Solving common problems of die casting molds


The so-called die-casting mold process is to organically and comprehensively use these three elements to enable stable, rhythmic and efficient production of qualified castings with good appearance, internal quality, and dimensions that meet the requirements of the drawing or agreement, and even high-quality die-casting process. Die-casting mold materials, die-casting mold design, and die-casting machine are the three major elements of die-casting production, and none of them are indispensable.

The control of the surface temperature of the die-casting mold is very important for the production of high-quality die-casting parts. Uneven or inappropriate die-casting mold temperature will also cause the size of the casting to be unstable, and the casting will be deformed during the production process, resulting in defects such as thermal pressure, mold sticking, surface depression, internal shrinkage and hot bubbles. When the mold temperature difference is large, the variables in the production cycle, such as filling time, cooling time, and spraying time, will be affected to varying degrees. common problem:

1). Cold pattern:

Reason: The temperature at the front end of the die-casting mold material is too low, and there are traces when they overlap.

Improve methods:

1. Check whether the wall thickness is too thin (designed or manufactured). The thinner area should be directly filled.

2. Check whether the shape is not easy to fill; too far, closed areas (such as fins, bumps), blocked areas, too small rounded corners, etc. are not easy to fill. And pay attention to whether there are ribs or cold spots.

3. Shorten the filling time. Ways to shorten the filling time:...

4. Change the filling mode.

5. Ways to increase mold temperature:...

6. Increase the melting temperature of die casting mold materials.

7. Check the alloy composition.

8. Enlarging the escape airway may be useful.

9. Adding a vacuum device may be useful.

2). crack:

Reasons: 1. Shrinkage stress.

2. Forced to crack when ejected or the whole edge.

way of improvement:

1. Increase the fillet.

2. Check for hot spots.

3. Change of boost time (cold room machine).

4. Increase or shorten the clamping time.

5. Increase the draft angle.

6. Increase ejector pins.

7. Check whether the mold is misaligned or deformed.

8. Check the alloy composition.

3). Stoma:

Reasons: 1. Air is mixed in the molten soup.

2. The source of the gas: during melting, in the barrel, in the mold, and release agent.

Improve methods:

1. Appropriate slow speed.

2. Check whether the runner turns smoothly and whether the cross-sectional area is gradually decreasing.

3. Check whether the area of the escape airway is large enough, whether it is blocked, and whether the location is in the last filling place.

4. Check if the release agent is sprayed too much and the mold temperature is too low.

5. Use vacuum.

4). Cavitation:

Reason: Due to the sudden decrease in pressure, the gas in the molten soup suddenly expands and impacts the mold, causing mold damage.

Improve methods:

The cross-sectional area of the runner should not change rapidly.

5). Shrinkage:

Reason: When the metal solidifies from a liquid state to a solid state, the space occupied becomes smaller. If there is no metal supplement, shrinkage cavities will be formed. Usually occurs at a slower solidification.

Improve methods:

1. Increase pressure.

2. Change the mold temperature. Local cooling, spray release agent, lower mold temperature,. Sometimes just change the position of shrinkage hole, not shrinkage hole.

6). ripple:

Reason: The first layer of molten soup cooled rapidly on the surface, and the second layer of molten soup failed to melt the first layer, but there was enough fusion, resulting in a different organization.

Improve methods:

1. Improve the filling mode.

2. Shorten the filling time.

7). Holes caused by poor flow:

Reason: The molten stock flows too slowly, or is too cold, or the filling mode is bad, so there are holes in the solidified metal joints.

Improve methods:

1. The same method to improve cold lines.

2. Check whether the molten soup temperature is stable.

3. Check whether the mold temperature charge is stable.