Ball Bearings and Miniature Bearings: Dynaroll

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Ball Bearings - Geometry (continued)____________________________________________________________________

CONTACT ANGLE

Contact angle is the angle between a plane perpendicular to the bearing axis and a line joining the two contact points between the ball and the inner and outer raceways. The initial contact angle a_o is defined as the contact angle when the bearing is subjected to a minimal axial load to remove the looseness resulting from radial play. The higher the radial play the higher a_o. Further axial load will increase the contact angle see section on preload.

FORMULAE FOR INTIAL CONTACT ANGLE a_o:

INITIAL CONTACT ANGLE CHART a_o DEGREES (f_i = f_o = 0.56)

BALL DIAMETER (D_w)	DYNAROLL RADIAL PLAY CODE [ dimensions in inches (mm) ]
BALL DIAMETER (D_w)	MC2 (.0001 - .0003) (.003 - .008)	MC3 (.0002 - .0004) (.005 - .010)	MC4 (.0003 - .0005) (.008 - .013)	MC5 (.0005 - .0008) (.013 - .020)
.0236 & 0.6mm	15.1^o	18.6^o	21.5^o	27.5^o
.0315 & 0.8mm	13.3^o	16.3^o	18.9^o	24.1^o
.0394 & 1.0mm	11.9^o	14.5^o	16.8	21.5^o
.0472 & 1.2mm	10.8^o	13.2^o	15.3^o	19.5^o
.0625 (1/16th)	9.3^o	11.4^o	13.2^o	16.9^o
.0787 & 2.0mm	8.3^o	10.2^o	11.8^o	15.0^o
.0937 (3/32nd)	7.6^o	9.4^o	10.8^o	13.8^o
.1250 (1/8th)	6.6^o	8.1^o	9.4^o	11.9^o
.1406 (9/64th)	6.2^o	7.6^o	8.8^o	11.2^o
.1562 (5/32nd)	5.9^o	7.3^o	8.4^o	10.7^o

Note: The above contact angles are given for the mean radial play of the range, i.e. for MC3 (.0002 to .0004 inch),
a_o initial contact angle is for .0003 inch radial play. Use formula to calculate other exact values.

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