ISO 21940-32:2012

Mechanical vibration — Rotor balancing — Part 32: Shaft and fitment key convention

Publication date:   Mar 16, 2012

General information

90.93 Standard confirmed   Jan 4, 2023


ISO/TC 108/SC 2 Measurement and evaluation of mechanical vibration and shock as applied to machines, vehicles and structures

International Standard

21.120.40   Balancing and balancing machines



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ISO 21940-32:2012 specifies one convention for balancing the individual components (shaft and fitments) of a keyed rotor assembly. This provides compatibility of all balanced components so that when they have been assembled the overall balance tolerance and/or vibration limit for the rotor assembly is met.
ISO 21940-32:2012 specifies that half-keys be used when balancing the individual components of a keyed rotor assembly. It also specifies a marking of the components balanced in accordance with the key convention used.
ISO 21940-32:2012 applies to rotors balanced in a balancing machine, in their own bearings or in situ. The key convention can also be applied when measuring the residual unbalance and/or vibration of rotors with keyways, but to which fitments have not yet been assembled.
In addition to applying to keys of constant rectangular or square cross-section mounted parallel to the shaft centreline, ISO 21940-32:2012 also applies to keys mounted on tapered shaft surfaces, to woodruff, gibhead, dowel and other special keys. The principle of the half-key convention is applied as is appropriate to the particular shape and location of the special key.

Life cycle


ISO 8821:1989


ISO 21940-32:2012
90.93 Standard confirmed
Jan 4, 2023