1). Cold pattern:
Cause: The temperature at the front end of the melt is too low, and there are marks when stacked.
Improving 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; the distance is too far, the closed area (such as fins, bumps), the blocked area and the fillet are too small, est., all of which are not easy to fill. And pay attention to whether there are ribs or cold spots.
3. Shorten the filling time.
4. Change the filling method.
5. Increase 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). crack:
Reason:

1. Contraction stress.
2. Forced to split when eject or round edge.
Improving methods:
1. Increase the fillet.
2. Check for hot spots.
3. Change the pressurization time (cold chamber machine).
4. Increase or shorten the clamping time.
5. Increase the draft angle.
6. Increase the ejector pins.
7. Check if the mold is misaligned and deformed.
8. Check the alloy composition.

3). Porosity:
Reason:

1. The air is mixed in the melt.
2. Source of gas: during melting, in the tube, in the mold, in the release agent.
Improving methods:
a. Proper slower speed.
b. Check if the flow path is smooth and the cross-sectional area is decreasing.
c. Check if the air vent is large enough, whether it is blocked, and whether the location is at the last filling place.
d. Check if the release agent is sprayed too much and the mold temperature is too low.
e. Use vacuum.

4). Cavitation:
Reason: Due to the sudden decrease in pressure, the gas in the melt suddenly expands to impact the mold, causing damage to the mold.
Improving method:
The cross-sectional area of the flow channel should not be changed rapidly.

5). shrinkage:
Reason: When the metal solidifies from the liquid to the solid state, the occupied space becomes smaller. If there is no metal supplement, the shrinkage cavity will be formed. Usually occurs at slower solidification.
Improving methods:
1. Increase the pressure. 2. Change the mold temperature. Cool partially, spray release agent, lower mold temperature. Sometimes change the position of the shrinkage hole.

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