metallic shield non-removable

K= Single metallic shield non-removable

KK= Double metallic shield non-removable

S= Single rubber seal, non-contact

SS= Double rubber seal, non-contact

Extended Inner Ring

EE= Both sides

E= One side


Special External Dimension

A_ _ = Larger than standard O.D.

A= Semi-standard, larger width and O.D. bearing

A_ _ _ _= Larger O.D. than standard and special width

W= Wider than standard width

Y= Narrower than standard width

N= Larger or smaller bore than standard


Special Design

SD= Special design bearing

MC= Premium ball & race finish for specific applications

MT= Noiseless motor quality

CR= Ribbon PTFE coated

F= Full ball complement

H= Crown, land piloted

J= Crown, acetal

KB= Crown phenolic, paper base

KC= Crown phenolic, linen base

KF= Crown phenolic, linen, non keyhole type, outer land piloting

KG= Crown phenolic, paper base, outer land piloted

KM= Full type, phenolic, linen base

KN= Full type, phenolic, paper base

M4= Full type, polyimide

M5= Crown, polyimide

R= Ribbon, land piloted

RD= Ribbon, ball piloted

SF= Composite metal polymer retainer "silver"

T1= Crown, specialty material

A1= ABEC 1*

A3= ABEC 3, 3P

A5= ABEC 5, 5P, 5T

A7= ABEC 7, 7P, 7T

A9= ABEC 9, 9P

Note: Selected ABEC 9 tolerances are available on all sizes. Please consult NPB.

* A1 miniature and instrument bearings of both the metric and inch configurations meet the tolerances of ABMA Standard 20 for ABEC 1 metric series bearings

P= Followed by two, three, or four numbers indicates the radial play limits in ten thousandths of an inch. Example: P25 indicates radial play of .0002” to .0005”.

T= Followed by a number that indicates maximum starting torque in hundreds of mg. mm. Example: T15 indicates a maximum starting torque of 1500 mg. mm.

RT= Followed by a number that indicates maximum running torque in hundreds of mg. mm. Example: RT15 indicates a maximum running torque of 1500 mg. mm.

Lubricant letter codes are followed by a number to indicate specific type

BC= Following lubricant code indicates barrier coating

LB= Mixture of oil and solvent

LD= Dry, no lubricant

LF= Dry film

LG= Greases

LM= Mixture of oil and grease

LO= Oils

LY= Expanded list of oils and greases


Grease Plate Code (follows lubricant code)

GPL= Light

GPM= Medium

GPH= Heavy


 Note:
 Radial Load Ratings shown are for 52100 chrome steel.
 DD™ is a Trademark of NMB Corporation.
 DS™ is a Trademark of the NHBB Corporation.
 Viton® is a Registered Trademark of Dupont Corporation.