This standard specifies the technical conditions for the coating, coating quality and inspection of organic coatings for typical mechanical products used in hot and humid environments. This standard applies to typical mechanical products such as machine tools, agricultural machinery, tractors, electrical products, instruments and meters, cranes, port machinery, loading and unloading machinery, mining machinery, and their sheet metal parts, castings, non-ferrous metal parts and non-metallic parts. This standard can also be used as a basis for the coating quality and inspection of the above products used in sub-hot and humid environments. JB/T 7501-1994 Technical conditions for organic coatings of typical mechanical products in hot and humid environments JB/T7501-1994 Standard download decompression password: www.bzxz.net
This standard specifies the technical conditions for the coating, coating quality and inspection of organic coatings for typical mechanical products used in hot and humid environments. This standard applies to typical mechanical products such as machine tools, agricultural machinery, tractors, electrical products, instruments and meters, cranes, port machinery, loading and unloading machinery, mining machinery, and their sheet metal parts, castings, non-ferrous metal parts and non-metallic parts. This standard can also serve as a basis for the coating quality and inspection of the above products used in sub-humid hot environments.

Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Organic Coatings of Typical Mechanical Products in Hot and Wet Environments
1 Subject Content and Scope of Application
JB/T7501-1994
This standard specifies the technical conditions for the coating, coating quality and inspection of organic coatings of typical mechanical products used in hot and humid environments. This standard is applicable to organic coatings of typical mechanical products such as machine tools, agricultural machinery, traction machines, electrical products, instruments and meters, cranes, port machinery, loading and unloading machines, mining machinery, and their sheet metal parts, castings, non-ferrous metal parts and non-metal parts. This standard can also serve as the basis for the coating quality and inspection of the above products used in sub-hot and humid environments. 2 Reference standards
Determination of paint film adhesion
GB1720
GB1727
GB1729
GB1730
GB1732
General preparation of paint films
Determination of paint film color and appearance
Determination of paint film hardness Pendulum damping test
Determination of paint film impact resistance
GB1743
Determination of paint film gloss
GB1764
GB1765
GB1766
GB1767
GB1771
Determination of paint film thickness
Determination of paint film preparation method for resistance to moisture and heat, salt spray and weathering (artificial acceleration) Weathering resistance rating method for paint films Method
Determination of weathering resistance of paint film
Determination of neutral salt spray resistance of paints and varnishesSafety regulations for painting operationsPainting processVentilation and purificationGB6515
GB6807
Technical conditions for phosphating treatment of steel workpieces before paintingGB8264
Technical terms for painting
GB8923
JB/Z236
Rust grade and rust removal grade of steel surface before paintingTest method for degreasing degree of steel parts before painting:Technical conditions for painting of export machine tools
ZBJ50012
3 Terms
3.1 Hot and humid environment
An environment with air temperature greater than or equal to 20℃ and relative humidity greater than or equal to 80% for more than two consecutive months each year and 12 hours or more each night.
According to the use and transportation conditions of mechanical products, the humid and hot environment is classified according to the severity of corrosion. See Table 1: Approved by the Ministry of Machinery Industry on October 25, 1994
Implementation on October 1, 1995
Type
Mild
Moderate
Severe Acid
Coating
Classification Code
JB/T7501—1994
Table 1 Classification of Severity of Corrosion in Humid and Hot Environment
Environmental Characteristics
Indoor areas without obvious pollution (including outdoor places with good shielding conditions) Areas with chemical gas pollution but no serious industrial agglomeration, high temperature and humidity, long monthly sunshine time Typical industrial agglomeration areas or areas near coastal areas, marine and chemical atmospheres with obvious ammonia, sulfur dioxide, acid, alkali, salt, etc.
Continuous film layer obtained by coating (see Article 5.1 in GB8264). 3.3 Coating
A continuous film formed by applying one or more coats of coating (see 5.2 in GB8264). Coating classification and code
In product drawings and technical documents, the marking method of mechanical product coatings is specified as follows: C-□
Base material code
Environmental type code
-Coating
Mechanical products
-Mild hot and humid environment
Environmental type code: L——
MO-Moderate hot and humid environment
Base material code: P-
-Severe hot and humid environment
Steel sheet metal parts
CA—Steel castings
NF Non-ferrous metal parts
NM-——Non-metallic parts
MC-LP
Code example: 1.
Indicates coating for steel sheet metal mechanical products in mild hot and humid environment. 2.
