Secondly: Precautions for the mold during the production process~ When it comes to mold maintenance and maintenance, a concept will immediately flash in the minds of many die-casting operators. They always think that it is a mold repair work, which has little to do with him. In fact, the opposite is true. The fate of all molds can be said to be in the hands of die-casting operators. For example, you have a car that broke down after several years of driving. Can you say that it was caused by those car washings? So the following points should be paid special attention to during the use of the mold:
(1) The use of mold cooling system. When the mold cooling water is used correctly, it not only prolongs the service life of the mold, but also improves the production efficiency. In actual production, we often neglect its importance. The operators also try to save trouble. If it is too troublesome to connect and connect, we don’t need to connect the cooling water pipe. Some companies even do not cool down in order to save costs when customizing the mold. Water, which caused very serious consequences. The material of the mold is generally made of special mold steel through various treatments, and even the best mold steels have their limits of use, such as temperature. When the mold is in use, if the mold temperature is too high, it is easy to cause tortoise cracks on the surface of the mold core early. In some molds, tortoise cracks appear on a large scale even before more than 2000 times. Even during the production of the mold, the color of the mold core has changed due to the high mold temperature, and even reached more than 400 degrees after measurement. This temperature is prone to cracks when the mold release agent is chilled. The produced product It is also prone to deformation, strain, and mold sticking. In the case of using mold cooling water, the use of release agent can be greatly reduced, so that the operator will not use the release agent to lower the temperature of the mold. The advantage is to effectively extend the life of the mold, save the die-casting cycle, improve the quality of the product, reduce the occurrence of mold sticking, strain and aluminum sticking, and reduce the use of mold release agents. It can also reduce the loss of ejector pins and cores caused by overheating of the mold.
(2) The mold must be preheated during the start of production to prevent the occurrence of turtle cracks when the cold mold suddenly encounters hot molten metal. The more complex mold can use blowtorch, liquefied gas, and the conditions are good. With a mold temperature machine, relatively simple molds can be preheated by slow injection.
(3) The cleaning of the mold parting surface is very troublesome and easy to overlook. If the boss has a high starting point and buys a good mold, then the work will be much easier. If the quality of the mold is not good, It is inevitable that there will be flash or dirt on the parting surface of the mold during production. The operator should clean these parts frequently and be equipped with a small spatula at any time (the company should provide your employees with tools and good guns. To fight). If the flash is not removed in time, the parting surface of the mold is easy to collapse, causing aluminum to run out during the production process. Once this result is caused, no matter how good a mold repair expert you are, the possibility of a complete repair is very small. Yes, it’s not that they don’t have the skills. The consequences of running aluminum will not only increase the cost of die casting, waste aluminum, and product quality is also unstable, especially the internal quality, but also increase the difficulty of determining process parameters, and the pass rate will drop a lot. From safety considerations, Increased the chance of a work injury. During the handover, the operator should thoroughly clean the parting surface of the mold with kerosene, which can not only prevent the mold from being crushed, but also after cleaning, it can drain the mold from the mold release agent residue or other dirt. The opening of the gas groove is beneficial to the discharge of the gas in the cavity during the injection process to improve the product quality. It is advisable for a team to clean the parting surface twice. Let employees develop a good habit.
(4) If the mold is equipped with neutron control, please pay attention to absolutely prohibit the signal line between the die casting machine and the mold from having joints. The reason is clear. In daily production, it is difficult to avoid water on the signal line or the joints. The place is easy to break, resulting in short-circuit with the machine tool. If there is a signal error, the alarm will automatically stop and delay the time, and the signal will be disordered and the mold will be damaged. Cause unnecessary losses. Pay attention to the waterproof of the travel switch.
(5) When each team takes over, check carefully according to the “Mold Inspection Table” of our company, and solve the problems in time to avoid unnecessary troubles to themselves.
