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ISO 21940-21 1st Edition, July 15, 2012 Mechanical vibration - Rotor balancing - Part 21: Description and evaluation of balancing machines
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Availability date: 07/13/2021
Description / Abstract:
This part of ISO 21940 specifies requirements for evaluating the
performance of machines for balancing rotating components by the
following tests:
a) test for minimum achievable residual unbalance,
Umar test;
b) test for unbalance reduction ratio, URR test;
c) test for couple unbalance interference on single-plane
machines;
d) compensator test.
These tests are performed during acceptance of a balancing
machine and also later, on a periodic basis, to ensure that the
balancing machine is capable of handling the actual balancing
tasks. For periodic tests, simplified procedures are specified.
Tests for other machine capacities and performance parameters,
however, are not contained in this part of ISO 21940.
For these tests, three types of specially prepared proving
rotors are specified, covering a wide range of applications on
horizontal and vertical balancing machines. An annex describes
recommended modifications of proving rotors prepared in acccordance
with ISO 2953:1985.
Moreover, this part of ISO 21940 also stresses the importance
attached to the form in which the balancing machine characteristics
are specified by the manufacturer. Adoption of the format specified
enables users to compare products from different
manufacturers.Additionally, in an annex, guidelines are given on
the information by which users provide their data and requirements
to a balancing machine manufacturer.
This part of ISO 21940 is applicable to balancing machines that
support and rotate rotors with rigid behaviour at balancing speed
and that indicate the amounts and angular locations of a required
unbalance correction in one or more planes. Therefore, it is
applicable to rotors with rigid behaviour as well as to rotors with
shaftelastic behaviour balanced in accordance with low-speed
balancing procedures. It covers both soft-bearing balancing
machines and hard-bearing balancing machines. Technical
requirements for such balancing machines are included; however,
special features, such as those associated with automatic
correction, are excluded.
This part of ISO 21940 does not specify balancing criteria; such
criteria are specified in ISO 1940-1 and ISO 11342 (only low-speed
balancing procedures apply).