The control of surface temperature of die casting mould is very important for high quality die casting. Not average or improper casting mold temperature will also lead to unstable casting size, ejection in the process of production of casting deformation, thermal pressure, sticky mold, surface depression and shrinkage cavity and defects such as hot bubble. When the temperature difference is large, the variables in the production cycle, such as filling time, cooling time and spraying time, have different degrees of influence. The following is a list of common die casting mold improvement methods.
To improve the method
The temperature in the front end of the molten soup is too low to be overlapped.
1. Check whether the wall thickness is too thin (design or manufacture), and the thinner area should be filled directly.
2. Check whether the shape is not easy to fill; The distance is too far away, the enclosed area (such as fin (fin), convex), blocked area, round corner is not easy to fill. And notice whether there are ribs or cold spots.
3. Shorten the filling time. Method to shorten the filling time.
4. Change the fill pattern.
5. Improve the mode temperature.
6. Increase the temperature of the molten soup.
7. Check alloy composition
8. Greater escape routes may be useful.
9. A vacuum device may be useful.
1. Shrinkage stress
2. The force is cracked at the top or the whole edge.
1. More rounded corners
2. Check for hot spots.
3. Pressurization time change (cold chamber machine)
4. Increase or shorten the closing time.
5. Increase drawing Angle
6. Top out pin
7. Check whether the mold is dislocated and deformed.
8. Check alloy composition
1. The air was mixed with molten soup.
2. Source of gas: when melting, in the material tube, in the mold, the parting agent.
1. Moderate speed
2. Check whether the turn is smooth and the area is decreasing.
3. Check if the area of escape is large enough, whether there is a blockage, and whether the locations is located at the last filling place.
4. Check whether there is too much spray and the mold temperature is too low.
5. Use the vacuum
Due to the sudden decrease of pressure, the gas in the molten soup suddenly expands, impacting the mold and causing the mold damage.
Do not change the area of the passage rapidly.
When the metal is solidified into a solid state, the space occupies less space. If no metal is added, it will form a shrinkage cavity. It usually occurs at a slower setting.
1. Increase the pressure
2. Change the mold temperature. Local cooling, spray separation agent, reduce mold temperature. Sometimes it just changes the position of the hole, not the shrinkage cavity.
1. The filling mode is bad and the fusion soup is overlapped.
2. Mold deformation, resulting in fusion soup overlapping.
3. Inclusion oxide layer
1. Switch to high speed early.
2. Short fill time
3. Change the filling mode, gate position and gate speed.
4. Check whether the mold strength is sufficient.
5. Check whether the pin dies are good.
6. Check for inclusion of oxide layers.
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 it has enough fusion to make the organization different.
1. Improved filling mode
2. Short fill time
A hole produced by a malfunctioning flow.
The molten soup is too slow, too cold, or poorly filled, so there is a hole in the solidified metal joint.
1. Same as improving the cold pattern.
2. Check whether the temperature is stable.
3. Check whether the mold temperature charge is stable.
The hole in the parting surface.
It could be shrinkage or porosity.
1. If shrinkage cavity, reduce gate thickness or overflow well inlet thickness.
2. Cooling gate
3. If the stomata, pay attention to the problem of exhaust or volume.
1. Lack of clamping force
2. Poor mold closing.
3. Insufficient mold strength
4. The molten soup is too hot.
The shrinkage cavity occurs under the surface of the pressing piece.
1. Methods for improving shrinkage cavity.
2. Local cooling
3. Heat the other side
The parting agent or other impurity product is attached to the mold
1. Reduce the spray amount of the parting agent.
2. Higher mold temperatures
3. Choose the appropriate parting agent.
4. Use soft water to dilute the parting agent.
The gas is rolled under the surface of the casting.
1. Reduce the volume of air (air holes)
2. Cool or low mold temperature.
1. Zinc is deposited on the surface of the mold.
2. Molten soup impact mold, causing surface damage.
1. Lower mold temperature
2. Reduce the surface roughness.
3. Enlarged drawing Angle
5. Change fill mode
6. Lower gate speed.