Crack

Update:02-11-2018
Summary:

2). crack: the reason: 1. Contraction stress 2. Forced […]

2). crack:
the reason:
1. Contraction stress
2. Forced to split when ejector or full edge
way of improvement:
1. Increase the fillet
2. Check for hot spots
3. Boost time change (cold chamber machine)
4. Increase or decrease the clamping time
5. Increase draft angle
6. Increase the ejector pin
7. Check if the mold is misaligned and deformed
8. Check alloy composition
3). Stomata:
the reason:
1. Air inclusions in the melt
2. Source of gas: during melting, in the tube, in the mold, release agent
Improve methods:
1. Proper 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. Using vacuum
4). Cavitation:
Cause: The gas suddenly melted in the melt, causing the gas in the melt to suddenly expand, causing the mold to be damaged.
Improve methods:
Do not change the cross-sectional area of ​​the flow channel
5). shrinkage cavity:
Reason: When the metal solidifies from a liquid to a solid, the space occupied becomes smaller. If there is no metal replenishment, a shrinkage cavity will be formed, which usually occurs at a slower solidification.
Improve methods:
1. Increase pressure
2. Change the mold temperature. Local cooling, spray-off agent, lower mold temperature, Sometimes just changing the shrinkage hole position, not the shrink hole
6). Peeling:
the reason:
1. Poor filling mode, causing melt overlap
2. The mold is deformed, causing the soup to overlap
3. Inclusion oxide layer
Improve methods:
1. Switch to high speed early
2. Shorten filling time
3. Change fill 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 failure to melt the first layer, but there is enough fusion to cause different tissues.
Improve methods:
1. Improve filling mode
2. Shorten filling time
8). Holes resulting from 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 melt temperature is stable
3. Check if the mold temperature charge is stable

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