This standard specifies guidelines for the development of test evaluation and use of statistical evaluation methods for the reliability of electromechanical products. This standard is applicable to the reliability evaluation of mechanical, electrical, instrumentation and other products. It can also guide enterprises to improve product reliability and serve as a reference for relevant departments to carry out technical supervision, random inspection and certification of product reliability. JB/T 7518-1994 Guidelines for Reliability Evaluation of Electromechanical Products JB/T7518-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T7518-94
Guidelines for Reliability Assessment of Electromechanical Products
Published on October 25, 1994
Ministry of Machinery Industry of the People's Republic of China
Implementation on October 1, 1995
Mechanical Industry Standard of the People's Republic of China
Guidelines for Reliability Assessment of Electromechanical Products
1 Subject Content and Applicable Models
JB/T7518-94
This standard specifies guidelines for the development of test assessments of the reliability of electromechanical products and the use of statistical assessment methods. This standard is applicable to the reliability assessment of mechanical, electrical, instrumentation and other products, and can also guide enterprises to improve product reliability and serve as a reference for relevant departments to carry out technical supervision, random inspections and certification of product reliability. 2 Terms and Definitions
2.1 Failure
An event in which a product ceases to be able to complete its specified functions. 2.2 Fault
The state in which a product cannot perform its specified functions. This does not apply to preventive maintenance or other planned activities or to the lack of external resources. Faults are usually the state after the product itself fails, but they may also exist before failure. 2.3 Relevant Fault
Faults that must be taken into account when interpreting test or work results or calculating reliability values. 2.4 Secondary Fault
Failure of a product caused directly or indirectly by the failure or fault of another product. 2.5 Critical Fault
Failure that may cause personal injury, damage to important objects or other intolerable consequences. 2.6 Serious Fault
Failure that affects the main functions due to damage to major components. Common Fault
Failure that affects the functions due to damage to components and can be eliminated in a short time by using random work. 2.8 Slight Fault
Failure that affects the functions due to damage to components and can be eliminated within the preventive maintenance time. 3 Purpose and principles of assessment
Purpose of reliability assessment
To find out the weak links in the reliability of existing products or trial-produced prototypes, improve them, and promote the growth of reliability; to identify the advantages and disadvantages of products, conduct comparative analysis, and determine the improvement goals; to estimate and analyze the reliability level of existing products, and accumulate basic data for the reliability design of new products. 3.2 Principles of assessment methods
It should be able to fully expose the main failure modes:
It should be comparable with the reliability of similar products; it should be able to assess the reliability of products:
It should be easy to implement, economical and reasonable.
Approved by the Ministry of Machinery Industry on October 25, 1994
Implemented on October 1, 1995
The assessment method should be selected by comprehensively weighing the above principles. 4 Reliability Indicators
4.1 Selection of Reliability Indicators
JB/T7518-94
Reliability indicators of electromechanical products should generally be in accordance with Appendix A (Supplement). 4.1.1 For products that require the control of the number of failures, indicators such as failure rate, mean time between failures (MTBF), and reliability are selected; for products that require durability, indicators such as reliable life and service life are selected. 4.1.2 For complete equipment and systems that emphasize availability, single or multiple indicators such as availability, mean time between failures, accuracy retention, mean time to repair (MTTR), average repair rate, and warranty cost rate are selected. 4.1.3 In order to monitor and control early failures of products, mean time before first failure (MTTFF) or average failure rate during early failure period are selected as evaluation indicators.
4.1.4 Failure classification counts or weighted counts can be used when counting failures. The indicators that use fault classification counting or fault classification weighted counting should be explained. For example, the MTBF that only counts the number of downtime failures is called downtime failure MTBF, and the MTBF that only counts the number of warranty failures or serious failures is called warranty failure MTBF or serious failure MTBF. When the number of failures is counted by option, the weighting coefficient should be scientific and reasonable.
4.2 Determination of indicator values
It should be based on user surveys and data accumulation, and weighed according to the following factors: a. User needs:
The level of existing products;
The level of competitor products;
d. The feasibility of implementation in terms of technology and economy. 5 Fault classification and criterion
5.1 Definition and criterion of faults
In the product reliability assessment standard, the definition and criterion of faults should be clearly defined. Any state or event that makes the product unable to perform the specified function should be judged as a fault or failure, and should be recorded in detail. 5.2 Failure Correlation
When evaluating product reliability, failures caused by inherent defects of the product itself should be judged as correlated failures and must be included in the interpretation of test results or calculation of reliability values. The criteria for inclusion should be clearly defined; failures caused by improper use, maintenance or other external factors should be judged as non-correlated failures and may not be included in the interpretation of test results or calculation of reliability indicators, but detailed records should be made during the test. 5.3 Dependent Failures
Dependent failures are caused by the failure or failure of another product. When interpreting test results or calculating reliability values, they may not be included. Only the primary failure that caused the dependent failure is counted. However, when weighting the failure classification, the severity of the dependent failure should be considered. 5.4 Repeated Failures
Failures with the same failure mode that occur multiple times should be included each time if they are correlated failures. 5.5 Failure Severity
Failures can be divided into four categories according to their severity: fatal failures, serious failures, general failures, and minor failures. If weighted counting is used, the weighting coefficient should be determined in combination with the product use requirements, fault classification and fault frequency. 6 Distribution Assumptions and Sampling Principles
6.1 Failure Interval Time Distribution Assumptions
For products for which there is no sufficient data to verify and determine the failure interval time distribution, the following assumptions are adopted; a.
