This standard specifies the marking, classification, selection basis, technical requirements and test methods of chromium, nickel and zinc surface coatings for electroplating of sewing machine parts. This standard is applicable to electroplated sewing machine parts (hereinafter referred to as "plated parts") with protective and decorative metal substrates. Other coatings, plating types and (or) engineering electroplated parts should also be used as a reference. QB/T 1572-1992 General Technical Conditions for Electroplating of Sewing Machine Parts QB/T1572-1992 Standard download decompression password: www.bzxz.net

Light Industry Industry Standard of the People's Republic of China
General Technical Conditions for Electroplating of Sewing Machine Parts
1 Subject Content and Scope of Application
QB/T1572—1992
This standard specifies the marking, classification, selection basis, technical requirements and test methods for the surface coatings of chromium, nickel and zinc on sewing machine parts subjected to electroplating.
This standard applies to electroplated sewing machine parts (hereinafter referred to as "plated parts") with protective or decorative metal substrates. Other coatings, plating types and (or) engineering electroplated parts should also be used as a reference. 2 Referenced Standards
GB/T1238 Methods for Representing Metal Coatings and Chemical Treatments GB/T 2828
Batch Inspection Count Sampling Procedure and Sampling Table (Applicable to Inspection of Continuous Batch) GB/T 2829
Periodic inspection counting sampling sequence and sampling table (applicable to the inspection of production process stability) Thickness test method of metal coating and chemical treatment layer of light industrial products Metallographic microscope method GB5929
GB5930
GB5931
GB5933
GB5934
GB5938
GB5944
Friction test method of metal coating of light industrial products Spot method Thickness test method of metal coating and chemical treatment of light industrial products Test methods Beta-ray backscattering method Method for testing the bonding strength of metal coatings on light industrial products Method for measuring the hardness of metal coatings on light industrial products Microhardness method Corrosion resistance test of metal coatings and chemically treated layers on light industrial products Neutral salt test (NSS) method Evaluation of corrosion test results of metal coatings on light industrial products GB/T4955 Measurement of thickness of metal coatings Anodic dissolution Coulometric method 3 Terms
Main surface
Certain surfaces on parts before and after electroplating, the coating on this surface plays a major role in the appearance and (or) performance of the parts.
4 Technical document marking regulations
Technical requirements for plated parts in technical documents such as product drawings and quality standards should be clearly marked as required, and should include all or part of the following requirements:
4.1 The technical conditions of the coating should meet the requirements of the plated parts in Table 1. 4.2 When it is necessary to specify the electroplating mark, the symbols and representation methods specified in GB/T1238 shall be used uniformly, and all or part of the following contents shall be indicated in the relevant technical documents: plating method;
plating characteristics;
plating name and thickness;
pre-plating preparation and post-plating treatment.
Approved by the Ministry of Light Industry of the People's Republic of China on August 31, 1992
Implementation on April 1, 1993
4.3 Main surface of plated parts
4.4 Roughness of substrate surface (before plating)
4.5 Other requirements
Classification and selection basis of plated parts
5.1 Classification of plated parts
Classify according to the method specified in Table 1.
5.2 Selection shall be based on
2-1992
QB/T 1572
Select classified plated parts according to Appendix A (reference parts) of this standard and the factors that should be considered for parts. Table 1
Surface coating type
Coating technical requirements
6.1 Appearance
Quality requirements
Class I chrome-plated parts
Class I chrome-plated parts
Class I chrome-plated parts
Class N chrome-plated parts
Class I chrome-plated inserts
Class I chrome-plated inserts
Class I galvanized parts
Class I galvanized parts
Class I galvanized parts
6.1.1 The plated parts shall be free of rust and peeling, and the main surface shall be free of obvious bubbles, spots, pinholes and burrs, and shall be smooth, flat and of basically uniform color.
6.1.2 The surface of the plated parts shall meet the requirements for the coating characteristics in the technical documents provided by the purchaser. 6.2 Roughness
The surface roughness of the plated parts shall meet the requirements of Table 2. For the plated parts with forging surface processing method, the roughness is not limited by Table 2. Table 2
Classification Plated Parts
Roughness R.
Surface coating thickness, m
Corrosion resistance
Test time, h
Corrosion resistance grade
Classification Plated Parts
6.3 Coating thickness
Roughness R.
QB/T 1572- 1992
Continued Table 2
Surface coating thickness, μm
Corrosion resistance
Test time, h
Corrosion resistance grade
The surface coating thickness of the plated parts shall meet the requirements of Table 2, and the type and thickness of the bottom and middle layers shall meet the requirements specified in the technical documents provided by the purchaser.
6.4 Hardness
The hardness of household sewing machines should be greater than 300HV0.1, and the hardness of industrial sewing machines should be greater than 450HV0.1.6.5 Adhesion
After testing according to the method specified in Article 7.5 of this standard, there is no separation between the coating and the plated parts or between the coatings. 6.6 Corrosion resistance
After testing according to the method specified in Article 7.6 of this standard, the corrosion resistance of the plated parts should not be lower than the corrosion resistance level specified in Table 2. 7 Test method
7.1 Appearance inspection
Under the light of 600±200lx, the inspection distance is 300mm, and the visual judgment is made. 7.2 Roughness test
One of the following methods is determined by the purchaser and the electroplating manufacturer. 7.2.1 Use the physical object or standard sample agreed by both parties within the validity period for comparative measurement. 7.2.2 Use various types of profilometers that meet the requirements to measure 8 locations on the main surface of the test piece. For test pieces with smaller main surfaces, measure at least 5 times, and take the arithmetic average.
