Technical requirements of quality control for metal parts to be coated
Some standard content:
National Standard of the People's Republic of China
Technical requirements of quality control for metal parts to bc coated 1 Subject content and scope of application
This standard specifies the quality requirements for metal parts before plating. GB/T 12611-90
This standard applies to the quality control and acceptance of metal parts before electroplating, chemical plating, chemical passivation, chemical oxidation, electrochemical oxidation and other plating.
2 Reference standards
GB197 Ordinary thread tolerances and fits (diameter 1~355 mm) G1172 Conversion values of hardness and strength of ferrous metals GR5267 Electroplating layer of threaded fasteners
3 Quality requirements before plating
3.1 The oil seal of the parts should be removed before key plating. After removing the seal, the surface of the cold (parts) should be free of oil, paint, metal chips, color from mechanical marking and other excess materials.
3.2 The (parts) to be keyed should be free of mechanical deformation and mechanical damage, and free of defects such as oxide scale, spots, pits, bumps, burrs, scratches, etc. that affect the quality of the coating and the performance of the product. 3.3 For any parts that have matching requirements specified in the design, the technical dimensions of the coating thickness must be reserved before plating, and the dimensions should be inspected and accepted 100% according to the provisions of the above-mentioned technical documents. 3.4 For any threaded parts that need to be plated, sufficient margins should be reserved according to G3197 and Appendix R of GB5267 and the selected coating thickness. 3.5 Metal-rubber and metal-plastic composite parts, parts connected by threads or combined by pressing, overlapping, riveting, lap welding, spot welding, etc., ferrous metal and non-ferrous metal, fine-machined parts and rough parts, powder metallurgy and other metal parts, etc., when special plating is required, it should be first submitted to the technical department for consultation and the technical acceptance specifications agreed by both parties should be formulated. 3.6 For metal-rubber and metal-material composite parts that need special plating, the rubber or plastic part should not be broken or scratched; there should be no burrs, debris and unbonded parts at the junction of rubber or plastic and metal exposed parts; there should be no rubber or plastic residues on the surface of the metal exposed part. When collecting, visual inspection should be carried out under conditions of sufficient light or good artificial lighting. If necessary, a 3-5x magnifying glass can be used for inspection.
3. Before plating, process holes should be left in the parts that do not affect the use to facilitate the discharge of gases and slag. 3. There should be no excess solder and slag in the welded parts. The weld should be cleaned by sandblasting or other methods; the weld chain should be free of defects such as pores and unwelded wheels. 3.9 The workpiece after heat treatment should be surface cleaned, and no defects that can be completely removed by technology are allowed. Oxide scale and residues (such as salt, alkali, molding sand and sintered products caused by oil stains not completely removed from the surface of the piece before heat treatment, etc.); a slight oxidation color is allowed, but rust is not allowed. 3.10 The surface of castings, forgings and hot-rolled pieces that are not machined should be sandblasted or shot peened. Hot-rolled pieces with a material tensile strength less than or equal to 1050 MPa can also be pickled to remove the oxide scale. Approved by the State Administration of Technical Supervision on December 18, 1990, 1991:12 01 Implementation
GB/T 12611—90
3.11 The surface after sandblasting should not have residual scale, rust leakage, sand, fingerprints, etc. All high-strength steel parts (components) that have been sandblasted should start plating (including pretreatment) within 1 hour. 3.12 Parts (components) and springs that have been ground or inspected by flaw detection should be free of residual magnetism, magnetic powder and fluorescent powder, etc. 3.13 All parts (components) that have been machined, milled, cold formed, cold stretched, and cold corrected, when the maximum tensile strength of the material is greater than 1050MPa, except for surface blasting parts, should be heat treated to eliminate residual stress according to the conditions specified in Table 1. Table!
Maximum tensile strength of material, MPa
>1050～1450
1 4501800
Heat treatment temperature and humidity, h
190~-210
190~210www.bzxz.net
193-~214
3.13.1 When only the minimum tensile strength of the material is known, the maximum tensile strength can be determined according to Table 2. Table 2
Material tensile strength minimum value
1000~1400
1401～↓750
Heat treatment time, h
Material tensile strength maximum value
1 050~1450
14511800
3.13.2 When the hardness value of the material is known, the maximum tensile strength should be found according to GB1172. 3.13.3 Before stress relief heat treatment, the grease on the surface of the parts should be cleaned. 3.14 The heat treatment of the surface quenching parts to eliminate residual stress should be kept at 130-150 degrees Celsius for not less than 5 hours. If the surface hardness of the base metal is allowed to decrease, a higher temperature and shorter time heat treatment can also be used. 3.15 The steel parts to be plated should be accompanied by a certificate of residual stress relief heat treatment. 3.18 When shot peening is required, shot peening should be carried out after residual stress relief heat treatment. 3.17 When special requirements are made for stress relief heat treatment after shot peening, the temperature of residual stress relief heat treatment shall not exceed 220°C. 3.18 Except for the parts (parts) whose design has specified the surface roughness value R and the fillet value, in order to ensure the quality of the coating, the surface roughness value R of the parts (parts) before plating shall be raised. and fillet value shall comply with the provisions of Table 3 Table 3
Coating type
Engineering plating, porosity inspection required
Engineering chrome plating, porosity inspection not required
Decorative chrome plating
Ceramic anodizing
Palladium plating, plating
High quality anodizing, insulating anodizing
Anti-carburizing, anti-nitriding, anti-corrosion and copper plating or plating Surface roughness value before plating
Not more than,
Specification brightness requirements determined
Note: ①This table is based on the basis of not polishing, grinding and other finishing after micro-plating. (2) Exceeding the provisions of this table and 3.19 When specified, the fillet value is agreed upon by both the supplier and the buyer. If the surface roughness value of the part is specified on the drawing, that is, the final surface roughness value of the part, the surface roughness value before plating shall not be less than half of the roughness value marked on the drawing. GB/112611
320 Unless otherwise specified, plating shall be carried out after all mechanical processing is completed. 4 Other requirements
4.1 For products that need to be destructively tested after plating, when the batch is small or its shape is not suitable, or the price is too competitive, it shall be necessary to have process samples and test pieces with the same material (same furnace batch) as the part, the same surface warpage, the same heat treatment state, and similar geometric dimensions. The number is determined according to the test items and sampling quantity requirements. The sample can also be replaced by the scrapped parts (parts) with out-of-tolerance machining dimensions in the batch. 4.2 The parts to be plated must be boxed or special workstation equipment must be used. Surface roughness values ≤ 0.8um and precision parts should be packed in special packaging boxes and packaged separately to avoid damage to the parts and corrosion of the parts during transportation. 4.3 Forgings, castings, welded parts, stampings or raw materials with defects allowed by the corresponding technical standards can be plated. However, the defects in the bonding layer caused by these defects are not considered as quality defects of the plating process. Additional notes:
This standard was proposed by the National Technical Committee for Standardization of Metallic and Non-metallic Coatings. This standard was drafted by the National Technical Committee for Standardization of Metallic and Non-metallic Coatings. This standard was drafted by the Seventh and Eighth Institute of the Ministry of Aerospace Industry. The authors of this standard are Jiang Wanqing and Yang Xuekai.
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