Die-casting die cracking is quite terrible, the situation of cracking occurs:

1. High temperature during die casting process (additional cooling system as far as possible).

2. The spraying of release agent may be unreasonable in the process of die casting.

3. The heat treatment of the die is unreasonable, and the hardness (hardness should be no less than HRC-47).

Die-casting die cracking is quite terrible, which ghosts are doing it!

4. Poor raw materials for die steel

Pre-cracking is usually due to the high forging temperature (commonly known as over-burning) which is an irreparable defect. Therefore, the starting temperature in the process of blank manufacturing should be strictly controlled. The same is true in quenching process, and the heating time should be strictly controlled to avoid decarbonization. After the selection of data, the heat treatment is carried out, and the production is completed. After a certain number of attention to stress removal, there is reasonable planning, as far as possible to avoid stress convergence, pay attention to the R angle control. When about 10,000 modes are used, attention should be paid to the stress relief by tempering. The residual stress in the process of internal force convergence processing is not removed. The thermal stress in the process of die casting is not removed well, which is the embodiment of stress convergence. It is possible to select repeated tempering to remove stress and then to add the life of the die.

The main reasons for cracking of aluminium alloy die casting die after a period of production are as follows:

1. The die temperature is too high and the stress is too high.

2. Mould Benevolence Material 8407, Skd61

3. Excessive Hardness of Die Heat Treatment

4. Timing maintenance, 5K times1 tempering, 15K times1 tempering 30K times.

Die-casting die cracking is quite terrible, which ghosts are doing it!

To avoid the cracking of die casting die and improve the service life of die casting die, the following points should be done well:

1. Heat treatment of die casting parts (movable, fixed and core) requires hardness to be ensured at HRC 43-48 (SKD61 or 8407 is optional for data).

2. Mould should be preheated sufficiently before die casting production. The effect is as follows:

2.1 The heat balance of the die is better, the condensation speed of the castings is uniform and the pressure transfer is advantageous.

2.2 Adhering to the fluidity of die casting alloy filling, it has good formability and improves the surface quality of castings.

2.3 Cut down the bad production in the early stage and improve the production rate of die casting.

2.4 Decrease the thermal alternating stress of the die and improve the service life of the die.

Detailed criteria are as follows:

3. The accumulation of thermal stress is the direct cause of cracking of the die after a certain period of production. In order to reduce the thermal stress, the die and slider should be tempered to eliminate the thermal stress after a certain period of production.

Detailed requirements for eliminating thermal stress are as follows:

Aluminum alloy die casting die receives tremendous alternating working stress. It is necessary to pay attention to all aspects of die material, planning, processing, heat treatment and operation to get long die life. The following are the 22 key points for making die long life.

1. High Quality Die Material

2. Rational Planning of Die Wall Thickness and Other Die Sizes

3. Choose inserts as far as possible

4. Choose the largest turning angle R under possible conditions

5. It is necessary that the distance between the cooling channel and the profile and the corner be large enough.

6. Stress Removal and Tempering after Rough Machining

7. With proper heat treatment, quenching and cooling should be fast enough.

8. Removal of EDM metamorphic layer by thorough polishing

9. Shape surface should not be highly polished

10. Mould surface should be oxidized

11. If nitriding is selected, the nitriding layer should not be too deep.

12. Preheat the mould to the recommended temperature in the correct way

13. Slow hammer speed should be used for 5-10 pieces of die casting at the beginning

14. Decrease the temperature of molten aluminium as far as possible on the premise of obtaining qualified products

15. Do not use too high injection speed of liquid aluminium

16. To ensure proper cooling of the die, the temperature of the cooling water should be maintained at 40-50 C.

17. For temporary shutdown, the mould should be closed as far as possible and the cooling water quantity should be reduced to avoid the thermal shock of the mould when the machine is restarted.

18. Turn off the coolant when the model surface is at the highest temperature

19. Not too much spray release agent

20. Destressing and tempering after a certain amount of die casting

1. The main reason is that the temperature is too high. It is advocated that the temperature should be controlled at any time in the process of die casting by using thermometers (the advocated temperature for aluminium alloy die casting is < 650).

2. Pay attention to the preheating of the mould to avoid thermal exhaustion. (Cracks are mainly caused by heat exhaustion)

3. Pay attention to die processing. It is better to finish with a machining center. If there is a need for electro-processing, grinding and polishing processes should be added after electro-processing.

4. Pay attention to the maintenance of dies (de-stress tempering)

5. The ASSAB 8407 data should be selected for the die with high life, and the hardness of die casting die should not be higher than 50HRC.