Is die casting mold directly related to product quality?
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 temperatures can also lead to unstable casting dimensions, which can cause deformation of the casting during the production process, resulting in defects such as heat pressure, sticking, surface depression, shrinkage cavities and thermal bubbles. When the difference in mold temperature is large, the variables in the production cycle, such as filling time, cooling time and spraying time, have different effects.
1). Cold pattern:
Reason: The temperature at the front end of the melt is too low, and there are traces when stacked.
Improve methods:
1. Check if the wall thickness is too thin (design or manufacture), and the thinner area should be filled directly.
2. Check if the shape is not easy to fill; too far, closed areas (such as fins, bumps), blocked areas, rounded corners, etc. are not easy to fill. Also pay attention to whether there are ribs or cold spots.
3. Shorten the filling time.
4. Change the filling mode.
5. Improve the mold temperature.
6. Increase the temperature of the melt.
7. Check the alloy composition.
8. It may be useful to increase the escape route.
9. Adding a vacuum device may be useful.
2). Cracks:
the reason:
1. Shrinkage stress.
2. Forced to split when ejecting or trimming.
way of improvement:
1. Increase the fillet.
2. Check if there is a hot spot.
3. The pressurization time changes (cold room machine).
4. Increase or shorten the clamping time.
5. Increase the draft angle.
6. Increase the ejector pin.
7. Check if the mold is misaligned and deformed.
8. Check the alloy composition.
3). Pores:
the reason:
1. The air is mixed in the melt.
2. Source of gas: during melting, in the material tube, in the mold, release agent.
Improve methods:
1. Appropriate slow speed.
2. Check if the flow path is smooth and the cross-sectional area is decreasing.
3. Check if the area of the escape route is large enough, whether it is blocked, and whether the location is at 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 melt suddenly expands, impacting the mold, causing damage to the mold.
Improve methods:
The cross-sectional area of the flow channel should not be changed rapidly.
5). Shrinkage:
Reason: When the metal solidifies from a liquid to a solid, the space occupied becomes smaller. If there is no metal supplement, a shrinkage cavity will be formed. Usually occurs at a slower solidification.
Improve methods:
1. Increase the pressure.
2. Change the mold temperature. Local cooling, spray off the mold, reduce the mold temperature, sometimes just change the shrinkage hole position, not the shrinkage hole.
6). Peeling:
the reason:
1. Poor filling mode, causing the soup to overlap.
2. The mold is deformed, causing the melt to overlap.
3. Inclusion of oxide layer.
Improve methods:
1. Switch to high speed early.
2. Shorten the filling time.
3. Change the filling mode, gate position, gate speed.
4. Check if the mold strength is sufficient.
5. Check if the pin die is good.
6. Check for inclusion of oxide layer.
7). Ripple:
Reason: The first layer of molten soup is rapidly cooled on the surface, and the second layer of molten soup flows through the first layer without melting, but there is enough fusion to cause different tissues.
Improve methods:
1. Improve the filling mode.
2. Shorten the filling time.
8). Holes produced by poor flow:
Cause: The melt flow is too slow, too cold, or the filling mode is poor, so there is a hole in the solidified metal joint.
Improve methods:
1. Same as improving the cold grain method.
2. Check if the temperature of the melt is stable.
3. Check if the mold temperature charge is stable.
9). Holes in the parting surface:
Cause: It may be a shrinkage hole or a pore.
Improve methods:
1. If it is a shrinkage hole, reduce the thickness of the gate or the thickness of the inlet of the overflow well.
2. Cool the gate.
3. If it is a vent, pay attention to the problem of exhaust or gas.
10). Raw edges:
the reason:
1. The clamping force is insufficient.
2. The mold is not properly clamped.
3. The mold strength is insufficient.
4. The temperature of the melt is too high.
11). Constriction:
Cause: The shrinkage hole occurs below the surface of the presser.
Improve methods:
1. The same method to improve shrinkage.
2. Local cooling.
3. Heat the other side.
12). Carbon deposit:
Cause: Release agent or other impurities are attached to the mold.
Improve methods:
1. Reduce the amount of release agent spray.
2. Increase the mold temperature.
3. Choose a suitable release agent.
4. Dilute the release agent with soft water.
13). Bubbling:
Cause: The gas is rolled under the surface of the casting.
way of improvement:
1. Reduce the volume of gas (same pores).
2. Cool or prevent low mold temperature.
14). Sticky mold:
the reason:
1. Zinc is deposited on the surface of the mold.
2. The molten soup impacts the mold, causing damage to the mold surface.
Improve methods:
1. Reduce the mold temperature.
2. Reduce the roughness of the surface.
3. Increase the draft angle.
4. Coating.
5. Change the filling mode.
6. Reduce the gate speed.
