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“The Right to Information, The Right to Live”

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“Knowledge is such a treasure which cannot be stolen”

“Invent a New India Using Knowledge”

है”ह”ह

IS/ISO 1925 (2001): Mechanical vibration - Balancing -Vocabulary [MED 28: Mechanical Vibration and Shock]

1S/1S0 1925:2001(Superseding IS 13274: 1992)

Indian Standard

MECHANICAL VIBRATION — BALANCING —VOCABULARY

ICS 21.120.40; 01.040.21

@ BIS 2007

BUREAU OF INDIAN STANDARDSMANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

Septen7ber2007 Price Group 11

Mechanical Vibration and Shock Sectional Committee, MED 28

NATIONAL FOREWORD

This Indian Standard which is identical with !S0 1925: 2001 ‘Mechanical vibration — Balancing —Vocabulary’ issued by the International Organization for Standardization (ISO) was adopted by theBureau of Indian Standards on the recommendation of the Mechanical Vibration and Shock SectionalCommittee and approval of the Mechanical Engineering Division Council.

This standard supersedes IS 13274:1992 ‘Mechanical vibration — Balancing — Vocabulary’

The text of ISO Standard has been approved as suitable for publication as an Indian Standard withoutdeviations. Certain conventions are, however, not identical to those used in Indian Standards.Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they shouldbe read as ‘Indian Standard’.

b) Comma (,) has been used as a decimal marker in the International Standards, while inIndian Standards, the current practice is to use a point (.) as the decimal marker.

In this adopted standard, reference appears to certain International Standards for which IndianStandards also exist. The corresponding Indian Standards, which are to be substituted in theirrespective places, are listed below along with their degree of equivalence for the editions indicated:

/nfernationa/ Standard Corresponding hdian Standard Degree ofEquivalence

ISO 2953: 1999 Mechanical vibration — lS/l SO 2953: 1999 Mechanical vibration IdenticalBalancing machines — Description and —Balancing machines — Descriptionevaluation and evaluation

ISO 11342 : 1998 Mechanical vibration lS/lSO 11342 : 1998 Mechanical do— Methods and criteria for the vibration — Methods and criteria for themechanical balancing of flexible rotors mechanical balancing of flexible rotors

Only the English text of the International Standard has been retained while adopting it as an IndianStandard, and as such the page numbers given here are not the same as in the InternationalStandard.

For the purpose of deciding whether a particular requirement of this standard is complied with, thefinal value, observed or calculated, expressing the result of a test or analysis, shall be rounded off inaccordance with IS 2 : 1960 ‘Rules for rounding off numerical values (revised)’. The number ofsignificant places retained in the rounded off value should be the same as that of the specified valuein this standard.

II1S/1S0 1925:2001

MECHANICAL

Scope

This International Standard establishes,

lndian Standard

VIBRATION — BALANCING —VOCABULARY

in Englishand in French, a vocabulary on balancing. An alpha-betical index is provided for each of the twolanguages.

A general vocabulary on vibration and shock is givenin ISO 2041.

NOTE Terms in boldface in the definitions are them-

selves defined elsewhere in this vocabulary.

Annex A gives an illustrated guide to balancing

machine terminology and includes equivalent terms inEnglish, French and German.

Normative references

The following normative documents contain provisionswhich, through reference in this text, constitute provi-sions of this International Standard. For datedreferences, subsequent amendments to, or revisionsof, any of these publications do not apply. However,parties to agreements based on this InternationalStandard are encouraged to investigate the possibilityof applying the most recent editions of the normativedocuments indicated below. For undated references,the latest edition of the normative document referredto applies. Members of ISO and IEC maintain regis-ters of currently valid International Standards.

ISO 2953, Mechanical vibration — Balancing ma-chines –– Description and evaluation.

ISO 11342:1998,Mechanical vibration — Methodsand criteria for the mechanical balancing of flexiblerotors.

1 Mechanics

1.1centre of massthat point associated with a body which has the prop-erty that an imaginary particle placed at this point witha mass equal to the mass of a given material system

has a first moment with respect to any plane equal tothe corresponding first moment of the system

[1s0 2041:1990, 1.31]

4.2principal inertia axescoordinate directions corresponding to tne principalmc)ments of inertia IX,,, (i = j)

NOTE 1 For each sef, of Cartesian coordinates at a given

point, the values of the six moments of inertia / ,,,, (i, j = 1,2,

3) of a body are in general unequal; for one such coordinate

system, the moments 1,,,, (i # j) vanish.

NOTE 2 The values of /,,,, (i= j) for this particular coor-

dinate system are called the principal moments of inertia

and the corresponding coordinate directions are called theprincipal inertia axes.

NOTE 3

I= J.~,.~i dm, if i + jr, r/

‘ =k2)d’~J’=jm

where

r2 =x12+x2 2 + X32

.x,, r, are’ Cartesian coordinates.

NOTE 4 If the point under consideration is the centre of

mass (1. 1) of the body, the axes and moments are called

central principal axes and central principal moments ofinertia, respectively.

NOTE 5 In balancing, the term principal inertia axis is

used to designate the central principal axis (of the threesuch axes) most nearly coincident with the shaft axis (2.7)

of the rotor, and is sometimes referred to as the balanceaxis or the mass axis.

1.3critical speedresonant speedcharacteristic speedis excited

at which resonance of a system

1

Fnr rmsonance, see ISO 2041:1990, 2.72. Also:.C)7E i .:::e ISO 2941:1990, 2.80 for undamped natural frequency.

‘. CITE 2. The evaluation of a critical/resonant speed willdepend on the measurement parameter used, such as dis-

~iacement, velocity and acceleration.

\,~T E :3 In the context of balancing, a critical;foeed~resonant speed relates to the once-per-revolution,c,xnponent of vibration.

‘f .4axis d rotation: stantaneous line about which a body rotates

:J7TE 1 H the bearings are anisotropic, there is noj:ali(-~r]iiry axis of rotation,

‘ml-: 2 In the case of rigid bearings, the axis of rotations I!-W shaft axis [2.7), but if the bearings are not rigid, the

.3.(s o! roiatic>n is not necessarily the shaft axis.

k? Rotor systems

;2.4rotorbmiy capable of rotation

:$OTE The term rotor IS sometimes applied to, forexample, a disk-like mass that has no journals (for example~1fly-wheel). In the sense of the definition 2.1, such a ~lsk-

ik.e mass becomes a rotor for the purpose of balancing(~ 11 only when it is placed on a shaft with journals (2.4)tnat can be supported by bearings.

