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ISO 8821 1st Edition, January 1, 1989
Complete Document
Superseded By: ISO 21940-32
Mechanical Vibration - Balancing - Shaft and Fitment Key Convention First Edition; (NZS/ISO 8821: 1989)
Additional Comments: ENGLISH * W/D S/S BY ISO 21940-32
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This International Standard specifies a single convention for balancing the individual components (shafts or rotors, and fitments) of a keyed assembly. It is intended to provide compatibility of all balanced components so that when they are assembled they will meet the overall balance and/or vibration tolerance levels for that assembly.

This International Standard requires that half keys be used when balancing the individual components of a keyed assembly to avoid the balancing errors created if full keys or no keys were used.

This International Standard applies to rotors balanced in balancing machines, in their own housings, or in situ. This key convention should also be applied when measuring residual unbalance and vibration severity of rotors utilizing keyways but to which the fitments have not yet been assembled.

Although the figures in this International Standard show keys of constant rectangular or square cross-section, mounted parallel to the shaft axis, this International Standard applies also to keys mounted on tapered shaft surfaces, to woodruff, gib, dowel and other special keys. The principle of the half-key convention as outlined in the definition and elsewhere is then applied as is appropriate to the particular shape and location of the special key.

This International Standard includes instructions for the implementation (see annex A) and for the transition period that will occur as the half-key convention is adopted