ISO 21250-1:2020
(Main)Rolling bearings — Noise testing of rolling bearing greases — Part 1: Basic principles, testing assembly and test machine
Rolling bearings — Noise testing of rolling bearing greases — Part 1: Basic principles, testing assembly and test machine
This document specifies: — basic principles, testing assembly and the test machine for noise testing of rolling bearing greases; — symbols used in the test methods BQ+, MQ and NQ. This document is applicable for testing rolling bearing greases, especially of unused grease. NOTE Suitable greases are greases of NLGI classes 1 to 3 according to DIN 51818[6]. Suitable greases for lubrication of rolling bearings are especially greases according to ISO 12924. The test method according to this document delivers meaningful results for rolling bearings; however, it can also be applied for greases in similar applications[12][13].
Roulement — Essais de bruit de graisse pour roulement — Partie 1: Règles de base, arrangement d'essais, machine de test
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INTERNATIONAL ISO
STANDARD 21250-1
First edition
2020-07
Rolling bearings — Noise testing of
rolling bearing greases —
Part 1:
Basic principles, testing assembly and
test machine
Roulement — Essais de bruit de graisse pour roulement —
Partie 1: Règles de base, arrangement d'essais, machine de test
Reference number
ISO 21250-1:2020(E)
©
ISO 2020
---------------------- Page: 1 ----------------------
ISO 21250-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 21250-1:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, abbreviated terms and subscripts . 2
5 Basics . 3
6 Grease noise evaluation method . 4
6.1 General and overview . 4
6.2 Calculation method for the grease damping . 4
6.3 Calculation method for peak analysis . 5
6.4 Calculation for SUN analysis . 7
7 Noise testing of greases . 7
7.1 General information . 7
7.2 Measuring principle . 8
7.3 Test machine . 8
7.4 Test setup . 8
7.5 Test bearings and amount of grease . 8
7.6 Test load . 9
7.7 Spindle speed . 9
7.8 Signal recording . 9
7.9 Display .10
8 Calibration .10
8.1 General .10
8.2 Calibration levels .11
8.3 Calibration means .11
9 Error estimation .11
Bibliography .13
© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 21250-1:2020(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 4, Rolling bearings.
A list of all parts in the ISO 21250 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 21250-1:2020(E)
Introduction
The rolling bearing life theory emphasizes the use of pure and homogeneous lubricants as essential for
a long bearing service life. The lubrication of rolling bearings is described in several national standards.
[11]
The GfT worksheet 3 contains theoretical and practical knowledge of rolling bearing lubrication.
Grease lubrication is the most common type of rolling bearing lubrication. The purity grade of bearing
grease is influenced by thickeners, base oils, additives and solid lubricant additives as well as the
manufacturing process and is reflected in the running noise. Therefore, noise testing of rolling bearing
greases is recommended.
In addition, grease noise testing in accordance with this document allows the grease manufacturers
to develop low-noise lubricants with better damping properties. This document can also support the
rolling bearing manufacturers and end-users in the selection of low noise grease with better damping
properties.
This document covers basic principles, requirements for the testing assembly and the test machine to
determine and assess the noise characteristics of bearing grease jointly with ISO 21250-2, ISO 21250-3
and ISO 21250-4.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 21250-1:2020(E)
Rolling bearings — Noise testing of rolling bearing
greases —
Part 1:
Basic principles, testing assembly and test machine
1 Scope
This document specifies:
— basic principles, testing assembly and the test machine for noise testing of rolling bearing greases;
— symbols used in the test methods BQ+, MQ and NQ.
This document is applicable for testing rolling bearing greases, especially of unused grease.
[6]
NOTE Suitable greases are greases of NLGI classes 1 to 3 according to DIN 51818 . Suitable greases for
lubrication of rolling bearings are especially greases according to ISO 12924. The test method according to this
document delivers meaningful results for rolling bearings; however, it can also be applied for greases in similar
[12][13]
applications .
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 492, Rolling bearings — Radial bearings — Geometrical product specifications (GPS) and tolerance values
ISO 5593, Rolling bearings — Vocabulary
ISO 5753-1, Rolling bearings — Internal clearance — Part 1: Radial internal clearance for radial bearings
ISO 15242-1:2015, Rolling bearings — Measuring methods for vibration — Part 1: Fundamentals
ISO 21250-2, Rolling bearings — Noise test of rolling bearing greases — Part 2: Test and evaluation
method BQ+
ISO 21250-3, Rolling bearings — Noise test of rolling bearing greases — Part 3: Test and evaluation
method MQ
ISO 21250-4, Rolling bearings — Noise test of rolling bearing greases — Part 4: Test and evaluation
method NQ
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5593, ISO 15242-1 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2020 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 21250-1:2020(E)
3.1
noise
vibration that is a random mechanical energy process of spectral density varying continuously with
frequency and perceived as acoustic actions that are neither acoustic shocks nor a series of harmonic
tones nor complex tones and which are substantially uniform over time
Note 1 to entry: Noise can be represented mathematically, that is as Fourier integral which can be expressed as
the sum of a series of plain vibrations. Its distinguishing characteristic, as opposed to other acoustic actions with
discrete frequencies, is a spectrum with irregular amplitudes of each frequency.