Note: When the main surface of the test piece is a stamped and embossed pattern, the concave part is not used as the test part. 7.3 Thickness test
7.3.1 Method
7.3.1.1 Coulometric method
As long as the main position of the plated parts can be contacted by a steel ball with a diameter of $20mm, they can be tested with an automatic thickness gauge based on the coulometric method, and the method specified in GB/T4955 can be used. 7.3.1.2 Other methods
All methods specified in GB5928~5931 can be used. 7.3.2 Preparation before testing
Wipe the tested surface clean with alcohol or gasoline, and remove the passivation film according to the method specified in the instrument instructions before testing. 7.3.3 Test location
Within the main surface range.
7.3.4 Thickness value
The average thickness of the measured surface coating is the thickness value of the coating. 7.3.5 Result review
When there is a dispute over the thickness measurement result, the Coulomb method shall be used for arbitration inspection. 7.4 Hardness test
Perform according to the method specified in GB5934.
7.5 Adhesion test
QB/T1572-1992
Select one of the methods specified in Table 3 according to the geometric shape and key type of the test piece, and test according to GB5933. Table 3
7.6 Anti-magnetic ability test
7.6.1 Method
Wire shape
Magnetic bending method, heating method
Bending method, heating method
Brushing method
Perform according to the provisions of GB5938.
7.6.2 Spraying time
The test time specified in Table 2 of this standard is the spraying time. 7.6.3 Test surface
Flake
Bending method, heating method
Bending method, heating method
Brushing method, magic rubbing method, scratching method
Other shapes
Heating method, filing method
Heating method, filing method
Brushing method, friction method
The test surface is within the main surface of the plated part, but does not include the traces of the electroplating hanger. At the same time, the test is carried out within the 1mm range around the hole and the edge. The test surface area can be composed of a single or multiple plated test surfaces, and the total area is not less than 1dm. The reduced total area of ​​the parts is tested in proportion.
7.6.4 Evaluation of corrosion resistance level
After the corrosion test is completed, immediately rinse the residue of the corrosive medium with water, or carefully scrub with wet cotton (do not damage the plating layer), and evaluate the corrosion resistance level according to GB5944 and Table 4. Table 4
Number of rust points, pieces/m
>4～8
>8～16
7.6.5 No rating
Pit corrosion resistance level
No rating when there are one or more corrosion points with an area greater than 2.5mm* penetrating the plating layer. 95
A1 Overview
QB/T 1572—1992
Appendix A
Category Selection Basis of Plated Partswww.bzxz.net
(Reference Parts)
A1.1 The diversification of sewing machine varieties has led to more types of parts appearing in different positions of various models. For the parts that need to be electroplated, their technical requirements are determined, that is, which classification of plated parts is selected. It is impossible to make separate provisions for all specific models and plated parts in the general technical conditions. Therefore, this appendix proposes the following considerations as the basis for selecting classified plated parts, and as the reference principle for selecting classified plated parts when determining the technical requirements of plated parts. Position in the whole machine, whether it is an exposed part (including common spare parts and easy-to-install and disassemble parts); a. Functional requirements; c. Working state, d. Shape and size. A1.2 After the classified plated parts selected according to the method of this appendix are considered to have improved and (or) increased technical requirements for functions and environments, the content should be noted in the relevant technical documents. A2 Example Table A1 gives an example of the applicable basis for classified plated parts for reference. Table A1
Protective and
Decorative
Protective
Exposed parts at the head
Exposed parts other than the head
Non-exposed parts at any part
Working state
Continuous
friction by sewing materials or sewing lines or regular work
Parts with large shape and size, obvious main surface appearance, generally can be plated
Parts with relatively small shape and size
Small parts with small main surface and difficult to plate, such as thin wire, small thread, gasket-shaped parts
Large shape and size, obvious appearance
Small parts with small size and difficult to hang plating are not limited in shape, and the appearance is generally required to be small parts connected or fastened with Class I and Class I nickel plating. The shape is not limited. Class I and Class I chrome-plated parts. Class I chrome-plated parts. Class I chrome-plated parts. Class I chrome-plated parts. Class I plated inserts. Class IV chrome-plated parts. Class I and Class I plated inserts. Class I nickel-plated parts. Class I galvanized parts. Class I plated inserts. Class I galvanized parts. Class I plated inserts. Class I galvanized parts. Additional instructions: QB/T1572--1992. This standard is proposed by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Sewing Machine Standardization Center. This standard was drafted by Guangzhou South China Sewing Machine Industry Company. The main drafters of this standard are Wang Guangchi, Xu Wenjuan and Lu Yan. From the date of implementation of this standard, the former Ministry of Light Industry standard QB625--1975 "Technical Conditions for Electroplating of Household Sewing Machines" will be invalidated.
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