2.2rigid rotorrotor (2. 1I whose deflection caused by a given unbal-

i+r!ce distribution is below acceptable limits at any

speed up 10 the maximum service speed

N(>TE A rotor which qualifies as a rigid rotor under oneset of conditions, such as service speed and initial unbal-arrce (3.1 1), might not qualify as rigid under other

conditmns

2.3

flexible rotorrotor (2.1) not considered to be rigid because of elas-hc deflection

2,4

journalt}i~t part of a rotor (2.1) which is supported

and/or gu!ded by a bearing in which it rotates

:2

radially

2.5journal axismean straight line joining the centroids of cross-sectional contours of a journal (2.4)

2.6journal centreintersection of the journal axis (2.5) and the radialplane of the journal (2.4) where the resultant trans-verse bearing force acts

2.7shaft (rotor) axisstraight line joining the journal centres (2.6)

2.8inboard rotortwo-journal rotor (2.1 ) which has its centre of mass(1.1 ) between the journals (2.4)

NOTE For a precise description of the rotor, it may benecessary to state positionsof the centre of mass and of thecorrection planes (4.8).

2.9outboard rotortwo-journal rotor (2.1 ) which has its centre of mass(1.1) located other than between the journals (2.4)

NOTE See note to 2.8.

2.9.1overhunglocation outside bearing span

EXAMPLES Overhung mass, overhung correctionplane.

NOTE See note to 2.8.

2.10perfectly balanced rotorideal rotor (2. 1) which has zero unbalance (3.1)

2.11mass eccentricitydistance between the centre of mass (1.1) of a rigidrotor (2.2) and the shaft axis (2.7)

NOTE See also 3.15.

2.12local mass eccentricityfor small axial elements cut from a rotor (2.1) per-pendicular to the shaft axis (2.7), the distance of thecentre of mass (1.1) of each element from the shaftaxis

HISO 1925:2001

2.13bearing supportpart, or series of parts, that transmits the load fromthe bearing to the main body of the structure

2.14foundationstructure that supports the mechanical system

NOTE In the context of the balancing (4.1) and vibra-

tion of rotating machines, the term foundation is usually

applied to the heavy base structure on which the whole ma-chine is mounted.

2.15quasi-rigid rotorflexible rotor (2.3) that can be satisfactorily balancedbelow a speed where significant flexure of the rotoroccurs

2.16balancing speedrotational speed at which a rotor (2.1) is balanced

2.17service speedrotational speed at which a rotor (2.1) operates in itsfinal installation or environment

2.18slow-speed runoutrunout measured on a rotor (2.1) surface at a lowspeed; i.e. a speed where no significant vibration oc-curs caused by unbalance (3.1)

NOTE 1 The once-per-revolution component of slow-

speed runout is often measured so that it can be subtractedvectorially from a subsequent measurement taken on the

same surface at a higher speed to isolate the component ofthe measurement caused by unbalance.

NOTE 2 A slow-speed runout may contain mechanical

and electrical components.

2.19electrical runoutcertain errors which may be introduced into runoutmeasurements when using non-contacting sensors

NOTE Such errors can arise from residual magnetismor electrical inhomogeneity in the measured component or

other effects which affect the calibration of the sensor.

2.20total indicated runoutdifference between the maximum and minimumvalues of the radii of the boundary of a planar surface,when they are measured from a fixed axis of rotation(1 .4) normal to the plane

2.21fitmentcomponent without its own shaft which has to bemounted on a shaft or mandrel (8.2) so that its un-balance (3.1 ) can be determined

EXAMPLES Couplings, pulleys, pump impellers, blowerfans and grinding wheels.

2.22isotropic bearing supportbearing support (2.13) having the same dynamiccharact-eristics in any radial dire&ion

2.23spigotrabbetpilottype of interface used in the couplingcomponents to maintain concentricity

2.24half-kev

of rotor (2.1)

key use~ in balancing, having the unbalance (3.1)value of the portion of the final (full) key which willoccupy either the shaft keyway or the fitment keywayin the final assembly

NOTE 1 The unbalance value of the half-key for a given

shaft can differ from that needed for the mating fitment forequal keyway length owing to differences in distance fromthe shaft centreline, depth of keyways and clearances.

NOTE 2 The required unbalance value for a half-key

may be calculated by assuming that the full key is separatedinto two half-keys along the contoured parting line between

shaft and fitment, taking half the height clearances of keyand keyway in each of the key halves into consideration(see Figure 1).

3

i!3/K3Q ‘!925 :2001

1

●

iiey

}{alf-key for fiment

,’ Halfk,ev fo! shaft

3 Unbalance

,an-r~ The definitions in

:tors They may also apply‘Iause 5

3.4

unbalance

Figure 1 — Contoured half-key set

this clause apply to rigidto flexible rotors, but see

~,cjrlc!,~lor! whlc~l exists in a rotor (2.1) when vibration

fcrce or motion is imparted to its bearings as a result

~f centrltugal fc]rces

‘J(JTE 1 See the note above.

‘J:)TE: 2 The term unbalance is sometimes used as a

vnonvm, for amount of unbalance (3.3), or unbalance

vector (3.5).

‘JOT E 3 The term imbalance is sometimes used in place,f :]nbalance, but this is deprecated.

NC-17-E4 Unbalance will, in general, be distributed

ihrc.]ghout the rotor but can be reduced to

~~j resultant unbalance (3.12) and resuftant momentunbalance (3.13), described by three unbalance vec-tors in three specified planes, or

~}; dynamic unbalance (3.9), described by two unbal-ance vectors In two specified planes.

3.2unbalance massmass whose centre is at a distance from the shaftaxis (2.7)

3.3amount of unbalanceproduct of the unbalance mass (3.2) and the dis-tance [radilJS) of its centre of mass (1 .1) from the

shaft axis (2.7)

NOTE Units of amount of unbalance are gram milli-

metres (grnm).

3.4angle of unbalancepolar angle at which an unbalance mass is locatedwith reference to the given rotating coordinate system,fixed in a plane perpendicular to the shaft axis (2.7)and rotating with the rotor (2.1 )

3.5unbalance vectorvector whose magnitude is the amount of unbalance(3.3) and whose direction is the angle of unbalance(3.4)

3.6static unbalancecondition of unbalance (3.1) for which the centralprincipal axis (1.2) is only displaced parallel to theshaft axis (2.7)

a1S/1S0 1925:2001

3.7quasi-static unbalancecondition of unbalance (3.1) for which the centralprincipal axis (1 .2) intersects the shaft axis (2.7) ata point other than the centre of mass (1 .1)

3.8couple unbalancecondition of unbalance (3.1) for which the centralprincipal axis (1 .2) intersects the shaft axis (2.7) atthe centre of mass (1 .1)

NOTE The quantitative measure of couple unbalance

can be given by the vector sum of the moments of the twodynamic unbalance (3.9) vectors about a reference pointon the shaft axis.

NOTE 2 If static unbalance (3.6) m a rotor (2.1) iscorrected In any single plane other than that containing thereference point, the couple unbalance will be changed.

NOTE 3 Units of couple unbalance are gram milllmetres

squared (g mmz; I.e. g mm. mm) wherein the second lengthdimension refers to the distance between the measuring

planes.

3.9dynamic unbalancecondition in which the central principal axis (see 1.2)

has any position relatwe to the shaft axis (2.7)

NOTE 1 In special cases N may be parallel to or may

Intersect the shaft axis.