3.2
start-up noise
v
SUN
noise (3.1) at the start of the bearing testing
3.3
noise level
v
NL
noise (3.1) of the bearing calculated as the average value or rms of measuring points
Note 1 to entry: The number of measuring points and measuring time depend on the test method.
3.4
noise peak
v
NP
peak value of the bearing noise (3.1)
3.5
peak count
number of peak signals exceeding a defined threshold level
3.6
calibrator
measurement standard that provides a sinusoidal vibration speed at certain frequencies and defined
amplitudes
3.7
grease damping
GD
attenuating effect of the lubricant, which is related to the vibration excitation of the bearing
4 Symbols, abbreviated terms and subscripts
The symbols and abbreviated terms contained in Table 1 and the subscripts contained in Table 2 apply
to the noise testing of greases according to test methods BQ+, MQ and NQ.
Table 1 — Symbols and abbreviated terms
Symbol Unit Description
a
BQ+ — Method BQ+ according to ISO 21250-2
GD — Grease damping
a
H — High band, H-band (1 800 Hz to 10 000 Hz)
a
i — Consecutive number
a,b
L — Low band, L-band (50 Hz to 300 Hz)
a
Can be used as subscript, too, where necessary.
b
The L-band is used in noise and vibration analysis in the ISO 15242 series. However, this document does not consider
this frequency range for grease noise testing and its analysis.
2 © ISO 2020 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 21250-1:2020(E)
Table 1 (continued)
Symbol Unit Description
a
M — Medium band, M-band (300 Hz to 1 800 Hz)
a
MQ — Method MQ according to ISO 21250-3
a
M&H — Medium band and high band, M&H band (300 Hz to 10 000 Hz)
n — Number of noise counts
a
NQ — Method NQ according to ISO 21250-4
−1
v µm∙s Vibration velocity
−1
µm∙s Vibration velocity, twice smoothed to the counting point i
v
i
a
Can be used as subscript, too, where necessary.
b
The L-band is used in noise and vibration analysis in the ISO 15242 series. However, this document does not consider
this frequency range for grease noise testing and its analysis.
Table 2 — Subscripts
Subscript-symbol Description
a
grease Greased bearing
b
NL Noise level, average value (of vibration velocity)
normal Acceptable level of normal noise, greased bearing
b
NP Noise peak
pk Peak value
ref Reference, ungreased bearing
Root mean square value of sinusoidal signal which has the same amplitude
rms
with actual peak value range of raceway noise
0–32 Starting interval 0 s to 32 s
32–64 Operating interval 32 s to 64 s
b
SUN Start-up noise of the greased bearing
a
This subscript usually is not written (default).
b -1
In the MQ method, noise values with this subscript can be expressed in µm∙s or in % based on the reference value of
−1
16,9 µm∙s .
5 Basics
In the case of grease lubrication, many factors can affect the degree of cleanliness during operation. For
the initial lubrication and relubrication, clean grease is always requ
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 21250-1
ISO/TC 4
Rolling bearings — Noise testing of
Secretariat: SIS
rolling bearing greases —
Voting begins on:
2020-04-06
Part 1:
Voting terminates on:
Basic principles, testing assembly and
2020-06-01
test machine
Roulement — Essais de bruit de graisse pour roulement —
Partie 1: Règles de base, arrangement d'essais, machine de test
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 21250-1:2020(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2020
---------------------- Page: 1 ----------------------
ISO/FDIS 21250-1:2020(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 21250-1:2020(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, abbreviated terms and subscripts . 2
5 Basics . 3
6 Grease noise evaluation method . 4
6.1 General and overview . 4
6.2 Calculation method for the grease damping . 4
6.3 Calculation method for peak analysis . 5
6.4 Calculation for SUN analysis . 7
7 Noise testing of greases . 7
7.1 General information . 7
7.2 Measuring principle . 8
7.3 Test machine . 8
7.4 Test setup . 8
7.5 Test bearings and amount of grease . 8
7.6 Test load . 9
7.7 Spindle speed . 9
7.8 Signal recording . 9
7.9 Display .10
8 Calibration .10
8.1 General .10
8.2 Calibration levels .11
8.3 Calibration means .11
9 Error estimation .11
Bibliography .13
© ISO 2020 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 21250-1:2020(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 4, Rolling bearings.
A list of all parts in the ISO 21250 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 21250-1:2020(E)
Introduction
The rolling bearing life theory emphasizes the use of pure and homogeneous lubricants as essential for
a long bearing service life. The lubrication of rolling bearings is described in several national standards.
[11]
The GfT worksheet 3 contains theoretical and practical knowledge of rolling bearing lubrication.
Grease lubrication is the most common type of rolling bearing lubrication. The purity grade of bearing
grease is influenced by thickeners, base oils, additives and solid lubricant additives as well as the
manufacturing process and is reflected in the running noise. Therefore, noise testing of rolling bearing
greases is recommended.
