During each die casting, it is necessary to clean the die casting mold and spray release agent, so that it can continuously produce and obtain zinc alloy die castings with consistent requirements. In this guide, we discuss how can reasonable use of release agent extend the life of die casting mold.
1. Clean the parting surface first
Blow off the residue left on the die with an air spray gun. The residue on the parting surface will affect the die casting mold, cause the produced zinc alloy die casting to produce flash, damage the parting surface of the die casting mold and damage the die. If it is not found in time, the flash will be aggravated in light cases and the zinc alloy die casting will be deformed in heavy cases.
At will, it is best to equip the air gun in the production, and leave a special circuit when designing the die-casting mold. In particular, during the die test, pay attention to observe the position of the residue, and adjust the blowing position and angle to ensure that the residue can be completely cleaned.
2. Spray release agent
Spraying release agent can form isolation film on the surface of die casting mold, avoid the scouring of liquid metal on the die surface during injection molding, improve the degree of filling flow, prevent mucous membrane, reduce strain, improve the surface quality of zinc alloy die-casting parts and improve the service life of the mold.
3. Reasonable proportion and use of coatings
The dilution ratio of the coating has a certain range of requirements. The concentration is too low and the film is too thin to resist the scouring of thermal stress of liquid metal, resulting in mucous membrane damage. If the concentration is too high and the film is too thick, the surface finish of the casting will be affected, and the coating in the cavity will accumulate and enter the liquid metal, resulting in gas generation. The dilution ratio of coating is an important process parameter, and the dilution ratio of large parts, thin walls, complex parts and complex parts should be lower. The dilution ratio of small and simple parts should be higher. The most suitable dilution ratio and spray amount can be determined through trial.
In order to ensure that a uniform film is formed on the mold surface, the coating should be atomized. In this way, the coating should be evenly dispersed and have strong adhesion. The atomization should be fine mist. A good atomized coating can stay on the cavity surface more effectively. A suitable injection device shall be provided and a suitable configuration shall be used.
If the spraying distance is too small and the flow rate is too high, the release agent will rebound and cause loss. However, if the distance is too large, the fog coating will fuse into large droplets. The ideal spraying distance is 100 ~ 200 mm. The spraying time of 1 ~ 2S is enough to form a sufficiently thick isolation film. The shape of the mold is complex, so it is necessary to pay attention to the places that cannot be sprayed, and also pay attention to controlling the spraying angle.
4. Position requirements for spraying release agent
The coating points are very important. After the test, the reasonable points shall be recorded for reuse, so as to obtain the stability of product quality. It should be noted that after a certain time of mold test and production, the mold temperature will change due to the fixation of heat transfer and cooling. At this time, the spraying point should be confirmed again. In addition to spraying the casting position, the spraying point should also remind that the slag ladle and exhaust position should be sprayed. The long-term impact of molten aluminum will increase the temperature of this part and produce flying materials or sticking molds. These abnormal events, It will cause damage to the parting surface of the die-casting mold, which are often ignored, especially when testing the die.
5. Balance die temperature
Water spray can cool the mold and indirectly balance the mold temperature, which is a fine and explorable work. Die casting mold temperature has a great influence on zinc alloy die castings. Surface finish, soup back, die sticking, size variation, etc. are all related to it. However, the position and temperature control shall be different due to the condition of each pair of molds. These parameters and experience must finally be obtained on site. The obtained parameters must also be tested by the time of temperature change. If not, there will be good mold test, but new problems will appear after production. The mold temperature gradient is different at the beginning and after a long time.
At present, the spraying time mostly depends on the cooling of the mold. Therefore, the temperature detection of the die is very important. The mold temperature is different in the process of mold trial, initial production and stable production. After the mold temperature is detected, part of the too low temperature will be unfavorable to the casting. Adjust the spraying position if necessary. For high temperature, multi pipe and large flow spraying can be used to shorten the time.