Sheet Metal · 2022年6月5日

Knowledge of zinc alloy die castings

1 Subject content and scope of application
This standard specifies the classification, technical requirements, test methods, inspection methods, inspection rules, delivery conditions, etc. of zinc alloy die castings.
This standard applies to zinc alloy castings.
2 Quoted standards
GB 5678 Spectral analysis sampling method for cast alloys
GB 6060.1 Surface roughness comparison sample Casting surface
GB 6414 Dimensional tolerance of castings
GB/T 11350 Machining allowance for castings
GB/T 13818 Die-cast zinc alloy
3 Classification and classification of castings
3.1 Castings are divided into three categories according to the requirements of use (see Table 1).
category
Requirements
Test items
1
Parts subject to heavier loads
Parts with higher relative speed
Mechanical properties, dimensional tolerances, surface quality, chemical composition, other special requirements
2
Parts with medium load
Dimensional tolerance, surface quality, chemical composition, other special requirements
3
Parts and other parts subject to national interception
Surface quality, chemical composition, dimensional tolerance
3.2 The surface of castings is divided into three levels according to the scope of use (see Table 2).
level
symbol
Scope of use
Surface roughness
1
Y1
Surfaces with high technological requirements: plated, polished, and ground surfaces, mating surfaces that move relative to each other, and surfaces in dangerous stress areas
Ra1.6
2
Y2
Requires general or required sealing surface, anodizing and assembly contact surface, etc.
Ra3.2
3
Y3
Protective coating surface and fastening contact surface, painted surface, other surfaces
Ra6.3
3.3 Marking of castings.
3.4 Those that do not indicate the type, grade and dimensional tolerance of castings shall be handled according to the lowest grade of this standard.
4 Technical requirements.
4.1 The chemical composition of the alloy should meet the requirements of GB/T 13818.
4.2 Mechanical properties.
4.2.1 When using die casting samples for inspection, the mechanical properties of the castings should meet the requirements of GB/T13818.
4.2.2 When the die casting is used for inspection, the mechanical properties of the casting shall be negotiated between the supplier and the buyer.
4.3 The dimensional tolerances of castings do not include the casting inclination. For the regulations on the casting inclination, see Appendix A (reference parts).
4.3.1 The dimensional tolerances of castings produced in batches or in large quantities shall be implemented in accordance with the provisions of GB 6414.
4.4 The dimensional tolerances of castings do not include the casting slope.
4.5 Other requirements.
4.5.1 If required, the internal defects of castings shall be consistent with the standards or requirements agreed by the supplier and the buyer. The standards may include: X-ray film, photos, non-destructive testing or die casting section.
4.5.2 The gates, flashes, overflows, spacers, etc. of the castings should be cleaned. But it is allowed to leave traces.
4.6 The control of the air-tightness, hydraulic air-tightness of castings and items not listed in this standard shall be negotiated between the supplier and the buyer.
4.7 The supplier can impregnate and repair the castings under the conditions that cannot affect the use of the castings with the consent of the user.
5 Test method
5.1 Chemical composition.
5.1.1 The inspection method for the chemical composition of the alloy should comply with the provisions of 5.1.1 in GB/T 13818.
5.1.2 The sampling method of spectral analysis can refer to GB 5678.
5.2 Mechanical properties.
5.2.1 The inspection method of alloy properties should comply with the provisions in 5.2 of GB/T 13818.
5.2.2 When using casting samples, the cut location, size, and type shall be negotiated between the supplier and the buyer.
5.3 The surface roughness of castings is measured with GB6060.1 comparative sample block.
6 Inspection rules
6.1 Chemical composition. The inspection of the chemical composition shall comply with the provisions in 5.1 of GB/T 13818.
6.2 Mechanical properties.
6.2.1 The frequency of inspection of mechanical properties shall comply with the provisions in 5.2.1 of GB/T 13818.
6.3 The surface quality of castings should be inspected piece by piece according to the provisions of 3.2, 4.5.2, and 4.5.3.
6.4 The surface roughness of castings shall be tested in accordance with the provisions of GB 6060.1.
6.5 The geometric dimensions of the castings shall be determined by the supply and demand parties according to the number of random inspections in batches. The results of the high-level inspection must meet the requirements of 4.3.
7 Packaging, transportation and storage
7.1 The packaging of castings should ensure that they are protected from moisture and mechanical damage during transportation and storage time.
7.2 The mark of the package should include: name, quantity, alloy grade, inspection seal and delivery diary.
7.3 Transportation shall be negotiated by both parties.
Appendix A Casting slope of zinc alloy die casting (reference part)
The general casting gradient of the inner cavity of Al zinc alloy die castings is as follows, the casting gradient of the outer wall of the casting is 1/2 of the inner cavity degree, see Table Al.
Table Al
Inner cavity depth (mm)
≤6
>6-8
>8-10
>10-15
>15-20
>20-30
>30-36
Casting slope
2°30´