In addition, grease noise testing in accordance with this document allows the grease manufacturers
to develop low-noise lubricants with better damping properties. This document can also support the
rolling bearing manufacturers and end-users in the selection of low noise grease with better damping
properties.
This document covers basic principles, requirements for the testing assembly and the test machine to
determine and assess the noise characteristics of bearing grease jointly with ISO 21250-2, ISO 21250-3
and ISO 21250-4.
© ISO 2020 – All rights reserved v
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 21250-1:2020(E)
Rolling bearings — Noise testing of rolling bearing
greases —
Part 1:
Basic principles, testing assembly and test machine
1 Scope
This document specifies:
— basic principles, testing assembly and the test machine for noise testing of rolling bearing greases;
— symbols used in the test methods BQ+, MQ and NQ.
This document is applicable for testing rolling bearing greases, especially of unused grease.
[6]
NOTE Suitable greases are greases of NLGI classes 1 to 3 according to DIN 51818 . Suitable greases for
lubrication of rolling bearings are especially greases according to ISO 12924. The test method according to this
document delivers meaningful results for rolling bearings; however, it can also be applied for greases in similar
[12][13]
applications .
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 492, Rolling bearings — Radial bearings — Geometrical product specifications (GPS) and tolerance values
ISO 5593, Rolling bearings — Vocabulary
ISO 5753-1, Rolling bearings — Internal clearance — Part 1: Radial internal clearance for radial bearings
ISO 15242-1:2015, Rolling bearings — Measuring methods for vibration — Part 1: Fundamentals
ISO 21250-2, Rolling bearings — Noise test of rolling bearing greases — Part 2: Test and evaluation
method BQ+
ISO 21250-3, Rolling bearings — Noise test of rolling bearing grease — Part 3: Test and evaluation
method MQ
ISO 21250-4, Rolling bearings — Noise test of rolling bearing grease — Part 4: Test and evaluation
method NQ
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5593, ISO 15242-1 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
© ISO 2020 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/FDIS 21250-1:2020(E)
3.1
noise
vibration that is a random mechanical energy process of spectral density varying continuously with
frequency and perceived as acoustic actions that are neither acoustic shocks nor a series of harmonic
tones nor complex tones and which are substantially uniform over time
Note 1 to entry: Noise can be represented mathematically, that is as Fourier integral which can be expressed as
the sum of a series of plain vibrations. Its distinguishing characteristic, as opposed to other acoustic actions with
discrete frequencies, is the spectral completeness at irregular amplitude diversity.
3.2
start-up noise
v
SUN
noise (3.1) at the start of the bearing testing
3.3
noise level
v
NL
noise (3.1) of the bearing calculated as the average value or rms of measuring points
Note 1 to entry: The number of measuring points and measuring time depend on the test method.
3.4
noise peak
v
NP
peak value of the bearing noise (3.1)
3.5
peak count
number of peak signals exceeding a defined threshold level
3.6
calibrator
measurement standard that provides a sinusoidal vibration speed at certain frequencies and defined
amplitudes
3.7
grease damping
GD
attenuating effect of the lubricant, which is related to the vibration excitation of the bearing
4 Symbols, abbreviated terms and subscripts
The symbols and abbreviated terms contained in Table 1 and the subscripts contained in Table 2 apply
to the noise testing of greases according to test methods BQ+, MQ and NQ.
Table 1 — Symbols and abbreviated terms
Symbol Unit Description
a
BQ+ — Method BQ+ according to ISO 21250-2
GD — Grease damping
a
H — High band, H-band (1 800 Hz to 10 000 Hz)
a
i — Consecutive number
a,b
L — Low band, L-band (50 Hz to 300 Hz)
a
Can be used as subscript, too, where necessary.
b
The L-band is used in noise and vibration analysis in the ISO 15242 series. However, this document does not consider
this frequency range for grease noise testing and its analysis.
2 © ISO 2020 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/FDIS 21250-1:2020(E)
Table 1 (continued)
Symbol Unit Description
a
M — Medium band, M-band (300 Hz to 1 800 Hz)
a
MQ — Method MQ according to ISO 21250-3
a
M&H — Medium band and high band, M&H band (300 Hz to 10 000 Hz)
n — Number of noise counts
a
NQ — Method NQ according to ISO 21250-4
−1
v µm∙s Vibration velocity
−1
µm∙s Vibration velocity, twice smoothed to the counting point i
v
i
a
Can be used as subscript, too, where necessary.
b
The L-band is used in noise and vibration analysis in the ISO 15242 series. However, this document does not consider
this frequency range for grease noise testing and its analysis.
Table 2 — Subscripts
Subscript-symbol Description
a
grease Greased bearing
b
NL Noise level, average value (of vibration velocity)
normal Acceptable level of normal noise, greased bearing
b
NP Noise peak
pk Peak value
ref Reference, ungreased bearing
Root mean square value of sinusoidal signal which has the same amplitude
rms
with actual peak value range of raceway noise
0–32 Starting interval 0 s to 32 s
32–64 Oper
...
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