For complete equipment composed of a large number of parts and having multiple failure modes, complex components and complete products mainly composed of electronic components, the exponential distribution assumption can be adopted. For machine parts composed of a small number of parts and mainly with one or a few failure modes, the Chibull distribution assumption can be adopted. b.
c. If there is sufficient data, it can be determined after verification. 6.2 Sampling Principles
a. When using random sampling, the parent population must be essentially the same. b. The sampling plan should be determined based on the scale of the product production batch and the cost of the prototype available for testing, generally about 10% of the batch production. It can also refer to relevant standards or be self-determined. c. The sampling method can be single sampling, sequential sampling or other methods. 7 Test
7.1 Test method
7.1.1 Product reliability assessment can be carried out by various methods such as laboratory testing, field testing and user usage data assessment. 7.1.2 For the assessment purpose of mastering the product reliability level and improving it, the measurement test plan can be adopted. The tail test method, the number of test products, the load test time or the number of intercepted failures should be specified. 7.1.3 For the assessment purpose of reliability supervision or contract acceptance, the verification test plan can be adopted. The sampling method, sampling risk rate, the number of test products, the cumulative test time or the cumulative failure effect of qualified judgment should be specified. 7.2 Test conditions
7.2.1 The test conditions should be clearly specified, including the name of the test equipment, model specifications, test site, test load and speed frequency parameters, loading procedures, environment and power supply components, as well as the micro-fault detection cycle and method. 7.2.2 The test conditions should simulate the actual use conditions and environmental conditions, and fully expose the possible failure modes. 7.2.3 If the accelerated test method is used, the following conditions should be met: a.
The acceleration method used should have obvious accelerability: b.
It should neither change the failure mode nor the original failure mechanism: e.
The acceleration coefficient is known.
8 Test products and maintenance requirements
8.1 Before the test, the test product should meet the following conditions: a. It has qualified performance and functions:
b. It is a batch product produced under normal production conditions or a newly developed product. 8.2 Preventive maintenance during the assessment process
8.2.1 The preventive maintenance procedures to be implemented during the assessment process should be specified. In principle, the procedures should be consistent with the maintenance procedures performed during actual use.
8.2.2 During the assessment process, preventive maintenance performed according to the prescribed procedures will not be counted as a failure count, and any repair and maintenance that does not comply with the prescribed procedures will be counted as an associated failure count. 9 Collection and assessment of user usage data
User usage data assessment refers to the use of data collected from the user's site to make a reliability assessment of the product. 9.1 Selection of data collection points and observation samples 9.1.1 Use as many data tracking collection points as possible, at least 2 to 3. 9.1.2 The conditions of the collection points must be that the operating conditions and use environment of the product are representative, that is, the workload, work shifts, operation and maintenance procedures, use environment, etc. meet the requirements specified in the design or product manual. 9.1.3 The selected observation sample should be a batch product under the same production conditions and a qualified product with a similar service history. 9.2 Data collection
JB/T7518-94
9.2.1 The user usage data recording form should be designed in advance. The form should be simple and clear, easy to fill in, and can refer to Appendix B (reference). Before data collection, the recorder should be trained or given a job briefing to explain the key points of recording and the recorder's duty to provide reliable data. 9.2.2
9.3 Identification and detection of on-site faults
9.3.1 The fault judgment criteria that can distinguish the inherent reliability and the reliability of use of the product shall be specified. Faults that are caused by use problems shall also be recorded, but they shall not be included in the assessment.
9.3.2 During the assessment process, the replacement of consumable parts and accessories that have reached the specified life span may not be counted as a fault, but records shall be made. 9.3.3 There shall be corresponding fault monitoring means (continuous or periodic) for the corresponding fault judgment criteria. It is best to use intuitive and easy-to-test fault judgment criteria. For example, faults based on shutdown are easy to monitor and record, which can improve the accuracy of data recording. If conditions permit, a timer can be used for timing monitoring to ensure the accuracy of timing. bZxz.net
9.4 Observation period
The evaluation of user usage data should be based on the accumulation of usage data over a long period of time, and the observation period should be at least half a year or one usage period. The data should be recorded from the start of product testing, and early failures and normal usage periods should be tracked. 10 Data processing
As long as the evaluation purpose can be achieved, the simpler the data processing, the better. 10.1 Point estimation
To understand the reliability level of the product and the relative growth of the day, the point estimation analysis method can be used. 10.2 Interval estimation
The confidence value of the evaluation index using interval estimation is generally recommended to be in the range of 60% to 80%. 10.3 Others
Data processing can use other processing methods such as graphical estimation and numerical calculation. Computer analysis and Weibull probability paper analysis are recommended first.