1°45´
1°30´
1°15´

0°45´
A2 The relationship between the hole diameter and the maximum depth of zinc alloy die-casting parts and the requirements of the casting slope are shown in Table A2
Table A2
The diameter of the hole
≤3
>3-4
>4-5
>5-6
>6-8
>8-10
>10-12
>12-16
>16-20
>20-25
Maximum depth
9
14
18
20
32
40
50
80
110
150
Casting slope
1°30´
1°20´
1°10´

0°50´
0°45´
0°40´
0°30´
0°25´
0°20´
A3 The minimum casting slope of zinc alloy die castings is shown in Table A3
Table A3
Casting cavity
0°20´
Outer wall of casting
0°10´
A4 The dimensional tolerances of zinc alloy die castings do not include the increase or decrease in dimensions caused by the casting inclination, but the minimum limit size of the casting must be guaranteed.
Appendix B
Table B Surface quality classification of zinc alloy die castings
Serial number
Defect name
Inspection scope
Surface quality level
illustrate
1 pole
2 poles
3 poles
1
Patterned pitted surface with colored spots
The area of ​​the three does not exceed the percentage% of the total area
5
25
40
2
Flow marks
Depth, mm ≤
0.05
0.07
0.15
The area is not greater than the percentage of the total area,%
5
15
30
3
Cold barrier
Depth, mm ≤
Not allowed
1/5 wall thickness
1/4 wall thickness
1. It is not allowed to exist at the same place at the corresponding place.
2. Length refers to defects
The length is not greater than the maximum contour size of the casting, mm
1/10
1/5
The amount that is not allowed to be exceeded on the surface
2 locations
2 locations
Distance from the edge of the casting, mm ≥
4
4
The distance between the two cold barriers, mm ≥
10
10
4
Bruise
Depth, mm ≤
0.05
0.01
0.25
Except on the pole surface, the gate position is allowed to double.
The area is not greater than the percentage of the total area,%
3
5
10
5
Sunken
Indentation depth, mm ≤
0.10
0.30
0.50
6
Adhesive traces
The entire casting is not allowed to exceed
Not allowed
1 place
2 locations
Percentage of surface area with defects,%
5
10
7
Incomplete corner depth
When the side length of the casting is ≤100mm
0.3
0.5
1.0
No more than 5% of the side length
When the side length of the casting>100mm
0.5
0.8
1.2
8
Average diameter≤3mm
The number of defects per 100cm² does not exceed the number
Not allowed
1
2
Two kinds of bubbles are allowed to exist at the same time, but no more than 3 large bubbles, no more than 10 in total, and no less than 10mm margin
The whole casting does not exceed the number
3
7
Distance from the edge of the casting, mm ≥
3
3
The height of the bubble convex considering the circumference, mm ≤
0.2
0.3

To

To

To

To

To

To

To

Average diameter>3-6mm

The number of defects per 100cm² does not exceed the number

Not allowed

1

1

To

The whole casting does not exceed the number

1

3

Distance from the edge of the casting, mm ≥

5

5

Bubble height, mm ≤

0.3

0.5

9

Ejector mark

The depth of the recessed casting does not exceed the wall thickness at that place

Not allowed

1/10

1/10

To

Maximum concave amount

0.4

0.4

Height of protrusion, mm ≥

0.2

0.2

10

Reticulated traces

Convex or concave, mm ≤

Not allowed

0.2

0.2

To

11

The sum of various defects

The area does not exceed the percentage of the total area%

5

30

50

The representation method of the brand. Die-cast zinc alloy grades are composed of the chemical symbols of zinc and main alloying elements. The main alloy elements are followed by numbers indicating their respective percentages (the nominal percentage is the average percentage of the element and the trimmed value). In front of the alloy grades, the letter “Z” (the first letter of the Chinese pinyin of the word “cast”) is used to indicate that it is used for pressure casting. Representation of the code number The alloy code in this standard consists of the letters “Y” and “X” (the first letter of the two Chinese pinyin of “pressure” and “zinc”) and the following three Arabic numerals. The first two digits after YX represent the nominal percentage content of the chemical element aluminum in the alloy, and the third number represents the nominal percentage content of the chemical element copper in the alloy.

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