d - 4 mm

D - 9 mm

B - 4 mm

C - 4 mm

d1 - 5,2 mm

d2 - – mm

r1 min. - 4,8 mm

r2 min. - 4,8 mm

D1 - 8,1 mm

D2 - 0,1 mm

da min. - 5,1 mm

Da max. - 8,2 mm

ra max. - 0,1 mm

Weight - 0,0009 Kg

Basic dynamic load rating (C) - 0,364 kN

Basic static load rating (C0) - 0,114 kN

Fatigue load limit (Pu) - 0,005

Reference speed - 140000 r/min

Limiting speed - 70000 r/min

Calculation factor (f0) - 6,5

Calculation factor (kr) - 0,02

• Model Number: W638/4-2Z
• Inner Diameter：4mm Outer Diameter：9mm Width：4mm
• Type：Deep Groove Ball Bearings
• Update date：2025-12-14
• Application:Laser Devices,wire industry,Vertical machining,hook,Cylinder Micro,packaging machinery,pipe fittings Steel industry,welding equipment,stamping die and its equipment,horizontal processing,Broadcasting System
• Similar models:SKF W63805R-2Z SKF W63804-2RS1 SKF W638/9-2Z SKF W638/2XR-2Z NSK 638ZZ1 ZEN S638-2RS NSK 638 ISB F63802ZZ SKF W63801-2RS1 ISO 63803ZZ
• BEARING POWER International Trading Co.,Ltd. specialize in W638/4-2Z products，there is large inventory of SKF W638/4-2Z . We has been built up long-term cooperation with SKF company, could make a bulk order of the W638/4-2Z Which SKF W638/4-2Z is the most authentic, must choose BEARING POWER, what a whole variety, reasonable price, guaranteed quality, prompt delivery via Global express.Any inquiry, never hesitate to E-mail or call +86-022-58519721 to contact us.

• Model No.	Inner Diameter	Outer Diameter	Width	Brand	Type
  AST650 F314035	31,5	40		AST	Plain Bearings
  4435	66,675	104,77	28,58	INA	Thrust Ball Bearings
  6321ZZ	105	225	49	NACHI	Deep Groove Ball Bearings
  6705ZZ	25	32	4	FBJ	Deep Groove Ball Bearings
  749A/742	82,55	150,089	44,45	CX	Tapered Roller Bearings
  7917DF	85	120	18	NTN	Angular Contact Ball Bearings
  9101PP	12	28	8	Timken	Deep Groove Ball Bearings
  ASTB90 F10090	100	105		AST	Plain Bearings
  GEEW63ES	63	95		AST	Plain Bearings
  GEG50ES	50	90	56	FBJ	Plain Bearings
  M667935/M667911G2	387,248	546,1	87,312	NTN	Tapered Roller Bearings
  N28/900	900	1090	112	ISO	Cylindrical Roller Bearings
  NUP414	70	180	42	CX	Cylindrical Roller Bearings
  NU205	25	52	15	FAG	CYLINDRICAL ROLLER BEARINGS
  222SM170T	170	340	92	FAG	SPLIT SPHERICAL ROLLER BEARINGS
  207-SFFG	35	72	17	MRC	DEEP GROOVE BALL BEARINGS
  61908-2RS1	40	62	12	SKF	DEEP GROOVE BALL BEARINGS
  RLS-271/2-L	9.5000	15.1250	2.0000	CONSOLIDATED	CYLINDRICAL ROLLER BEARINGS
  87440				CONSOLIDATED	THRUST ROLLER BEARINGS
  KM-18			16	CONSOLIDATED	LOCKNUTS