Bearing Tolerances

The special properties of plastic materials need to be considered during the design stage, including the required minimum tolerances.

In the case of iglide bearings, it is imperative to distinguish between initial and operational tolerances. Initial tolerance refers to the tolerance which occurs immediately after the bearing is fitting. Operational tolerance refers to the tolerance which is the effect of bearing operation.

During continuous operation, surface temperatures of 120°F - 175°F are easily reached. This offers great advantages as the abrasion resistance of iglide bearings is best suited for the temperature range. Temperature increases result in reduced running clearance.

Specific running clerarances for each material are given in the materials spec sheet.

Tolerances for length and flange diameter - Inch Sizes, dimensions in inches

Bearing Length Range Bearing Length (b1) Flange Diameter (d3)
.125 < length <= .375 +0 / -0.0087 -0.0016 / -0.0102
.375 < length <= .6875 +0 / -0.0106 -0.0020 / -0.0126
.6875 < length <= 1.125 +0 / -0.0130 -0.0026 / -0.0156
1.125 < length <= 1.9375 +0 / -0.0150 -0.0031 / -0.0185
1.9375 < length <= 3.375 +0 / -0.0180 -0.0040 / -0.0220


Length of Lead-In Chamfer F, 30o - Inch Sizes Bearing ID

.02

ID <= .375

.03

.375 < ID <= 1.18

.05

ID > 1.18

Tolerances for length and flange diameter - Metric Sizes, dimensions in millimeters

Bearing Length Range Bearing Length (b1) Flange Diameter (d3)
1 < length <= 10 +0 / -0.221 -0.0041 / -0.259
10 < length <= 17 +0 / -0.269 -0.0051 / -0.320
17 < length <= 28 +0 / -0.330 -0.066 / -0.396
28 < length <= 49 +0 / -0.381 -0.079 / -0.470
49 < length <= 75 +0 / -0.457 -0.102 / -0.559


Length of Lead-In Chamfer F, 30o - Inch Sizes Bearing ID

.05

ID <= 10

.08

10 < ID <= 30

1.2

ID > 32

Clearances

In each section there is a table that shows the resulting clearances between shaft and bearing after assembly. The clearances are designed to ensure that the bearings will operate in all temperatures and environmental conditions. Tighter clearances are possible either by decreasing the bore size or by modifying the shaft. Fiber re-inforced iglide grades such as G300, L280 and T500 can be assembled at a tighter clearance than iglide M250 and A200 due to their lower thermal expansion. Larger clearances are necessary when an iglide bearing is submerged in water.