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Dynaroll: Ball Contact Angle for Ball Bearings

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BALL 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 ao 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 ao. 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), ao initial contact angle is for .0003 inch radial play. Use formula to calculate other exact values.

GRAPH OF a_o Vs RADIAL PLAY FOR DIFFERENT BALL SIZES (f_i = f_o = 0.56)