MC-S-CA
Indicates coatings for steel casting mechanical products in severe hot and humid environments. 5. Organic coating design
Organic coating design should consider factors such as the coated product, coating characteristics, use environment and construction conditions. 5.1 Coated product design
The coated product design should consider product material, surface state, structure, etc. The coated product design must meet the anti-corrosion design requirements, minimize surface defects, gaps and galvanic contact, etc., in order to obtain a uniform coating film and avoid the accumulation of corrosive media. 5.2 Coating system design
5.2.1 Selection of coating varieties
When selecting coating varieties, the following should be considered:
The purpose and requirements of coating;
b. Technical performance of coating varieties,
Material of coated products;
Use environment and service life of coating film;
Coating construction and drying and curing conditions;
f. Economic accounting, etc.
5.2.2 Coating matching requirements
JB/T7501—1994
Coating matching refers to the matching of primer, putty, intermediate sealer, topcoat and varnish into a composite coating. Coating matching should consider:
A. Meet the anti-corrosion requirements;
Each coating should have good compatibility and synergy; b.
c. Have good construction performance.
For the matching of common primers and topcoats for mechanical products in hot and humid environments, please refer to Appendix C (reference). 5.2.3 Coating film thickness
The coating film thickness is determined by the coating film use environment, the service life of the coated product and the coating performance. The coating film thickness of steel sheet metal parts shall not be less than 60um, and the coating film thickness of steel castings (excluding putty layer) shall not be less than 100μm. 6 Main technical requirements for coating
6.1 Pre-coating treatment
6.1.1 Pre-coating treatment of metal surface
6.1.1.1 Surface condition of coated parts: The metal surface of the coated parts should be flat, and no bulges, sand holes, burrs, or uneven welds are allowed. 6.1.1.2 Degreasing: The metal surface of the coated parts should be thoroughly cleaned, and no greasy dirt is allowed. For the method of checking whether the metal surface is clean, see Appendix A (Supplement). In addition, for the method of checking whether the surface of steel parts is clean, see JB/Z236.6.1.1.3 Rust removal: Rust removal can be done mechanically or chemically. If chemical rust removal is used, there should be no visible scale, rust, or excessive corrosion on the coated parts, and the surface should be uniform in color. See Table 2 for the requirements for mechanical rust removal levels on steel surfaces under different environments. Table 2 Requirements for mechanical rust removal on steel surfaces
Environmental code
Requirements for mechanical rust removal on steel surfaces before painting≥St3,≥Sa2
≥Sa2
Sa2K
For the evaluation of steel rust removal and the expression of rust removal, see GB8923. Rust removal of castings (including steel and non-ferrous metals) should be done by mechanical methods, and avoid the use of chemical pickling methods. 6.1.1.4 Conversion film treatment: After the surface of the coated part is cleaned, the surface shall not be re-contaminated or rusted before the conversion film treatment. After cleaning, steel sheet metal parts should be phosphated immediately. The technical conditions for phosphating treatment are shown in GB6807. Non-ferrous metal parts can be treated with chemical oxidation, electrochemical oxidation or other conversion films. 6.1.1.5 When the workpiece cannot be phosphated, a phosphating primer should be applied with a thickness of (6~10) um, and then a matching primer should be applied after solidification. After the non-ferrous metal parts are degreased and rusted, if phosphating primer is used, the matching primer should be applied after curing. Castings are generally not treated with conversion film.
6.1.1.6 After the metal surface is treated before coating, the primer should be applied as soon as possible to avoid re-contamination or rust. 6.1.2 Pre-treatment of non-metallic surfaces
6.1.2.1 Pre-treatment of plastic surfaces: The surface of plastic products should be treated with stripping agents, physical and chemical surface modification, stress relief and dust removal.
6.1.2.2 Pre-treatment of wooden surfaces: The wooden surface should be flat and smooth, free of dirt and resin substances, and the moisture content of the wood board should be 536
8%~12%.
6.2 Paint application
JB/T7501—1994
6.2.1 Application environment: If there is no special provision, the application should be carried out under the condition of temperature (5~35)℃ and relative humidity not more than 80%. For ventilation and purification requirements of the construction environment, please refer to GB6515.6.2.2 Paint: The performance of the paint should be tested before application and can only be used after passing the test. The construction performance test should be carried out during the application to ensure the quality of the application.