NOTE 2 The quantltatwe measure of dynamic unbalance

can be gwen by two complementary unbalance vectors

(3.5) m two speclf!ed planes (perpendicular to the shaft axis)wh!ch completely represent the total unbalance (3.1) of therotor (2. 1).

3.10residual unbalancefinal unbalanceunbalance (3.1) of any kind that remains after

balancing (4.1 )

3.11initial unbalanceunbalance (3.1) of any kind that exists in the rotor(2.1) before balancing (4.1)

3.12resultant unbalance(‘rvector sum of all unbalance vectors (3.5) distributedalong the rotor (2.1)

NOTE See notes to 3.13

3.13resultant moment (couple) unbalancefrvector sum of the moments of all the unbalance vec-tors (3.5) distributed along the rotor (2.1) about theplane of the resultant unbalance (3. 12)

NOTE 1 The resultant unbalance together with the re-

sultant moment (couple) unbalance describe the unbalancestate of a rigid rotor (2.2) completely.

NOTE 2 The resultant unbalance vector IS not related to

a parbcular radial plane, but the amount and angular dlrec-

tlon of the resultant moment (couple) unbalance depends on

the axial Iocatlon chosen for resultant unbalance.

NOTE 3 The resultant unbalance vector IS the vector

sum of the complementary unbalance vectors of thedynamic unbalance (3.9).

NOTE 4 The resultant moment (couple) unbalance isoften expressed as a pair of unbalance vectors of equal

magmtude, but opposite directions, m any two differentradial planes.

3.14unbalance coupleresultant couple of the system of centrifugal forces of

all mass elements of the rotor (2,1) for the casewhere the resultant unbalance force is zero

3.15specific unbalance(

amount of static unbalance (3.6) divided by themass, IrI, of the rotor (2.1)

NOTE 1 The speclflc unbalance IS numerically equiv-alent to the mass eccentricity (2.1 1).

NOTE 2 In the case of a rotor with two correctionplanes (4.8), speclflc unbalance sometimes refers to the

unbalance (3.1) in one plane divided by the rotor mass

allocated to that plane according to its mass distribution.

3.16balance quality grade(rigid rotors) measure for classification wh)ch IS the

product of the specific unbalance (3,15) and themaximum service angular velocity of the rotor (2.1),expressed in mlllimetres per second

NOTE See ISO 1940-1

3.17controlled initial unbalanceinitial unbalance (3.1 1) which has been mlnimlzedby individual balancing (4.1) of components and/orcareful attention to design, manufacture and assemblyof the rotor (2.1)

5

UMSC3 ‘1925:2001

4 !&dancing

4.4

h.aiancing:,IFJcedure by which the mass distribution of a rotor

~ 11 IS checked and, if necessary, adjusted to ensureI I -tf the residual unbalance (3.1 O) or the vibration of

.’P journals (2.4) and/or forces on the bearings at a‘ tt+~tier>cy corresponding to service speed (2.1 7) are“):~’?!r-~specified limits

4.2single-plane balancingstatic balancing!;. ocedurw by which the mass distribution of a rigidrotor (2.2) is adjusted to ensure that the residual

resultant unbalance (3.1 2) is within specified limits

4.3

two-plane balancingdynamic balancingcwcedure by which the mass distribution of a rigidrotor (2.2) is adjusted to ensure that the residual

dynamic unbalance (3.9) is within specified limits

4$,.4

indexing unbalance:Ifinge in unbalance (3.1) indicated after indexing;~. 15) two components of a rotor assembly in relation::. aach otner, which is usually caused by individual.:[’mponent unbalance, runout of mounting (locating)<urfaces ancUor loose fits

b\j ::,,~.: Given the repeatability of the interface fit, the

;k:onge m unbalance measured in one component after,-+x!ng by 180” is twice the error in, or resulting from, the

--;a*I:Ig component.

45

method of correction;“(”mdure by which the mass distribution of a rotor;.”.I ~ IS ad)usted to reduce unbalance (3.1 ), or vibra-:Ii~n due to unbalance, to an acceptable value

~“ “: i-:: Corrections are usually made by adding~,?:erial lo, or remowng it from, the rotor.

4.6

component correction;{ j;rection of unbalance (3.1) in a correction plane;<.8} at three or more of a predetermined number ofz!llgular locations

~,~

polar correction;I}rrection of amount of unbalance (3.3) in a CorreC-i?on plane (4.8) at a single angular location

4.8correction planebalancing planeplane perpendicular to the shaft axis (2.7) of a rotor(2.1 ) in which correction for unbalance (3.1) is made

4.9measuring planeplane perpendicular to the shaft axis (2.7) in whichthe unbalance vector (3.5) is determined

4.10reference planeany plane perpendicular to the shaft axis (2.7) towhich an amount of unbalance (3.3) is referred

4.11test planeplane perpendicular to the shaft axis (2.7) of a rotor(2.1 ) in which test masses (4.20) maybe attached

4.12acceptability limitthat value of an unbalance parameter which is speci-fied as the maximum below which the state of un-balance (3.1 ) of a rotor (2,1) is considered to beacceptable

4.43balance tolerancepermissible residual unbalance

[per(rigid rotors) that amount of unbalance (3.3) with

respect to a plane [measuring plane (4.9) or correc-

tion plane {4.8)] which is specified as the maximum

below which the state of unbalance (3.1) is consid-

ered to be acceptable

4.14field balancingprocess of balancing (4.1) a rotor (2.1) in its ownbearings and supporting structure rather than in abalancing machine (5.1 )

NOTE Under such conditions, the information required

to perform balancing is derived from measurements ofvibratoly forces or motions of the supporting structureand/or measurements of other responses to rotorunbalance (3.1 ).

4.15indexingincremental rotation of a rotor (2.1), or part of a rotorassembly, for the purpose of bringing it to a desiredposition

..

1S/1S0 1925:2001

4.16mass centring~JrOct?ss of determination of the pritICipal aXiS of in-ertia (1 .2I of a rotor (2.1 ) followed by the machlmncjof journals (2,41, cerltres or other reference surfaces

to bring The axis of rotation (1 .4), determmed by!hese surfaces, Into close proxlmlty with the pnnclpalaXi S

4.17correction massmass attached to a rotor (2.1 ) in a gwen correctionplane (4.8) for the purpose of reducing the un-balance (3.1 ) to the des!red level

NOTE The same correction can be effected by

removing mass from the opposite side of the rotor.

4.18calibration massknown mass used

a) In con)unctlon with a proving rotor (8.8) to call-brate a balancing machine (5.1), and

b) on the first rotor (2.1) of a kind to calibrate a

soft-bearing balancing machine (5.8) for that

parhcular rotor and subsequent identical rotors

4.19trial massmass selected arbitrarily [or by prior experience with

similar rotors (2.1 )] and attached to a rotor to deter-mine the rotor response

NOTE A trial mass IS usually used In “tnal-and-errot’

balancing (4 1) or field balancing (4 14) where condlhons

cannot be precisely controlled and/or precls!on measuringeqolpment IS rot available.

