Some standard content:
Mechanical Industry Standard of the People's Republic of China
Methods for evaluating casting quality
Subject content and scope of application
JB/T 7528.- 94
This standard specifies the methods for evaluating the quality of various cast metals and alloy castings produced by sand casting, metal mold casting, low-pressure casting, pressure casting and investment casting. This standard is applicable to the evaluation of casting quality. 2 Reference standards
JB/JQ82001 General rules for quality classification of castings
3 General rules
3.1 The basis for evaluation is JB/JQ82001 and relevant standards (i.e. relevant international standards, current national standards, industry standards, foreign advanced standards or enterprise standards or technical indicators specified in relevant technical documents). 3.2 When the technical indicators specified in the enterprise's internal control standards are inconsistent with the technical indicators specified in national standards or industry standards, the higher indicator shall prevail.
3.3 The quality evaluation of castings for major new products or quality dispute arbitration shall be carried out in accordance with the test items and indicators specified in the relevant technical requirements.
3.4 The test items shall be determined according to the items specified in the relevant standards or technical documents of the castings being evaluated. 3.5 In order to ensure the quality of castings, the performance, life, reliability, etc. of the castings shall be directly affected by the following factors: The quality veto power is exercised over the key quality indicators that directly affect or play an important role. The number of key indicators is determined according to the requirements for casting quality. The key indicators and numbers of different types of castings may be different.
3.6 Castings with special requirements can be specially treated. 4
Sampling regulations
4.1 Sampling objects
Finished castings that have been accepted by the quality inspection department of the production unit. 4.2 Sampling method
Random sampling.
4.3 Sampling location
Drawings from the finished casting warehouse of the production unit. 4.4 Sampling quantity
For castings produced in batches and mass production, the sampling number is shown in Table 1. For castings produced in single pieces and small batches, the sampling number is shown in Table 2. Table 1 Sampling number of castings produced in batches and mass production Casting weight range.kg
Sampling number
China Approved by the Ministry of Machinery Industry of the People's Republic of China on October 25, 1994 218
>100～1000
Implemented on October 1, 1995
Casting weight range, kg
Sampling number
4.5Sampling base
Sampling base see Table 3.
JB/T7528--94
Table 2 Single piece and small batch production Sampling number of castings produced 100
Production batch
Batch and mass production
Single piece production
5 Inspection items, conditions and methods
>100～1000
Table 3 Sampling base
Sampling base
5～10 of the sampling number
3--5 times of the sampling number
5.1 Inspection items for casting quality The project includes two parts: the physical quality of castings, technical management and after-sales service. 1000
5.2 The physical quality of castings should be divided into external quality and internal quality. External quality includes surface roughness, dimensional tolerance, weight tolerance, surface defects and cleaning status, and internal quality includes mechanical properties, chemical composition, metallographic structure, internal defects and pressure resistance test. In addition to these items, they can also be added according to relevant technical requirements. 5.3 Technical management mainly includes: process documents and process discipline management, standardization and metrology management, testing capabilities and quality assurance management, etc.: 5.4 After-sales service mainly includes: user evaluation, after-sales service, information feedback and processing, etc. 5.5 Inspection personnel should be full-time quality management personnel, quality inspectors and testers. Inspection tools, instruments and equipment should meet the requirements of metrological verification and quality inspection, and be able to provide accurate and reliable inspection data. 5.6 Each inspection item shall be operated in accordance with relevant standards or technical requirements. 5.7 When the qualified product rate (including graded product rate) of mechanical properties, chemical composition, metallographic structure, pressure test and other items is statistically analyzed, the original voucher of the test report of any two months of random sampling in the past year is used as the basis. 6 Assessment method
6.1 The multi-index weighted comprehensive assessment method is adopted for the assessment of casting quality. The first-level index of casting quality assessment is: physical quality of castings, technical management and after-sales service. The weighted coefficients of the first-level index are shown in Table 4. Table 4
Weighted coefficients
Grade index weighted coefficients
Physical quality of castings
Technical management
After-sales service
6.2 Each test item in the physical quality of castings is a secondary index. The weighted coefficients of each secondary index of the physical quality of castings are shown in Table 5. The letters A, B, C, .. in the table indicate the order of arrangement from important to minor in the test items. When the test items are determined, the weighted coefficients of each test item are selected from Table 5 accordingly.
