DIN 988:2025-12

Shim rings are used to precisely position machine parts in axial direction. They are preferably used to compensate for play when axially securing machine parts using retaining rings in accordance with DIN 471, DIN 472, DIN 983, and DIN 984, as well as retaining washers in accordance with DIN 6799. Supporting rings are used in conjunction with retaining rings or retaining washers when there is a risk that large axial forces may cause the retaining rings or retaining washers to be turned inside out due to chamfers or bevels on the machine parts. Supporting rings can also be used together with shims. This document specifies the dimensional requirements and technical specifications for shims and supporting rings and provides their designations. The responsible standardization committee is Working Committee NA 067-00-11 AA "Scheiben und Ringe" ("Washers and rings") at FMV.