BS ISO 21940-32:2012

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Half-key convention
5 Marking
6 Implementation of the half-key convention
Annex A (normative) - Specifications for the half-key
        convention
Annex B (informative) - Practical considerations for
        making half-keys and usage of keys
Annex C (informative) - Comparison between shaft and
        fitment key conventions
Bibliography

Describes one convention for balancing the individual components (shaft and fitments) of a keyed rotor assembly.

This part of ISO21940 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.

This part of ISO21940 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.

This part of ISO21940 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, this part of ISO21940 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.