6.2.3 Paint application method: Various methods can be used, which are determined by the product type, shape, size, and performance of the paint. 6.2.4 Apply primer: The primer should be complete and no missing paint, pinholes, sagging, bubbles, wrinkles or other defects are allowed. 6.2.5 Apply putty; When puttying is required, the putty should be applied on the primer, and the second layer should be applied after the previous layer of putty is dry. Under the condition of ensuring flatness, the thickness of putty should be as thin as possible or no puttying should be done. 6.2.6 Apply intermediate sealant: After applying primer, intermediate sealant can be applied if necessary; intermediate sealant must be applied after applying the scraper. 6.2.7 Apply topcoat
6.2.7.1 After applying primer or intermediate sealant, topcoat should be applied as soon as possible. If topcoat cannot be applied immediately, the bottom layer should not be contaminated or rusted when applying again.
6.2.7.2 The drying method of the coating shall be carried out in accordance with the method specified by the coating type and model requirements to achieve the specified hardness. 7
Coating quality index
The main quality indexes of organic coatings for mechanical products used in hot and humid environments are shown in Table 3. 537
Coating code
Coating characteristics
Film appearance
Adhesion
Impact strength/
(kg - cm)
Weather resistance"
Salt spray resistance
Performance
Heat-proof
Performance
MC-LP
Coating for sheet metal in mild mixed heat
environment
1 year comprehensive grade"Excellent
6 cycles comprehensive gradeExcellent
21 cycles
Comprehensive gradeGood
Above
MC-LC
Coating for castings in mild damp heat
≥0.4
≤2 grade
1 year comprehensive grade
Good or above
6 cycles comprehensive
Good
or above
21 cycles
Comprehensive gradeMedium
or abovebzxZ.net
MC-L-NF
Mild hot and humid
EnvironmentNonferrous metal
Coating for parts
1 year comprehensive grade
Excellent
6 cycles comprehensive
Excellent
21 cycles
Comprehensive gradeGood
or above
1) Weathering resistance test site is Guangzhou and Wuhan exposure field. 2) Comprehensive grade refers to protective comprehensive grade. Table 3 Main indicators of organic coatings for mechanical products in hot and humid environments MC-MO-P
Coatings for sheet metal in moderate hot and humid environments
MC-MO-C
Coatings for castings in moderate hot and humid environments
MC-MO-NF
Coatings for nonferrous metals in moderate sensible heat environments
MC-SP
Coatings for sheet metal in severe hot and humid environments
The paint film is plump, smooth, evenly colored, and has no obvious defects ≥0.5|| tt||1st level
1.5-year comprehensive
excellent grade
9-cycle comprehensive
excellent grade
21 cycles
comprehensive grade good
and above
1.5-year comprehensive
good grade and above
9-cycle comprehensive
excellent grade
and above
21 cycles
comprehensive grade medium
and above
1.5-year comprehensive
excellent grade
9-cycle comprehensive
excellent grade
21 cycles
comprehensive, etc. Good grade
and above
2 years comprehensive grade
Excellent grade
12 cycles
Excellent comprehensive grade
21 cycles
Excellent comprehensive grade
MC-$-C
For castings in severe damp and hot
environment
Coating
≥0.5
Grade 1
2 years comprehensive grade
Good grade
and above
12 cycles
Excellent comprehensive grade
and above
21 cycles
Excellent comprehensive grade
and above
MC -S-NF
Harsh hot and humid environment
Nonferrous metal
Coating for parts
2 years
Excellent comprehensive grade
12 cycles
Excellent comprehensive grade
21 cycles
Excellent comprehensive grade
MC--NM
Nonmetallic coating for various hot and humid environments
Strong adhesion
JB/T7501—1994
Coating film inspection
JB/T7501—1994
In principle, it is carried out on the cured coating film. The inspection surface can be the product or the test plate with the same process conditions as the product, depending on the specific inspection items.
8.1 Coating film thickness: in accordance with the provisions of GB1764. Color appearance: in accordance with the provisions of GB1729. 8.2
8.3 Gloss: in accordance with the provisions of GB1743. Adhesion: in accordance with the provisions of GB1720. 8.4
8.10
Impact resistance: in accordance with the provisions of GB1732. Hardness: in accordance with the provisions of GB1730.