Number of inspection items
Weighting coefficient of each item
JB/T 7528--94
Weighting coefficient of finished casting inspection items and each secondary indicator6
6.3 The weighting coefficient of the primary indicator of technical management is shown in Table 6.7
The secondary weighting coefficient of technical management
Weighting coefficient
Process document and process discipline management
Standardization and metrology management
W22: 0.25
Inspection capability and quality assurance management
W23 0. 25
The weighting coefficient of the primary indicator of after-sales service is shown in Table 7. Table 7 Weighted coefficients of secondary indicators of after-sales service Month
Weighted coefficient
User evaluation and opinion
After-sales service
Information feedback and processing
5 The implementation of quality veto power for key items in casting quality assessment can be divided into two forms. One is single item veto, that is, in the test data of industry-level indicators, when the rate of unqualified products or its lower grade product rate is greater than or equal to 30% of the actual measured results of the item, regardless of the high comprehensive average score of the single item, the single item will be vetoed as unqualified products or lower grade products. The other is casting quality grade decision, that is, in the key item indicators, the casting is assessed according to the quality grade of the lowest grade item. 6.6 When implementing single item veto, the single item score is not multiplied by the veto power coefficient, and only the lowest score of the veto grade is counted. If unqualified veto is implemented. This single item gets 0 points; when the qualified product is rejected, this item gets 60 points; when the first-class product is rejected, this single item gets 80 points. When the casting quality grade is rejected, the sum of the scores of the indicators that are better than the veto item is multiplied by the veto coefficient, and the scores of the veto items and the scores of the lower veto items are added to get the total score of the casting quality grade. The weighting coefficient of the quality grade veto is shown in Table 8 Table 8 Weighting coefficient of quality grade veto
Grade veto
Weighting coefficient
Superior product
WrSuperior=-1
W.--0.95
Qualified product
Unqualified product
6.7 The evaluation method is to convert the characteristic value representing the quality of the casting into fullness (starting), and comprehensively calculate the satisfaction to evaluate the quality grade: the satisfaction corresponding to the quality grade is shown in Table 9.
Quality grade
Unqualified products
Qualified products
·Qualified products
Superior products
JB/T 7528—94
Satisfaction degree corresponding to quality grade
6.8 The satisfaction degree of the secondary indexes of the physical quality of castings that can be graded is shown in Table 10, and the satisfaction degree of the secondary indexes that are not graded is shown in Table 11. Table 10 Satisfaction degree of the secondary indexes of the physical quality of castings that can be graded Item
Satisfaction degree (E)
Full elongation (E)
Unqualified products
Qualified products
The satisfaction degree of the secondary indexes of the physical quality of castings that are not graded is not
Superior products
6.9 The technical management assessment method adopts the form of deduction, but each item is scored until all the points are deducted, and no negative points are allowed. Inspection contents and scoring methods are shown in Table 12.
Table 12 Evaluation method of technical management
Inspection items
1. Are process drawings, casting drawings, and process cards complete?
2. Technical content of process regulations is comprehensive
There are regulations for changes in process documents, and they are complete
There are process discipline systems and
assessment methods
5. The incoming raw and auxiliary materials shall have inspection reports. 6. Inspection pass rate of mold and core sand. Inspection methods: 1. Spot check casting drawings and process cards. 2. Check the process specifications related to the evaluated products. Scoring method: 1. Incomplete. 4 points will be deducted for missing items. 2. 10 points will be deducted for no process specifications, and 4 points will be deducted for incomplete items. 3.Check the relevant regulations of the change procedures 13. No regulations will be deducted 10 points - no records of regulations and change records 4. Check the relevant regulations, systems and assessment records 5. Check the quality inspection reports and re-inspection reports of raw sand alloy furnace materials, raw iron, coke, and coatings 6. Spot check the routine inspection reports of molds and core sands for two months and deduct 6 points 4. No system will be deducted 10 points, no assessment records will be deducted 10 points, and poor implementation will be deducted 4 points 5. No incoming material report will be deducted 6 points , 4 points will be deducted for no re-inspection report, 2 points will be deducted for incomplete report 6. 85% of mold and core sand qualification rate will be deducted, 4 points will be deducted for failure to comply with regulations Sand mold hardness test record 8. Coating test record 9. Assembly, pattern test, and maintenance record 10. Melting process control and record 11. Cleaning and repair process control and record 12. Whether there are special (part-time) quality inspectors and information between each process 1. There are current national and industry standards and the current standards are implemented 2. There are manufacturing enterprise (internal control) standards or indicators JB/T 7528 --94