Reliability index system of electromechanical products
General products
Eight complete machine components>
Material or consumable parts
Disposable work products
JB/T7518-94
Appendix A
Reliability index system table of electromechanical products
(supplement)
Reliable life (B10, B20 life median life, etc.) Average life
Durability
Fault-free
Maintainability
Availability| |tt||Economy
Storage life
Service life
Mean overhaul life (or average maintenance cycle)Reliability
Failure rate
Mean time between failures (MIBF)
Mean time before first failure (MTTFF)Average premature failure rate
Maintainability
Mean repair rate
Mean time to repair (MTTR)
Inherent availability [MTBF/（MTBF+MTTR)]Forced downtime rate [MTTR /（MTBF+MTTR）Availability (or availability, start-up rate, technical utilization factor, etc.)
Life cycle cost
Warranty cost rate
Average maintenance cost
Reliability, average life, failure rate
Distribution parameters
Stability of characteristic values ​​(mean, deviation range)Reliability, success rate, hit rate
Unreliability, malfunction rate
User unit (name)
Product name
JB/T7518-94
Appendix B
User usage data record
(reference)
Correspondence address
Specification model
Postal code
Factory date
Original number Fault occurrence time Cumulative working time Fault phenomenon Number of faults Cause of fault Repair time Repair original Parts replaced Name Quantity Condition
Additional remarks:
JB/T7518-94
This standard is proposed and managed by the Reliability Technology Center of the Mechanical Science Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Reliability Technology Center of the Mechanical Science Research Institute of the Ministry of Machinery Industry. Standard drafters Sun Hui, Chu Xianlan, He Dongda, Song Yun, Song Gang,B20 life median life, etc.) average life
Durability
Failure-free
Maintainability
Availability
Economy
Storage life
Service life
Mean overhaul life (or average maintenance cycle)Reliability
Failure rate
Mean time between failures (MIBF)
Mean time before first failure (MTTFF)Average premature failure rate
Maintainability
Mean repair rate
Mean time to repair (MTTR)
Inherent availability [MTBF/(MTBF+MTTR)]Forced downtime rate [MTTR/(MTBF+MTTR)Usage availability (or availability rate, start-up rate, technical utilization factor, etc.)
Life cycle cost
Warranty cost rate
Average Maintenance cost
Reliability, average life, failure rate
Distribution parameters
Stability of characteristic values ​​(mean, deviation range) Reliability, success rate, hit rate
Unreliability, malfunction rate
User unit (name)
Product name
JB/T7518-94
Appendix B
Record sheet of user usage data
(reference)
Correspondence address
Specification model
Postal code
Factory date
Failure sequence number Failure occurrence time Cumulative working time Failure phenomenon Number of faults Cause of failure Repair time Repair reason Name and quantity of parts replaced
Additional notes:
JB/T7518-94
This standard is proposed and managed by the Reliability Technology Center of the Mechanical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Reliability Technology Center of the Mechanical Science Research Institute of the Ministry of Machinery Industry.B20 life median life, etc.) average life
Durability
Failure-free
Maintainability
Availability
Economy
Storage life
Service life
Mean overhaul life (or average maintenance cycle)Reliability
Failure rate
Mean time between failures (MIBF)
Mean time before first failure (MTTFF)Average premature failure rate
Maintainability
Mean repair rate
Mean time to repair (MTTR)
Inherent availability [MTBF/(MTBF+MTTR)]Forced downtime rate [MTTR/(MTBF+MTTR)Usage availability (or availability rate, start-up rate, technical utilization factor, etc.)
Life cycle cost
Warranty cost rate
Average Maintenance cost
Reliability, average life, failure rate
Distribution parameters
Stability of characteristic values ​​(mean, deviation range) Reliability, success rate, hit rate
Unreliability, malfunction rate
User unit (name)
Product name
JB/T7518-94
Appendix B
Record sheet of user usage data
(reference)
Correspondence address
Specification model
Postal code
Factory date
Failure sequence number Failure occurrence time Cumulative working time Failure phenomenon Number of faults Cause of failure Repair time Repair reason Name and quantity of parts replaced
Additional notes:
JB/T7518-94
This standard is proposed and managed by the Reliability Technology Center of the Mechanical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Reliability Technology Center of the Mechanical Science Research Institute of the Ministry of Machinery Industry.
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