The mold determines the shape and quality of the casting, which is mainly used to make aluminum die castings. Before the large-scale production, aluminum die casting factory usually carry out on-machine tests on newly developed molds, trial produce a small number of aluminum alloy castings, and test and inspect them to verify the feasibility of the production process and the qualification of the casting quality.
The development of new products and the renewal of old molds are often encountered in die casting production. The main purpose of the mold test is to find out the optimal process parameters and mold modification program, requiring that even if the material, machine Settings or environmental factors have changed, it can still ensure that the mold can be stable and uninterrupted mass production of qualified products, to maximize the “adaptability” of the mold.
In order to avoid casting defects caused by molds, minimize errors in the production process, improve production efficiency and reduce costs, and help find possible problems in production and solve them in time, it is necessary to test the completed molds.
1．Find out the mold problems
Due to poor design or the imprecise processing in the production process, there are some problems happen, such as out-of-size, local transition is not smooth, inappropriate structure, etc., resulting in unqualified castings or mold trial production can’t be carried out. And mold testing is the most simple, direct and effective way to find mold problems.
2．Find out the best forming conditions
In the process of mold testing, worker can find a group of the most suitable process data, and this group of data can be used in mass production, as the default value of setting machine parameters, according to the set of data to adjust the best process conditions for mold mass production. It is also necessary to strictly control the composition of raw materials and the temperature, time and other parameters during the melting process.
3．List the reasonable mold testing procedures
One of the purposes of mold testing is to determine reasonable mold testing steps and make appropriate records for the future formal production is of great significance.
4．Check the mold
According to the mold’s drawing, we should check for the relevant dimensions. Make clear the action sequence of each moving part of the mold in detail. Confirm that the die casting machine model, injection position, tubing interface, pressure chamber diameter and interface size to be used are consistent with the actual requirements of the mold. Specially, it should be noticed that the testing die casting machine must be consistent with the die casting machine model which used in the mass production, otherwise, it may lead to the mold cannot be used.
Die casting mold installation should be ensured that the pressure center and the machine center as much as possible to avoid deviation or adverse effects in the production.
In addition, pay attention to the heating and cooling of the mold to avoid casting deformation or defects caused by temperature changes.
5．Check the first die casting, and then adjust the process parameters
After making the first die casting in the test mold, the following checks should be carried out:
① Thickness of leftover cake;
② supercharging specific pressure;
③ mold filling speed;
④ casting ejection length;
⑤ Quality of castings, gates and slag bags.
The purpose of the above inspection is to prevent the finished product from shrinking, flash, mucous membrane and even damage to the mold. According to the inspection results, the process parameters are further adjusted to achieve the best die casting process conditions.
6．On – site inspection of sample
With the stable process parameters, the test die-castings after the mold testing need for technical personnel according to the requirements of customers on-site inspection, the main inspection contents are:
① Measure the machining allowance of the main parts
② Check the burr and flash distribution of castings, especially those with sliders. Although the running water at the parting surface of the sliders has little impact on the size of the product, it will bring serious accident risks to the subsequent mold production, such as the sliders stuck and the inclined guide column broken.
③ Cut the casting to check the internal pores, shrinkage holes, etc.
④ Observe if the casting appearance is strained, teared, etc.
On-site can intuitively judge the mold problem, as far as possible to provide customers with a good test casting. According to the situation of the site, the workers give suggestions for the subsequent mold repair. The detailed inspection of the test die casting needs to be did the full inspection and the trial machining of the casting by the inspector.
The mold test is a practical inspection process of the use of the mold. The samples, inspection records and process parameter records (including various pressures, pouring temperatures and mold temperatures & time, etc.) should be properly kept during the mold test. To solve various problems in the test mold is a patient and careful work, we should have a detailed understanding of the casting structure, die casting process, mold structure. To prevent causing unnecessary losses, it’s not sensible to modify the mold blindly.
Finally, it should be emphasized that the purpose and focus of mold testing is to optimize the mold and process to meet the requirements of mass production.