4.20test massoreclsely defined mass used in conjunction wlttr a

proving rotor (8.8) to test a balancing machine(5.1 )

NOTE 1 ‘rhe use of the term “test weight” IS deprecated;

the term ‘lest mass” IS accepted In mternatlonal usage.

NOTE 2 The speclflcatlon for a test mass should include

Its mass and the Iocatlon of Its centre of mass (1.1): the

aggregate effect of the errors In these values should nothave a signlftcant effect on the test results.

4.21differential test massestwo masses, representing different amounts of un-balance (3.3), added to a rotor (2.1) in the same

transverse plane at dtametrlcally opposed positions

NOTE Differential test masses are used, for example,In cases where a stngle test mass (4.20) is Impractical.

4.22differential unbalancedifference in unbalance (3.1) between the two differ-ential test masses (4.21)

4.23index balancing(multlparf rotor assemblies) procedure whel by each

part clf a multlpart rotor assembly is corrected within

itself for the unbalance (3.1) errors in It, and caused

by it, by indexing one part of the assembly with

rescrect to the remainder

NOTE: [f 180° indexing IS not possible, other anglescan be used: in that case, however, vector calculation might

be required.

4.24

vibration transducer planeplane perpendicular to the shaft axis (2.7) In which

the wbration transducer is located

4.25progressive balancingmethod by which one or two components are added

to a balanced shaft, the unbalance (3.1) of the as-sembly being then corrected for the component(s)

NOTE 1 The next set of components is then added andthe entire assembly is again corrected for the last added setof components, until the assembly is completed.

NOTE 2 Th!s procedure is somebmes called “balance-as-yo~J-build”.

4.26plane transpositionprc}cess of determining the unbalance (3.1) values in

planes other than where they were initially measured

4.27trim balancingcorrection of small residual unbalances (3.10) in arotor (2.1 ), often in situ

4.28quarter pointsterm used to describe the positions of the optimum

correction planes (4.8) in balancing a flexible rotor(2.3) at low speed by procedure F in accordance with1S0 11342:1998

●

7

iS/lSO 1925: 2001

5 Balancing machines and equipment

:;et’ 1s(12!35:3.

5.1

balancing machine,,-lCl~h,r]e ttlat provides a measure of the unbalance

::~ I } n a rotor (2. I ) and which can be used for ad-

jsI~IIq the mass distribution of that rotor mounted on

+ so ~hat the cnce-per-revolution vibratory motion of

:’-ie journals (2,4) or the force on the bearings can be

‘educed If necessarv

5.2

gravitational balancing machinenon-rotational balancing machinebalancing machine (5.1 ) that provides

POfl of a rigid rotor (2.2) underI ondltlons and provides information on

‘w:~ ang’e of the static unbalance (3.6),,

5.3

centrifugal balancing machinerotational balancing machine

for the sup-

non-rotating

the amount

balancing machine ~5.1) that provides for the‘,upport ~nd rctahon of a rotor (2.1) and for the,Yle:]surt?rnent cf once-per-revolution vibratory forces

cr motmrs due to unbalance (3.1) in the rotor

5.4

single-plane balancing machinestatic balanctng machine

gravitational (5.2) or centrifugal balancing ma-chine (5.3) that provides information for

accompllshjng single-plane balancing (4.2)

‘iOTE Smglc+plane balancing can be earned out on a

; llr of knife edges without rotation of the rotor but is now~)ure usually earned out cm centrifugal balanclng machines

5.5

two-plane balancing machinedyIIam Ic balanctng machine

centrifugal balancing machine (5,3) that furnishesP+ormatlon for performing two-plane balancing (4.3)

PJOTE Two-plane balancing machines are somettmes[JCCI to accomplish single-plane balancing (4.2).

5.6

hard-bearing balancing machineforce-measuring balancing machine

k]elow-resonance balancing machine

balancing machine (5.1 ) having a balancing speed(2. 16) range below the natural frequency of the sus-

pension-and-rotor system

5.7resonance balancing machinebalancing machine (5.1) having a balancing speed(2.1 6) corresponding to the natural frequency of the

suspension-and-rotor system

5.8soft-bearing balancing machineabove-resonance balancing machine

balancing machine (5.1 ) having a balancing speed(2.1 6) above the natural frequency of the suspension-and-rotor system

5,9compensating balancing machinenull-force balancing machine

balancing machine (5.1) with a built-in calibrated

force system which counteracts the forces due to un-balance (3.1 ) in the rotor (2.1)

5.10direct-reading balancing machinebalancing machine (5.1 ) which can be set to indicate

unbalance (3.1) in terms of angular position and inunits of mass, such as grams, in any two measuringplanes (4.9) without significant correction planeinterference (5.25) and without requiring individualcalibration (5.34) for the first rotor (2.1 ) of a kind

5.11swing diametermaximum workpiece diameter that can be accom-

modated by a balancing machine (5.1)

5.12field balancing equipmentassembly of measuring instruments for providing in-

formation for performing balancing (4.1) operationson assembled machinery which is not mounted in abalancing machine (5.1)

5.13amount indicator(on a balancing machine) dial, gauge or meter used to

indicate the amount of unbalance (3.3) or the effectof this unbalance (3.1)

1S/1S0 1925:2001

5.14practical correction unitJr- i ccres~mn:i[rlg tc a unit value of the amount ofunbalance (3 3) Indicated on a balancing machine(511

5.15counterweightL“Vt’1 j~lf <ldf)C’[j :C a body to reduce a calculated

unbalance {? 1 ) at a desired place

NOT: SLIC”I wwghts can be Wed to bring an asym-mc!r)( [Iody tO a state of balance or to reduce bending

mcn~ot-!f, Lvfhln I body, for example crankshafts

5.16compensatorf,l{;llltl, !u,lt ,rlt(; a balancing machine (~. f) ~hlch en-,IbI<JS!}]e initial unbalance (3.1 1) of the rotor (2,1) to

be nulled OUI, usually electrically, so speeding up the

pr{!ces= of plane setting (5.35) and calibration (5.34)

5.17angle indicatordevice [~sed to indicate the angle of unbalance (3.4)

5.18sensitivity switchcontro[ used to change the maximum amount of un-balance (3.3) that can be Indicated In a range or

scale, usually n steps of 10:1 or smaller

5.19angle reference generator(balanclng device used to generate a signal which

defines the angular poslflon of the rotor (2.1)

5.20angle reference marksmarks placed on a rotor (2.1 ) to denote an angle ref-

erence system fixed in the rotor

NOTE They may be optical, magnetic, mechanical orradloact)ve

5.21vector measuring devicedevice for measuring and displaying the amount ofunbalance (3.3) and angle of unbalance (3.4) in

terms of an unbalance vector (3.5), usually by

means of a Doint or line

5.22component measuring devicedevice for measuring and displaying the amount ofunbalance (3,3) and angle of unbalance (3.4) interms of selected components of the unbalance

vector (3.5)

5.23balancing machine minimum responsemeasure of the machine’s ability to sense and indicate

a rmnlmum amount of unbalance (3,3) under speci-

fied conditions

5.24balancing machine accuracyilmlts wkh~n which a gwen amount of unbalance(3.3) and angle of unbalance (3.4) can be measured

under speclfled conditions

5.25correction plane interferencecross-effectchange in balancing machine (5.1 ) indication for onecorrection plane (4.8) of a gwen rotor (2.1), whtch IS

observed for a certain change in unbalance (3.1) in

the other correction plane

5.26correction plane interference ratiosIA,B and IBA

]nterierence ratios of two

A and B of a given rotorfollowlng relationships:

where ( AB and ( ‘gB are

correction planes (4.8)(2,1) are defined by the

the unbalance readings

referring to planes A and B respectively, caused by

the addition of a specified amount of unbalance (3.3)in Plane B; and

where (JIBA and [JAA are the unbalance readings refer-

ring to planes B and A respectwely, caused by the

addition of a specified amount of unbalance in plane A

NOTE 1 The correction plane Interference ratio for a

balancing machine (5.1 ) on which the plane separation(5.28) has been carefully adjusted should be a mmimum.

