I Human factors:

1. Is the release agent sprayed too much?

Due to the large amount of stripping gas, when the amount is too much, it is not burnt out before pouring, so that the volatile gas is wrapped in the surface of the casting. Therefore, under the same conditions, some workers will produce more pores during operation. The demoulding agent with small gas output is selected, the dosage is thin and uniform, and the mold is closed after burning.

2. Overflow trough and exhaust duct are not cleaned frequently?

3 is mold opening too early?

Is the mold preheated? Whether all parts are heated slowly and evenly, so that the surface temperature of the cavity and core is 150 ℃ ~ 200 ℃.

4 is there any isolation of products produced when the mold temperature is low at the beginning?

5 if there is no preheating device, whether to use aluminum alloy material to slowly push into the cavity for preheating or use other methods for heating?

6. Whether clean molten aluminum is taken and whether the oxide is injected into the pressure chamber?

7. When pouring, whether the spoon is close to the injection port of the pressure chamber to avoid splashing, oxidation or involvement in air cooling.

8. As soon as the liquid l is poured into the pressure chamber, whether the pressure injection is carried out immediately, and whether the temperature is reduced?.

9. Cooling and mold opening, whether the mold opening time is selected according to different products?

10 is there any fear of using normal die-casting pressure for fear of aluminum liquid flying out (water flying)? I dare not try to increase the specific pressure.?

11 does the operator strictly follow the die casting process?

12 is quantitative pouring adopted? How to determine the pouring volume?



II Factors of machine (equipment, mold, tooling):

It mainly refers to mold quality and equipment performance.

1 is the design of Die-casting Die reasonable, and will it lead to pores?

Reasons for die casting die:

1. Whether the choice of gate position and diversion shape are improper, resulting in the frontal impact and vortex of molten l entering the cavity. (reduce the injection speed and avoid vortex aeration)

2. Is the sprue shape poorly designed?

3. Is the inner gate speed too high, causing turbulence?

4. Is the exhaust blocked?

5. Is the mold cavity too deep?

6. Is the machining allowance too large? Penetrating the dense on the surface, exposing subcutaneous pores? The mechanical cutting allowance of die castings should be smaller, generally about 0.5mm, which can not only reduce the weight of castings, reduce the amount of cutting to reduce costs, but also avoid the exposure of subcutaneous pores. The allowance should not be greater than 0.5mm. In this way, there are basically no pores on the machined surface, because it is protected by a hard .

2 is the exhaust hole blocked and the air cannot be discharged?

3 is there too much lubricant in the punch, or is it burnt? This is also one of the sources of gas.

4. Gate position and diversion shape. Is there any overflow system on the parting surface closed by molten l first?

5 is the position of the inner gate unreasonable? The l after passing through the inner gate immediately impacts the mold wall and generates eddy current, and the gas is drawn into the l flow?

6. The position of the exhaust duct is incorrect, resulting in poor exhaust conditions?

7 is the area of the overflow duct large enough, blocked, and located at the last filling place? Is the exhaust part of the mold often cleaned? Avoid losing exhaust effect due to blockage of release agent.

8 is the mold temperature too low?

9. Is the channel turning smooth? Appropriately increase the inner gate?

10 is there an exhaust plug set at the deep cavity, or is the exhaust increased by splicing?

11 is there any part that is difficult to exhaust due to unreasonable die-casting design?

12 is the total cross-sectional area of overflow gate less than 60% of the total cross-sectional area of inner gate, and the slag removal effect is poor?

13 is it possible to increase the thickness of the inner gate to reduce the filling speed under the condition of satisfying good molding?

Is there any high speed of the inner gate, excessive turbulent movement, and serious involvement of l flow into gas?

15 is there any inner gate with too small sectional area and serious spraying?

Whether there is sequential filling to facilitate the discharge of cavity gas, and whether the sprue and runner have sufficient length?



III Material factors:

1. Is the composition of raw materials of suppliers well controlled? What is the iron content? (below 0.7)

2 is the purity of aluminum guaranteed?

3 is the secondary material (nozzle material) used too much and the slag removal action is not done well?

4. There is no excessive waste slag ladle added to the molten aluminum in the production process, which is poured together with the oxide skin during pouring?

5 does the company control the secondary use proportion of waste materials? How to implement? Who checks?

6 can scrap be added to the aluminum melt of important customer products?

7. Try to change the ratio of new material to recycled material?

8 is the charge clean?



IV Method factors:

It mainly refers to the pressure casting parameters and operation process.

1 is there any process parameter selected according to different products? (molten aluminum temperature 630-670 º C) reasonably select the die-casting process parameters, especially the injection speed. Adjust the starting point of high-speed switching.

2 is there any reduction in the moisture content of demoulding oil? Is there a mold release agent with low gas evolution?

3 is the alloy melting temperature too high?

4 how to measure the temperature of molten aluminum? Is the thermometer accurate?

5 is there a conversion point between the injection speed and the slow injection speed and the fast injection speed adjusted in time according to the product?

6 is there a large machine for casting small parts, and the filling of the pressure chamber is too small?



V Environmental factors:

Is the air humidity high in the die casting environment?

Generally, the hydrogen content in the surrounding air is not much, but if the relative humidity in the air is high, it will increase the solubility of the gas in the molten aluminum and form seasonal pores. For example, in the rainy season, due to the high air humidity, the phenomenon of pinholes during aluminum alloy smelting is more serious. Of course, when the air humidity is high, aluminum alloy ingots, smelting equipment, tools, etc. will also increase the adsorption of surface moisture due to the humidity of the air, so we should pay more attention to taking strong preheating and drying protective measures to reduce the generation of pores.

Explanation of terms and small data of aluminum die casting