Furthermore: the responsibilities of the mold repair class play the role of “treating diseases and strengthening the body without diseases” in the maintenance and maintenance of molds. For a set of molds, a batch of tasks are completed. After the mold is removed, the mold repair personnel must Have a very detailed understanding of this set of molds, such as how many molds have been produced so far, what failures have occurred, check the tail product to understand the current mold status, whether it has reached the safe service life of the mold, and whether it should be based on production The quantity should be reported to the workshop for mold preparation, etc.~ It is necessary to check the file of this mold;
(1) Mold repair personnel must master a principle in the process of maintenance, repair and maintenance. It is absolutely not allowed to change the size of the mold without permission. Work under such a premise. Once the original size is changed, there will be batch quality. In the event of an accident, the loss will be very heavy.
(2) Carry out maintenance work effectively in accordance with the “Regulations on the Management of Mold Repair and Maintenance” of the company. In the maintenance process, the mold repairers lack the use awareness of the tools used. For example, in the process of polishing the mold, they use relatively coarse oil stone, and some even install the polishing machine on the louver wheel to polish the mold core, which not only causes the mold core. There are deep scratches everywhere on the surface, and the nitride layer on the surface of the mold core is damaged, making the die-casting impossible to use in the next production. It is either sticking or straining. There are many situations like this. The last time the mold was produced well, it would be impossible to work after this re-production. In addition to other external factors, this is a very important reason.
(3) For vulnerable parts such as ejector pins, cores, etc. should be carefully checked for bends, cracks, etc., if they are replaced in time, in many cases the cores will be broken after the mold is reproduced without completing many molds, most of the reasons As a result, there is no careful inspection, and problems are not discovered in advance, resulting in a great waste of manpower and time.
(5) Polishing the mold needs to add one point, wherever there is sticky aluminum, wherever there is carbon deposits, polish it, so as to minimize the wear and tear on the mold caused by polishing.
(6) All moving parts of the mold, joint parts, screws, etc. should be lubricated and anti-rust treated.
(7) The mold management personnel monitor the maintenance status at any time and pay attention to other management details. Make maintenance records for inquiries.
The storage of the mold should be consistent with the ledger, drawings, files, etc. The mold cannot be disassembled and stored to avoid the loss of parts, and the molds that are not used for a long time should be treated with rust regularly. The new mold should be treated with stress relief as much as possible within the specified period to extend its service life.
In the process of mold maintenance and repair, some things are quite simple and understandable, but it is really difficult to do it. It requires us to implement it diligently and make the work in place.
Three, in the process of die-casting production
1. Mold temperature The mold should be preheated to a certain temperature before production. Otherwise, chilling will occur when the high temperature molten metal is filled, which will cause the temperature gradient of the inner and outer layers of the mold to increase, forming thermal stress, and cracking or even cracking on the mold surface. In the production process, the mold temperature continues to rise. When the mold temperature is overheated, it is easy to stick to the mold, and the moving parts fail to cause damage to the mold surface. A cooling temperature control system should be set up to keep the mold working temperature within a certain range.
2. Filling metal liquid with high pressure and high speed filling will inevitably produce intense impact and erosion on the mold, which will cause mechanical and thermal stress. In the impact process, molten metal, impurities, and gas will also produce complex chemical interactions with the surface of the mold, and accelerate the generation of corrosion and cracks. When the molten metal is surrounded by gas, it will expand first in the low pressure area in the cavity. When the gas pressure increases, inward blasting will occur, pulling out the metal particles on the surface of the cavity to cause damage, and cracks due to cavitation.
3. Production process In the production process of each die-casting part, due to the heat exchange between the mold and the molten metal, the surface of the mold produces periodic temperature changes, causing periodic thermal expansion and contraction, and generating periodic thermal stress. For example, the surface of the mold is subjected to compressive stress due to the heating during pouring, and after the mold is opened to eject the casting, the surface of the mold is subjected to tensile stress due to the cooling. When this alternating stress is repeatedly cycled, the stress accumulated inside the mold becomes larger and larger. When the stress exceeds the fatigue limit of the material, cracks occur on the surface of the mold.