NOTE 2 The ratio is usually given as a percentage.

9

1S/1S0 1925:2001

5.27couple unbalance interference12(

ratio

l;~erference ratio defined by the relationship:

I cj~, /’s /(’c

V,F I-re ( s IS the change In static unbalance (3.6) in-:: L.itIon of a balancing machine (5.1) when a given;{r~}ount of couple unbalance (3.8) [’c is introduced

17trj the rotor (2,1 )

?,: , -r-r- I-hls ratio is generally used m the testing of

s!ngle-plane balancing machines (5.4) and may be

~ <r,cssecl as a percentage by multlplytrrg It by the maxi-,.,~:~ CIIStanCe between the test planes (4.1 1) on a prOVing

rotor (8 8

5.28plane separation~:: :~blhty of a balancing machine (5.1) to minimizeII, correction plane interference ratio (5.26)

p,(:,-~ This term IS also used for the related process

5.29balancing machine sensitivityI,<,renlent In unbalance (3,1) [ndlcatlon of a balanc-ing machine (5.1 ) under speclfled conditions,txfressed as Indicator movement or a dtgltal reading

;Itr Llnl~ increment In the amount of unbalance (3.3)

5.30plane separation networknodal network. II !{nc,w clrcult, Interposed between the motion

‘ il,5d LJCerS and the unbalance Indicators, that per-

‘ tws the plane separation (5.28) function electrically,ti,rtout requlrlng particular locations for the motiont’i:l\dLJCf?r S

5.31parasitic mass!il, inclng mactune) any mass, other than that of the

rotor ~? 1 ) being balanced, that IS moved by the un-

~b,i!,~nce force(s) developed In the rotor

5.32permanent calibration‘~ ~:ure of a hard-bearing balancing machine (5.6)

:~i~ pt?rmlts It to be calibrated once and for all, so that

I: remains calibrated for any rotor (2.1) wlthln theL:apaclty and speed range of the machine

rJorF ~he machine should be capable of being set for,Ilf+f:rcrlt rotor dlrnenslons (see 5.35)

5.33unbalance reduction ratioURRratio of the reduction in the unbalance (3.1) by asingle unbalance correction to the initial unbalance(3.11):

URR =[Jl –[J2 ~l_Q

[J, [J,

where

[/1 is the amount of intial unbalance;

(2 is the amount of unbalance (3.3) remaining

after one correction.

NOTE 1 The unbalance reduction ratio is a measure ofthe overall efficiency of the unbalance correction,

NOTE 2 The ratio IS usually given as a percentage.

5.34calibrationprocess of adjusting a machine so that the unbalance

!ndlcator(s) read(s) in terms of selected correction

units in specified correction planes (4.8) for a givenrotor (2.1 ) and other essentially identical rotors

NOTE It may include adjustment for angular Iocatlon ifrequtred.

5.35setting(hard-bearing balancing machine) operation of enter-

ing into the machine Information concerning the

location of the correction planes (4.8), the location of

the bearings, the radii of correction, and the speed if

applicable

5.36

mechanical adjustment(balancing machine) operation of preparing the

machine mechanically to balance a rotor (2.1)

5.37self-balancing deviceequipment which compensates automatically for

changes in unbalance (3.1) during normal operation

5.38minimum achievable residual unbalance[ ‘“,a,smallest value of residual unbalance (3.10) that abalancing machine (5.1 ) is capable of achieving

‘(

1S/1S0 1925:2001

539minimum achievable residual specific

unbalancel’~~~smallest value of residual specific unbalance (3.15)that a balancing machine (5.1) is capable of achiev-ing under given conditions

5.40claimed minimum achievable residual

unbalance(1mar, clvalue of minimum achievable residual unbalance(5.38) stated by the manufacturer for his machine,and measured in accordance with the procedurespecified in ISO 2953

5.41measuring run(on a balancing machine) procedure to obtaininformation on unbalance (3.1) correction, mainlyconsisting of the following steps:

a)

b)

c)

d)

e)

f)

9)

mechanical adjustment of the machine, including

the drive and tooling;

setting of the indicator system;

preparation of the rotor (2.1);

any other required operation, for example, safety

measures;

acceleration of the rotor;

collection and evaluation of measured data;

deceleration of the rotor

NOTE 1 For subsequent runs of the same rotor, steps

a), b) and c) are omitted.

NOTE 2 For the next rotor of the same type, steps a)

and b) are omitted.

NOTE 3 A measuring run without a subsequent correc-

tion is sometimes referred to as a check run or audit run.

5.42

balancing run(on a balancing machine) run consisting of onemeasuring run (5.41 ) and the associated correctionprocess

5.43floor-to-floor timetime necessary, for all balancing runs and measuring

runs, for loading and unloading, to balance one rotor(2.1 ) to within tolerance

NOTE 1 Floor-to-floor time IS expressed In hme perpiece, using an appropriate unit of time, for example,seconds, minutes, hours or days.

NOTE 2 If a balancing machine contains more than onerotor at a time (e.g. transfer machines), the time betweenone rotor and the next, both leaving the machine, is used.

NOTE 3 If the floor-to-floor time varies from rotor to rotor,the arithmetic mean value may be used.

NOTE 4 Calculated for a longer period (e.g. one year),

time for tool change, maintenance and others may be m-included. In this case it is called floor-to-floor time gross.

5.44cycle ratenumber of starts and stops that a balancing machine(5.1 ), for a given rotor (2.1) having a specified mo-ment of inertia and for a given balancing speed(2.16), can perform per hour (without damage to themachine) when balancing the rotor

5.45production ratereciprocal of floor-to-floor time (5.43)

NOTE 1 Production rate is stated in pieces per time,

using longer time intervals, for example, hour, shift, day oryear

NOTE 2 In the case of floor-to-floor time gross, theproduction rate gross is obtained.

