GB/T 9239.1-2026Mechanical vibration—Rotor balancing—Part 1:Introduction (English PDF)
机械振动 转子平衡 第1部分:引言
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Issued by
SAMR; SAC
Level / Type
National · Recommended
Issue date
January 1, 1970
Implementation date
January 1, 1970
Scope
GB/T 9239.1-2026 is the English-translated version of 机械振动 转子平衡 第1部分:引言.
GB/T 9239.1-2026 — This Part of GB/T 9239 gives specifications for rotors in a constant (rigid) state. It specifies: a) balance tolerances, b) the necessary number of correction planes, and c) methods for verifying the residual unbalance.
Recommendations are also given concerning the balance quality requirements for rotors in a constant (rigid) state, according to their machinery type and maximum service speed.
These recommendations are based on worldwide experience. This Part of GB/T 9239 is also intended to facilitate the relationship between the manufacturer and user of rotating machines, by stating acceptance criteria for the verification of residual unbalances.
Detailed consideration of errors associated with balancing and verification of residual unbalance are given in GB/T 9239.2. This Part of GB/T 9239 does not cover rotors in a flexible state.
The balance quality requirements for rotors in a flexible state are covered by GB/T 6557.
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Document preview — GB/T 9239.1-2026
National Standard of the People's Republic of China
- ICS
- 21.120.40
Contents
- Foreword3
- Introduction5
- 1 Scope6
- 2 Normative references6
- 3 Terms and definitions7
- 4 Pertinent aspects of balancing11
- 5 Similarity considerations15
- 6 Specification of balance tolerances20
- 7 Allocation of permissible residual unbalance to tolerance planes22
- 8 Allocation of balance tolerances to correction planes24
- 9 Assembled rotors26
- 10 Verification of residual unbalance27
- Annex A30
- Annex B34
- Annex C36
- Annex D37
- Annex E39
- Bibliography42
Foreword
GB/T 9239 "Mechanical vibration - Balance quality requirements for rotors in a constant (rigid) state" consists of the following two parts:
— Part 1: Specification and verification of balance tolerances;
— Part 2: Balance errors.
This Part is Part 1 of GB/T 9239.
This Part is identical to ISO 1940-1:2003 "Mechanical vibration - Balance quality requirements for rotors in a constant (rigid) state - Part 1: Specification and verification of balance tolerances" (English version, Second edition).
This Part is drafted in accordance with ISO 1940-1:2003 and its technical corrigendum 1 published in 2005 by using translation method. The text structure and technical content are consistent with that of ISO 1940-1:2003.
For convenience of use, this Part has made the following editorial modifications:
— DELETE the foreword of ISO 1940-1:2003;
— REPLACE the decimal point symbol "," with the decimal point symbol ".";
— MODIFY the introductory phrase in Clause 2 "Normative references";
— The international standards referenced in Clause 2 of ISO 1904-1:2003 are changed into the corresponding national standards directly referenced by this Part;
— CORRECT the misprints (see the footnote of A.3).
This Part replaces GB/T 9239-1988 "Balance quality of rigid rotors - Determination of permissible residual unbalance".
This Part has made the following modifications to GB/T 9239-1988:
— MODIFY the standard name;
— ADD table of contents, foreword, introduction, and normative references;
— ADJUST the overall structure of the standard according to ISO 1940-1:2003;
— REDEFINE parts of terms;
— INTRODUCE reference planes for balance tolerances; tolerance planes replace the using correction planes;
— DELETE some examples;
— MODIFY the Annex A;
— MODIFY the Annex B;
— ADD Annex C, Annex D, and Annex E;
— ADD the bibliography.
Annex A, Annex B, Annex C, Annex D, and Annex E of this Part are informative.
This Part was proposed by China Machinery Industry Federation.
This Part shall be under the jurisdiction of National Standardization Technical Committee of Mechanical Vibration and Impact.
Responsible drafting organization of this Part: Changchun Institute of Test Machine.
Participating drafting organizations of this Part: Xiaogan Songlin International Measuring Device Co., Ltd., Changchun Zhonglian Test Equipment Co., Ltd., Shanghai Schenck Machinery Co., Ltd., No. 6354 Institute of China State Shipbuilding Corporation, and Zhengzhou Machinery Research Institute.
Main drafters of this Part: Liu Zhili, Zhang Shimin, Shao Chunping, Wang Chaorong, Yang Dechun, and Huang Runhua.
The historical version replaced by this Part is as follows:
— GB/T 9239-1988.
Mechanical vibration - Balance quality requirements for rotors in a constant (rigid) state - Part 1:
Specification and verification of balance tolerances
1 Scope
This Part of GB/T 9239 gives specifications for rotors in a constant (rigid) state. It specifies:
a) balance tolerances,
b) the necessary number of correction planes, and
c) methods for verifying the residual unbalance.
Recommendations are also given concerning the balance quality requirements for rotors in a constant (rigid) state, according to their machinery type and maximum service speed. These recommendations are based on worldwide experience.
This Part of GB/T 9239 is also intended to facilitate the relationship between the manufacturer and user of rotating machines, by stating acceptance criteria for the verification of residual unbalances.
Detailed consideration of errors associated with balancing and verification of residual unbalance are given in GB/T 9239.2.
This Part of GB/T 9239 does not cover rotors in a flexible state. The balance quality requirements for rotors in a flexible state are covered by GB/T 6557.
2 Normative references
The provisions in following documents become the provisions of this Part through reference in this Part of GB/T 9239. For dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this Part, however, parties who reach an agreement based on this Part are encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies.
9 Assembled rotors
9.1 General
Assembled rotors may be balanced as integral rotors or on the component level. For each assembly, the unbalances of the components superimpose and assembly errors create additional unbalances, for instance, because of runout and play (see GB/T 9239.2 for details).
NOTE: If assembly errors are not decisive, the choice of balancing process may be governed by the availability of balancing machines.
9.2 Balanced as a unit
The best way to take care of all unbalances in the rotor and all related assembly errors in one step is to balance the rotor as a fully assembled unit.
If a rotor is balanced as an assembly but needs to be disassembled afterwards (e.g.
for mounting into the housing), it is recommended to mark each component angularly to ensure identical angular positions during reassembly.
NOTE: The above-mentioned problems with runout and play can still exist.
9.3 Balanced on component level
If individual components are balanced separately, the following comments are important.
a) Usually all components are balanced to the same specific residual unbalance (see Clause 5). However, allowing for additional assembly errors (see GB/T 9239.2) means that the specific residual unbalance of each component shall be smaller than the specific residual unbalance for the assembly.
b) If this causes problems (e.g. with a light fan or pulley on a heavy armature) any distribution rule is allowed, provided that the total unbalance of the assembly is kept within tolerance.
c) Prior agreement between the manufacturer and user should be reached as to the attachment of connecting elements such as keys (see GB/T 16808).
If the balance tolerance for an assembly cannot be achieved by balancing each component separately, the assembly shall be balanced finally as a unit. In such cases, it is recommended to reconsider whether balancing on the component level is really necessary or if it may be omitted.
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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 42 pages — is available in the English PDF.
Referenced standards
Normative references
GB/T 9239
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Related Standards
GB/T 9239.1-2006 — Mechanical vibration -- Balance quality requirements for rotors in a constant (rigid) state -- Part 1: Specification and verification of balance tolerances
GB/T 9239.11-2025 — Mechanical vibration - Rotor balancing - Part 11: Procedures and tolerances for rotors with rigid behaviour
GB/T 9239.12-2021 — Mechanical vibration - Rotor balancing - Part 12: Procedures and tolerances for rotors with flexible behaviour
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