Continued Table 12
Inspection method
Spot check on machine modeling for two months
8. Record of viscosity test
9. Inspection and repair of tooling and modeling
10. Whether the batch of added materials is correct, analysis before and after the furnace
, melting records such as furnace unloading and pouring temperature
11. Repair welding and re-inspection records
Evaluation method||t 7. If the hardness pass rate is lower than 90%, 4 points will be deducted. 18. If there is no record, 6 points will be deducted. 9. If there is no record, 6 points will be deducted. 10. If one item is unqualified, 2 points will be deducted. If there is no record, 10 points will be deducted. 11. If there is no re-inspection record, 4 points will be deducted. 12. If there is no process quality inspector, 1 point will be deducted. If there is no process quality inspector, 1 point will be deducted. 12. Quality information transmission and feedback record processing results 1. Check whether there are standards and whether they are implemented. 2. Whether there are enterprise standards. 3. Whether there is standardization and metrology management. 3. Check relevant systems and metrology inspection systems. 4. Whether there are professional (part-time) standardization and metrology institutions or personnel. 15. Complete chemical analysis instruments. 6. Mechanical properties test equipment. 7. Whether the testing instruments and equipment are
regularly calibrated
determine the report
4. Check whether it is implemented, check
timely handle the quality information deduct 4 points
1. Deduct 10 points for no standards. Deduct 2 points for implementing the old standards
and deduct 4 points for poor implementation
2. Deduct
for no enterprise standards or internal control indicators. Deduct
3. Deduct 4 points for no system. Deduct
4 points for poor implementation
for no organization or personnel
5. Whether the chemical analysis instruments can meet
15. Deduct 8 points for incomplete chemical analysis
quality control requirements
6. 4 points will be deducted for missing performance test items. 6. Whether it can meet the production requirements (tensile strength, service strength, elongation, cross-sectional shrinkage, impact, metallographic, flaw detection, pressure, etc.) 7. The main instruments and equipment must have measurement certificates 7. The main instruments and equipment do not have metrological qualification certificates (pieces). 4 points will be deducted. The sand mold hardness and light requirements are not inspected. The paint shop can require [not inspected]. Inspection items: whether the inspectors have been trained and certified. 9. Random inspection of chemical analysis reports. 10. Random inspection of mechanical properties tests. 11. Quality assurance and supervision. 12. Sample storage. JB/T 7528---- 94
Continued Table 12
Inspection method
Physical and chemical, non-destructive testing personnel should have
9. Spot check two months of original records
10. Spot check two months of original records
Evaluation method
8. Test personnel’s ID card will be deducted 4 points
9. Incomplete chemical composition report will be deducted 8 points
10. Incomplete mechanical properties test report will be deducted
11: Spot check the first batch or regularly check the records 11. If there is an archive record, deduct 4 points.
12. Whether the samples for inspection are numbered 12. 4 points will be deducted if the sample is not stored, 4 points will be deducted if the management number is not good, and 4 points will be deducted if the chemical composition is not checked and the receipt is not made. The chemical composition is not described. If there is no requirement, it is not required. 6.10 After-sales service evaluation method adopts the form of deduction until each item is deducted, but no negative points are allowed. The test content and scoring method are shown in Table 13. Table 13 After-sales service evaluation method Inspection items User comments Inspection method 1. Random inspection User comments Regularly visit users and take the initiative to 1. Spot check visit after-sales service record door-to-door visit
Quality information feedback and handling 1. Spot check information feedback system management
2. Whether there are full-time and part-time personnel
3. Spot check information feedback records
4. Whether the information feedback can be handled in time
Quality grade assessment scoring method
Single score of actual castings
Scoring method
1. No points will be deducted if the user is satisfied, 10 points will be deducted if the evaluation is relatively satisfied, and 30 points will be deducted if the evaluation is generally satisfactory. No points will be scored if the user is dissatisfied
1. Regular visits, with records No points will be deducted for recording
2. Regular visits. 10 points will be deducted for no record
3. No points will be deducted for not implementing well
1. No points will be deducted for no system, 10 points will be deducted for incomplete system
2. 10 points will be deducted for no full-time or part-time staff
3. 10 points will be deducted for incomplete information record
4. 10 points will be deducted for untimely information feedback, 15 points will be deducted for no
processing results
Evaluation in recent years
Wu Zhong: Cn
Single score of physical castings:
JB/T 7528.94
Single weighting coefficient of the second-level indicator of physical castings; - number of samples;
Single score of the main part.