5.46traverse testtest by which the residual unbalances (3.1 O) of a

rotor (2.1 ) can be found (see ISO 1940-1) or withwhich a balancing machine (5.1) may be tested forconformance with the claimed minimum achievableresidual unbalance (5.40), Umar (see ISO 2953)

5.47vertical axis freedomfreedom of the beating carriage or housing of a hori-zontal balancing machine (5.1) to rotate by a few

degrees about the vertical axis through the centre ofthe support

11

1S/1S0 1925:2001

5.48bob weightafi,achment to the crankshaft pms during balancing(4.1 ) to simulate part of the rotating and reciprocating

mass of the piston/connectlrrg rod assembly

5.49phantom unbalance indicationfalse unbalance (3.1 ) indication resultlng from once-per-revolution .sIgnals produced by conditions otherthan unbalance

NOTE 1 Phantom unbalance Indlcahon can be causedby lack of verbcal freedom (see 5.47) when balanclng In~Ieeve or rolllng element bearings, by a blndrng urmversal

Iolrit In a Car(Jan shaft. by alternating bearing forces causedby a bent rotor shaft, by rotating magnetic fields or other

slmllar conditions,

NCITE 2 For rigid rotors (2.2), the phantom unbalance

Indlcatlon may be separated from the unbalance Indlcatmnby observing the change In Indlcatlon at different balancingspeeds (f’ 16)

5.50double compensatorfacliity built Into a balancing machine (5.1) whicheltrn[nates the effects on the unbalance (3.1) indica-

tion of systematic errors caused by tooling

5.51balancing bearingsslave bearingsspecial rolllng element bearings, often having reducedclearance, for supporting a rotor (2,1) In a low-speedbalancing machine (5.1 )

NOTE Slave (balancing) bearings are prlrnanly usedfor jet engine rotor balancing because the large clearancesIn cold engine bearings (which accommodate expansion at

service temperatures) can cause significant random

balancing (4 1) errors

6 Flexible rotors

6.1(rotor) flexural critical speedspeed of a rotor (2.1) at which there is maximum

flexure of the rotor and where that flexure IS signifi-cantly greater than the mohon of the journals (2.4)

6.2rigid-rotor-mode critical speedspeed of a rotor (2.1) at which there is maximummotion of the journals (2.4) and where that motion is~:gnlflcantly greater than the flexure of the rotor

6.3(rotor) flexural principal modefor undamped rotor/bearing systems, that modeshape which the rotor takes up at one of the (rotor)flexural critical speeds (6.1)

6.4multilane balancingany balancing procedure, applied to the balancing(4.1 ) of flexible rotors (2,3), that requires unbalance(3,1 ) correction in more than two correction planes(4.8)

6.5modal balancingprocedure for the balancing (4.1 ) of flexible rotors(2.3) in which unbalance (3.1) corrections are madeto reduce the amplitude of vibration in the separatesignificant flexural principal modes (6.3) to withinspecified limits

6.6,lth modal unbalance

unbalance (3,1) which affects only the nth principalmode of the deflection configurahon of a rotor/bearingsystem

NOTE 1 A measure of this component of unbalance is

given by

where ~;(:) is the eccentricity of the local rmass centre at

point : along the rotor.

NOTE 2 The ,lth modal unbalance is not a single un-balance but an unbalance distribution in the ~lthmode

It can be mathematically represented with respect to its ef-

fect on the nth principal mode by the single unbalance vector

[;,, as

o[.J()@ 2

=&,, ,U: ,,

0

;)d: = ,;,,,,,,, = u,,

12

1S/1S0 1925:2001

6.7equivalent ~lthmodal unbalance

mln!mum single unbalance, (j),e, equivalent to the }r~h

modal unbalance (6.6) in its effect on the nth princi-

pal mode of the deflection configuration

NOTE 1 There exwts the relatlon {;,, = [~,,e 0,, (:C ),

where L>,,(.-c I IS the mode function value for : = :C, the

axial coordinate of the transverse plane where ~;,,e IS

applled

NOTE 2 A set of masses distributed in an appropriate

number of correction planes (4 8) and so proportioned that

the mode under consideration WIII be affected, may be

called the equivalent II!h modal unbalance set.

NOTE 3 An equivalent ~I:t’ modal unbalance WIII affect

some MO(W! other than the fill mode

6.8modal balance toleranceamount of equivalent modal unbalance in a mode that

IS speclfled as the maximum below which the state of

unbalance (3.1) In that mode IS considered to beacce~table

6.9multiple-frequency vibrationvibration at a frequency corresponding to an Integral

multlple of the rotational frequency

NOTE This vibrat[on may be caused by anrsotropyof the rotor (2.1 ), non-l !near characteristics of the

rotorbearlng system, or other causes.

6.10thermally induced unbalancechange In condition exhlblted by a rotor (2.1) If Itsstate of unbalance (3.1) is significantly altered by itschanges in temperature

NOTE The change in condition can be permanent or

temporarv.

6.11low-speed balancing(flexible rotors) procedure of balancing (4.1) at aspeed where the rotor (2.1 ) to be balanced can beconsidered to be rigid

6.12high-speed balancing<flexlble rotors) procedure of balancing (4.1) at a

speed where the rotor (2.1 ) to be balanced cannot beconsidered to be ngld

6.13susceptibility to unbalanceindication of the likelihood of a machine having a

significant change of unbalance (3.1) over a certain

period of operation

6.14sensitivity to unbalancemeasure of the change in vibration response of a

machine to a change of unbalance (3.1)

NOTE It IS expressed numerically as the magmtude ofthe ratio of the vector change of wbration to a vector changeof unbalance.

6.15local sensitivitymagnitude of the ratio of the change of the displace-

ment or velocity vector in a specified measuring

plane (4.9) to the change of the unbalance (3.1) in a

spectfled plane in the rotor (2.1) at a specified speed

NOTE The local sensitwity is frequently referred to asthe “influence coefficient”. It is a dimensional quantity.

6.16mode function@,I(:)mathematical expression for the deflection shape of

the rotor (2.1 ) in the corresponding mode

NOTE In deriving the definitions 6.6 and 6.17 to 6.22 of

modal terms, it is assumed that the normal modes are or-thogonal and the system is axially symmetric.

6.17modal mass

)1111scaling factor with dimensions of mass, used in par-l to

describe the mode function (6.1 6) and expressed by

where ,11(:) IS the mass per unit length of the rotor(2, 1) and [. is the rotor length

6.18modal amplifaction factorM,,ratio of the magnitude of the modal vibrationdisplacement vector to the magnitude of the modaleccentricity

13

J1S/1S0 1925:2001

NOTE It IS a non-dimensional quantity. It is expressedfot the ,1111mode as

Jj IS the rotational angular frequency;

((J, IS the undamped natural angular frequency;

>, IS the modal damping ratio (6.21)

6.19modal sensitivitymagnitude of the ratio of the change of the amount of

the modal displacement vector to the change of theamount of the modal eccentricity [modal unbalance(3 1)dlwded by modal mass]

NOTE 1 It IS a non-dimensional quantity

NOTE 2 In practical determinations of modal sensitivity,care should be taken to extract the relevant modal compo-nents

NOTE 3 The modal sensitiwty for the ,lth mode is equalIn rnagmtude to the modal amplification factor (6,9), M,,.

