Tolerances

GLYCODUR^® plain and flanged bushings can be located by means of interference fits. For “ready to fit” bushings and flanged bushings in metric sizes, it is recommended to machine the housing for bearings up to 4 mm bore diameter to an H6 tolerance and to an H7 tolerance for larger bearings (GLYCODUR^® F and GLYCODUR^® A).

After the installation, the bore diameter of the bushings and the bearing clearance will be within the limits indicated in the tables (GLYCODUR F and GLYCODUR A), provided the shaft was also manufactured to the tolerances indicated in these tables. The values for bearing clearance apply to room temperature; if the operating temperature is increased, the bearing clearance is reduced by 0.0016 mm (6.3 x 10^-5 in) for each 20 °C (68 °F) temperature increase for GLYCODUR F bearings, and by 0.005 mm (20 x 10^-5 in) for GLYCODUR A bearings.

The bearing clearance can be reduced or increased within the recommended limits by matching shaft and housing bore to each other during installation.

In certain applications or if the bearing load is low or where minimum running resistance is called for, it is recommended to select the maximum values for bearing clearance indicated in the tables.

The recommended tolerances and indicated approximate values apply to housings made of steel or cast iron. For light alloy housings it may require a higher degree of interference fit due to the difference in thermal expansion. Otherwise, the bushings could become loose.

If it is impossible to use an interference fit because of mounting difficulties or because the force needed for pressing in is too high, it is possible to secure the bushing in the housing bore by gluing. In special cases where adhesive is used it may be necessary to modify the shaft tolerance to avoid improper bearing clearance. Thrust washers are generally secured in machined recesses in the housing. Appropriate diameters and tolerances for the recesses are given in the thrust washers tables.

When determining housing and shaft tolerances attention should be paid to ISO 3547 and ISO 6525 standards.