7.1.1 Calculation method of graded secondary indicators a.
When the qualified products of dimensional tolerance and weight tolerance are graded as first-class products: 40×(qualified product marked value minus actual measured value) E(,
Qualified product standard value - superior product standard value When the qualified product to superior product is divided into four grades with inch tolerance and weight tolerance, there are two forms of calculation. When the measured value is between qualified product and
first-class product:
20×(qualified product standard value - measured value)Qualified product standard value - first-class product standard value When the measured value is between first-class product and superior product: E=C,
20×(first-class product standard value measured value)First-class product standard valueSuperior product standard value
When E<60 points, E=0 points.
7.1.2 Calculation method of secondary indicators without classification Test data qualified: E100 points;
Test data unqualified: E=0 points.
7.2 Total score of various indicators of castings
CH =-ECI
Where: (…Total score of various indicators of castings; Ch,
Score of the first item of the actual casting.
7.3 Score of the actual quality grade of castings
Cs excellent WF excellent ZCn excellent CH
Cs-- equal-Wr-- equal ZCn excellent + ECu-
Cs qualified-WF qualified (ZCD excellent + ZCD-equal) + ZCD 60
Cs unqualified means = W food (ECD + ECl-equal + EC inclusive) + ECn qualified In the formula: s excellent "-·· is evaluated as a high-quality casting score; equal is evaluated as--equal casting score;
Cs inclusive n
is evaluated as a qualified casting score;
(small one is evaluated as a non-qualified casting score 7.4 Physical quality of castings--total score after weighted grade 2
(8)
JB/T7528-94
Formula: (…--physical quality of castings·total score after weighted grade; physical quality rating score of castings;
physical grade weighting coefficient of castings.
7.5 Technical management---weighted score after grade
D--WE (DW.)
Where: I)·…technical management··total score after weighted grade; W technical management grade weighting coefficient;
D, score of the i-th technical management item;
the secondary weighting coefficient of the i-th technical management item.
7.6 Total weighted score of after-sales service level 1
E-WZ(EWs,)
Wherein: E—- Total weighted score of after-sales service level 1; W after-sales service level weighting coefficient;
E,--- Score of the ith item of after-sales service;
W weighted coefficient of the ith item of after-sales service level 2. 7.7 Comprehensive assessment score of casting product quality
F-Cv+D +-Ev
Wherein: F-
Comprehensive assessment score of casting product quality.
(11)
.JB/T7528--94
Appendix A
Additional points for degree of difficulty
(reference)
Since there are many types of castings, the process difficulty and technical level vary greatly. In order to make the quality assessment of castings with different process methods, different materials and different uses on a fair, consistent and reasonable basis, they are adjusted and processed in the form of additional points for degree of difficulty. See Table A for additional points for degree of difficulty].
Main castings
Special requirements
A Very complex
B Complex
A Difficult
A Very important
B General requirements
A Very high
Additional points for difficulty
The wall is very thin, the wall thickness is uneven, and the hook degree is>1,5. The outer shape and inner cavity are very complex. The number of cores is different. The dimensional accuracy requirements are very high, and the machining requirements are very high. The wall is thin, the wall thickness is uneven, and the hook degree ≥! ：3～1：5. The outer shape and inner cavity are complex, and the number of cores is 3 to 4. The requirements for dimensional accuracy are high, and the requirements for machine shed workers are high. Steel castings and ultra-low carbon steel have strict requirements on the composition of slag. Iron castings have strict requirements on carbon equivalent and metallographic structure. Non-ferrous castings have strict control over the composition. Steel castings and low-carbon steel have strict control over the composition and slag. Iron castings have requirements on carbon equivalent and metallographic structure. Non-ferrous castings have strict control over the composition. They are key castings on the host, which are crucial to the performance, life and safety of the host. They are important castings on the host, which are crucial to the performance, life and safety of the host. They have high requirements for pressure resistance, heat resistance, wear resistance or corrosion resistance, and strict requirements for internal radiographic flaw detection. They have high requirements for pressure resistance, heat resistance, wear resistance or corrosion resistance, and strict requirements for internal radiographic flaw detection. When it contains additional points, the actual scoring method for castings is: Gv=(Gs+A)W)
Wu Zhong: A--bzxz.net
Additional points total score
Appendix B
Record form and casting quality assessment example
(reference part)
Additional points
B1 The summary of casting product quality inspection data and the list of assessment results are shown in Table B1, the casting appearance quality inspection record table is shown in Table B2-Table B5, and the casting internal quality inspection record table is shown in Table B7. 22
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