6.20non-dirnensional speed (~lthmode)

ratio of the shaft speed to the corresponding critical

speed [resonant speed], i.e. fl/cti,l

NOTE It IS sometimes expressed as ~,,

6.21modal damping ratio,-$,,measure of the damping effect on the nth mode

NOTE The damping in the nlh mode is sometimes ex-pressed in terms of the factor Q,,, which is the value of the

modal amplification factor (6.9) for J2/0,1 = 1. That is

s,,=&

6.22modal eccentricityspecific modal unbalance

(llth mode) )lth modal unbalance (6.6) divided by the

~lth modal mass (6.17)

7 Rotating rigid free-bodies

The definitions in this clause apply to rotating rigid

free-bodies. However, when such a body is mountedon a balancing machine, it can be considered as arotor, and in this case the definitions in clauses 1 to 5may be used.

7.1rigid free-bodysystem of particles with rigid internal connections andno external constraints

7.2rotating rigid free-bodyrigid free-body (7.1 ) rotating about an axis

NOTE The rotation axis is not stationary if it is not acentral principal axis.

7.3principal axis locationaxis location defined by the offset of the centr< ofmass (1.1 ) from the design axis (7.4) and the tiltangles of the principal axis from the design axis

7.4design axisaxis about which parts and assembliesand about which it is intended thatbalanced

are designedthe body be

NOTE In the ideal case, the design axis and spin axis

coincide,

7.5rigid free-body unbalance(balancing machme) condition that exists in anyrotating rigid free-body (7.2) when rotary motion isimparted about its spin axis as a result of centrifugalforce(s)

NOTE 1 The rotation motion of the principal axis may be

cylindrical or conical, or a combination of both.

NOTE 2 The definitions of rigid free-body static unbal-

ance, rigid free-body couple unbalance and rigid free-body

14

1S/1S0 1925:2001

dynamic unbalance are the same as defmihons 3.6, 3.8 and3.9 except that the spin axis is used here as a referenceaxis Instead of the shaft axis (2.7).

7.6rigid free-body balancingprocedure by which the mass distribution of a rigidfree-body (7.1 ) is checked and, If necessary, ad-

justed to ensure that the principal axis location (7.3)

IS within specified limits

8.4bias massmass added to a mandrel [balancing arbor] (8.2) to

create a desired unbalance bias (8,3)

8.5master rotorcalibration rotor (8,7) with provision for adding cali-

bration masses (4.1 8) at a known location and usedfor periodically checking the calibration (5,34) of abalancing machine (5.1)

8 Balancing machine tooling●

8.1dummy rotor,balanclng procedure) attachment of adequate st!ff -

ness and of the same dynamic characteristics

[centre-of-mass (1.1) Iocatlon, mass and moments of

Inertia] as the rotor (2.1 ), or part of a rotor, it replaces

8.2

mandrel

balancing arbor

rnachlned shaft on which work IS mounted for

balancing (4.1 )

8.3unbalance bias of a mandrelunbalance bias of a balancing arborknown unbalance (3.1 ) added to a balancingarbor (8.2)

NOTE Blaslng a balancing arbor generally serves the~Iu:LPose of either compensating for the residual unbalance

(3 10) that runout of the balanclng arbor’s rotor mountmg

surface causes when this single balancing arbor IS used Inbalancing (4 1) a series of rotors of ’the same mass or ln-

troduang a speclfled unbalance at a speclflc angularposlt}on for the purpose of balanc!ng parts which, after be-

ing r(:moved from the balanclng arbor, are to have a

spw:hcd unbalance.

8.6nodal barrigid bar coupled through bearings to a flexibly sup-

ported rigid rotor (2.2), its motion being essentially

parallel to that of the shaft axis (2.7)

NOTE 1 Its function is to provide correction planeseparation by locating the motion transducers at centres ofrotation corresponding to centres of percussion located incorrection planes (4.8).

NOTE 2 A motion transducer so located has minimumcorrection plane interference ratio (5,26).

8.7calibration rotorrotor (2.1 ) (usually the first of a series) used for thecalibration (5.34) of a balancing machine (5.1)

8.8proving rotortest rotorrigid rotor (2.2) of suitable mass, designed for testingbalancing machines (5.1 ), and balanced sufficientlyto permit the introduction of exact unbalance (3.1) bymeans of additional masses with high reproducibilityof the magnitude and angular position

15

1S/1S0 1925:2001

Annex A(informative)

Illustrated guide to balancingmachine terminology

A.1 General

This annex provides illustrated terminology for bal-

ancing machines. It applies to all forms of

communication, for example technical correspon-

dence, specification and catalogues.

A.2 Figures illustrating terms

The terms m this International Standard are illustratedIn Figures A.1 to A.20.

A.3 Index of equivalent terms

A numerical index of equivalent balancing machineterms In English, French and German is given in thekeys to the figures.

h1S/1S0 1925:2001

12 3 56 78

Key

1 Drive motor

7.. Headstock

3 Protractor/angle scale

4 Index mark

5 Face plate

6 Universal joint drive shaft~ Drive shaft safety guard

8 Drwe adaptor

9 Sub-base

10 Plinth

11 Bed

12 Supporl

Figure A.1 — Machine with end-drive

17

1S/1S0 1925:2001

Key

1

2

3

4

5

6

7

8

9a

9b

10

11

12

Open roller

Roller carriage

Journal diameter scale

Index mark

Height adjustment

Safety bracket (hold-down)

Bearing bridge

Suspension springs

Transducer (pick-up)

Transducer (pick-up), alternative

posihon

support

Riser

Mowng gear (axial adjustment)

6 1

4

3

7

8

gb

Figure A.2 — Support assembly

18

h

1S/1S0 1925:2001

Key

1 Negative load roller

Figure A.3 — Hold-down with negative load bearing

2

Key

1 Centrehne of support

2 Offset

Figure IL4 — Offset roller carriage

19

1S/1S0 1925:2001

1

2

Key

1 Roller

7. Bracket

Figure A.5 — Axial thrust stop

21

Key

1 V-roller carriage

:? Incllned rollers

Figure A.6 — V-roller carriage

Figure A.7 — V-block

1S/1S0 1925:2001

Key

1 Sleeve-bearing carriage

2 Liner

3 Half-sleeve bearing/hydrodynamicor hydrostatic

Figure A.8 — Half-sleeve-bearing carriage

1 \ Q—-z

Key

1 Saddle

2 Degree of freedom

3 Vertical axis saddle-bearmg carriage

Figure A.9 — Saddle-bearing assembly

21

1S/1S0 1925:2001

Key

1 Tlebar arm

~ Tiebar

Figure A.1O — Tiebar frame

12 31

Key

1 support

2 Rotor

3 Spindle

Figure A.11 — Support with spindle heads

22

Key

1 Rc>tor

2 Rotor enclosure

Figure A.12 — Rotor enclosure

4

Key

1 Drwe motor

2 Dr!ving belt

3 Rotor

4 Scanning head (typical formachines with otherthan end-drwe)

Ii

1S/1S0 1925:2001

Figure A.13 — Tangential belt-drive

23

1S/1S0 1925:2001

Key

1 Drive motor

2 Driving belt

3 Rotor

Figure A.14 — Underslung belt-drive

3——e—7c— ,

n

4

‘Y7--Kuw

Key

1 Dfwe motor

2 Driwng belt

3 Rotor

Figure A.15 — Scissor-type belt-drive

24

Key

1 Drive motor

2 Driving belt

3 Rotor

Figure A.17 — Overslung belt-drive

r1S/1S0 1925:2001

3

2

1

Key

1 Drive motor

2 Friction roll

3 Rotor

Figure A.16 — Friction roller-drive

25

1S/1S0 1925:2001

2/

1

Key

1 Open stator

7‘. Rotor

3 Power Input

Figure A.18 — Induction drive

.