Weather resistance: in accordance with the provisions of GB1767. Salt spray resistance: in accordance with the provisions of GB1771. Heat and humidity resistance: in accordance with the provisions of Appendix A2 of ZBJ50012. Paint film rating: The paint film rating methods for weather resistance, salt spray resistance and heat and humidity resistance shall be in accordance with the provisions of GB1766. 539
JB/T7501—1994
Appendix A
Method for checking whether the surface is clean
(Supplement)
Spray a wet layer of distilled water on the cleaned surface or immerse the cleaned parts in distilled water, take them out, and observe within 20 seconds. If a continuous water film can be maintained, the oil is completely removed. If the water film is broken, it is considered that it is not clean. Appendix B
Application scope of various coatings in typical mechanical products (reference)
For examples of the application scope of various coatings in typical mechanical products, see Table B1. B1
Table B1 Examples of the application scope of various coatings in typical mechanical products Layer code
MC--P
MC--CA
Application range
Machine tools, electrical appliances, tractors
Sheet metal parts in products
Machine tools, tractors
Castings in products
Pulley boxes of transmission mechanisms, spindle gearboxes, knob boxes, protective covers, operating covers, control cabinet outer walls, high and low voltage cabinet shells, switch cabinet frames, cabs, fenders, engine covers, instrument covers, cover plates, support frames, instrument panels, seat frames, etc. Machine tool beds, bases
For commonly used primers and topcoats for hot environment mechanical products, see Table C1. Surface
A04-7,9
A04-81
A16-51
B04-54
B16-51
G04-2
G04-9
G52-31
H04-1
H04-2
H04-10
H52-1
H54-32
H55-11
Various colors amino drying enamel
Various colors amino matte drying Enamel paint
Various colors of nitrogen-based drying hammer paint
Various colors of acrylic drying enamel
Various colors of acrylic acid drying hammer paint
Various colors of perhydroethylene enamel
Various colors of perfluoroethylene external enamel
Polyurethane modified perchlorethylene enamel
Various colors of perchlorethylene anticorrosive paint
Various colors of epoxy enamel
Various colors of epoxy nitro enamel
Epoxy amino baking paint
Epoxy asphalt paint
Epoxy phenolic anticorrosive paint
White ring Epoxy oil-resistant baking paint
Epoxy polyurethane baking water-resistant paint
Closed type epoxy polyurethane paint
Model
H06-2
H06-2
H06-2
H06-2
H06-2
H06-2
H06-2
H06-2
G06-4
H06-2
H06-2
H11-51|| tt||H06-13
H52-12
H06-2
H55-2
Appendix C
Commonly used primers and topcoats for mechanical products in hot and humid environments (reference parts)
Commonly used primers and topcoats for mechanical products in hot and humid environments Table C1
Primer 1
Iron red epoxy ester primer
Iron red epoxy ester primer
Iron red epoxy ester primer
Iron red epoxy ester primer
Iron red epoxy ester primer Paint
Iron red epoxy ester primer
Iron red epoxy ester primer
Iron red epoxy ester primer
Iron red perchlorethylene primer
Iron red epoxy ester primer
Iron red epoxy ester primer
All kinds of epoxy ester drying electrophoretic paint
Epoxy asphalt primer
Epoxy phenolic anticorrosive baking paint
Iron red epoxy ester primer
Epoxy polyurethane water-resistant primer
Enclosed epoxy nitrogen ester primer
Model
G06-4
S06-2
S06-2
B06-2
Supporting primer 2
Name
Iron red aluminum powder epoxy polyamide primer
Iron red aluminum powder epoxy polyamide primer
Iron red aluminum powder epoxy polyamide primer
Perchlorethylene primer
Iron red perchlorethylene primer
Iron red polyurethane primer
Iron red polyurethane primer
Yellow acrylic primer
Type No.
G06-4
G06-4
Matching primer 3
Iron red perchlorethylene primer
Iron red peroxide primer
JB/T7501-1994
Model
Q04-31,34
S04-1
S16-30
Various colors of nitro enamel
Turbulent urethane enamel
Polyurethane hammer paint
Polyvinyl chloride paint
Ammonia Chemical rubber paint
Acrylic paint
Polyurethane paint
Model
H06-2
H06-2
H06-2
Matching primer 1
Iron red epoxy ester primer
Iron red epoxy ester primer
Polyvinyl chloride primer
Inorganic zinc-rich primer
Additional instructions:
This standard is proposed and managed by the Wuhan Materials Protection Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Wuhan Materials Protection Research Institute. The main drafters of this standard are Zhao Yingying, Fang Yisan and Xia Chunlan. Table C1 (end)
Model
Matching primer 2
Name
Iron red aluminum powder epoxy polyamide primer
Epoxy zinc-rich primer
Model
Matching primer 3
Coat epoxy on primer
Mica iron intermediate layer
Recommended coating for plastic product surface
JB/T7501-1994
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