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Cause Analysis And Preventive Measures Of Aluminum Alloy Mould Cracking Easily
Sep 18, 2018

After a period of production, the mold of die casting for aluminum alloy mold will crack. After analysis, the reasons for this phenomenon are as follows:
(1) excessive stress on the high temperature of the mold
(2) mold material: 8407,skd61
(3) excessive hardness of mold heat treatment
(4) regular maintenance, 5k times1 tempering, 15k times1 tempering 30k times......
Preventing the cracking problem of die casting die, raising the service life of imported die steel
1. Pressure casting mold forming part (movable mold and mold core) required for heat treatment; hardness must be guaranteed between HRC43 and 48 (SKD61 or 8407 can be selected as the material)
2. The mold should be fully preheated before die-casting production, and its functions are as follows
2.1 make the mold reach a good thermal balance to make the casting solidification rate uniform and facilitate pressure transfer.
2.2 maintaining the fluidity of die-casting alloy filling has good formability and improving the casting surface quality.
2.3 reduce early production defects and improve die-casting productivity.
The specific specifications are listed below
Alloy type aluminum alloy zinc alloy
Die preheating temperature (180 ~ 300 ℃) from 150 to 200

3. The heat stress accumulation of new molds after a certain period of production is the direct cause of mold kernels cracking, while the heat stress reduction should be performed on mold kernels and slide blocks after a certain period of production
The production modes required to eliminate thermal stress are as follows
Mold type first tempering second tempering third tempering
Aluminum alloy <2000 mode <10000 mode <30000 mode
Zinc alloy <10000 mould <20000 mould <50000 mould

3. 20-point tips for long life of the mold:
1. High quality moulds
2. Reasonably design mold wall thickness and other mold dimensions
3. Try to use the bottom page of insert. 4
5. The distance between the cooling channel and the profile and rotation Angle must be large enough
6. Stress tempering should be removed after rough machining
7. Heat treatment is correct, and quenching and cooling must be fast enough
8. Thoroughly polish and remove the EDM catamite layer
9. The profile cannot be highly polished
10. The mold surface shall be oxidized
11. If nitriding is selected, the infiltration layer should not be too deep
12. Preheat the mold to the recommended temperature in the correct way
13. Starting 5 ~ 10 pieces of die-casting shall use slow head speed
14. Reduce aluminum liquid temperature as far as possible on the premise of obtaining qualified products
15. Do not use too high injection speed of aluminum liquid
16, ensure mold properly cooling, cooling water temperature should be kept in 40 ~ 50 ℃
17. For temporary stopping, the mold should be closed and the cooling water should be reduced as much as possible to avoid thermal shock on the mold when restarting
18. The cooling fluid should be closed when the model surface is at the highest temperature
19. No more than a few sprays
20. De-stress tempering after a certain amount of die casting