Key

1 Ar-jet

;> Rotor

Figure A.19 — Air-drive

26

1S/1S0 1925:2001

1

2

Key

1 Assembly with self-drive

2 Power Input

Figure A.20 — Self-drive

27

1S/1S0 1925:2001

Bibliography

[1] ISO 1940-1:1986, Mechanical vibration —Balance quality requirements of rigid rotors —Part 1: Determination of permissible residualunbalance.

[2] ISO 2041:1990, Vibration and shock — Vo-cabulary.

28

1S/1S0 1925: ZOOI

Alphabetical index

A

above-resonance balancingmachine 5.8

acceptability limit 4.12amount indicator 5.13amount of unbalance 3.3angle indicator 5.17angle of unbalance 3.4angle reference generator 5.19angle reference marks 5.20audit run 5.41axes of inertia 1.2axis of rotation 1.4

B

balance axis 1.2balance quality grade 3.16balance tolerance 4.13balancing 4.1balancing arbor 8.2balancing bearings 5.51balancing machine 5.1balancing machine accuracy 5.24balancing machine minimum

response 5.23balancing machine

sensitivity 5.29balancing plane 4.8balancing run 5.42balancing speed 2.16bearing support 2.13below-resonance balancing

machine 5.6bias mass 8.4bob weight 5.48

c

calibration 5.34calibration mass 4.18calibration rotor 8.7central principal axes 1.2central principal moments of

inertia 1.2centre of mass 1.1centrifugal balancing

machine 5.3check run 5.41claimed minimum achievable

residual unbalance 5.40compensating balancing

machine 5.9compensator 5.16component correction 4.6component mesuring device 5.22controlled initial unbalance 3.17correction mass 4.17

correction plane 4.8correction plane interference 5.25correction plane interference

ratios 5.26counterweight 5.15couple unbalance 3.8couple unbalance interference

ratio 5.27critical speed 1.3cross-effect 5.25cycle rate 5.44

D

design axis 7.4differential test masses 4.21differential unbalance 4.22direct-reading balancing

machine 5.10double compensator 5.5o

dummy rotor 8.1dynamic balancing 4.3dynamic balancing machine 5.5dynamic unbalance 3.9

E

electrical runout 2.19equivalent dh modal

unbalance 6.7

F

field balancing 4.14field balancing equipment 5.12final unbalance 3.10fitment 2.21flexible rotor 2.3flexural critical speed (rotor) 6.1flexural principal mode (rotor) 6.3floor-to-floor time 5.43floor-to-floor time gross 5.43force-measuring balancing

machine 5.6foundation 2.14

I

inboard rotor 2.8index balancing 4.23indexing 4.15indexing unbalance 4.4initial unbalance 3.1 Iisotropic bearing support 2.22

J

journal 2.4journal axis 2.5journal centre 2.6

L

local mass eccentricity 2.12local sensitivity 6.15low-speed balancing 6.11

M

mandrel 8.2mass axis 1.2mass centring 4.16mass eccentricity 2.11master rotor 8.5measuring plane 4.9measuring run 5.41mechanical adjustment 5.36method of correction 4.5minimum achievable residual

specific unbalance 5.39minimum achievable residual

unbalance 5.38modal amplification factor 6.18modal balancing 6.5modal balance tolerance 6.8modal damping ratio 6.21modal eccentricity 6.22modal mass 6.17modal sensitivity 6.19mode function 6.16multilane balancing 6.4multiple-frequency vibration 6.9

GN

gravitational balancingmachine 5.2

H

half-key 2.24hard-bearing balancing

machine 5.6high-speed balancing 6.12

nth modal unbalance 6.6nodal bar 8.6nodal network 5.30non-dimensional speed 6.20non-rotational balancing

machine 5.2null-force balancing machine 5.9

8

29

1S/1S0 1925:2001

0

outboard rotor 2.9

P

parasitic mass 5,31perfectly balanced rotorpermanent calibrationpermissible residual

unbalance 4.13phantom unbalance

indication 5.49pilot 2.23plane separation 5,28

2.105.32

plane separation network 5.30plane transposition 4.26polar correction 4.7practical correction unit 5.14principal axis location 7.3principal inertia axes 1.2

principal moments of inertia

production rate 5.45production rate net 5.45progressive balancing 4.25proving rotor 8.8

Q

quarter points 4,28quasi rigid-rotor 2.15quasi-static unbalance 3.7

R

rabbet 2.23reference plane 4.10

residual unbalance 3.10resonance balancing machineresonant speed 1.3resultant moment (couple)

unbalance 3.13resultant unbalance 3.12rigid free-body 7.1rigid free-body balancing 7.6rigid free-body couple

unbalance 7.5rigid free-body dynamic

unbalance 7.5rigid free-body static

unbalance 7.5rigid free-body unbalance 7.5rigid rotor 2.2rigid-rotor-mode critical speedrotatinq rigid free-bodv 7.2

5.7

6.2

rotational balancing m-achine 5.3rotor 2.1

rotor flexural critical speedrotor flexural principal mode

6.1

6.31.2

s

self-balancing device 5.37sensitivity switch 5.18sensitivity to unbalance 6.14service speed 2.17setting 5.35shaft axis 2.7shaft rotor axis 2.7single-plane balancing 4.2single-plane balancing

machine 5.4slave bearings 5.51slow-speed runout 2.18soft-bearing balancing

machine 5.8

specific unbalance 3.15spigot 2.23static balancing 4.2static balancing machine 5.4static unbalance 3.6susceptibility to unbalance 6.13swing diameter 5.11

T

test mass 4.20test plane 4.11test rotor 8,8thermallv induced unbalance 6.10total ind(cated runouttraverse test 5,46trial mass 4,19trim balancing 4.27two-plane balancing

2.20

4.3two-plane balancing machine 5.5

u

unbalance 3.1unbalance bias of a mandrel

(balancing arbor) 8.3unbalance couple 3.14unbalance mass 3.2unbalance reduction ratio 5.33unbalance vector 3.5

v

vector measuring device 5.21vertical axis freedom 5.47vibration transducer plane 4.24

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