Hardware Fitting -Internal Quality Control Of Die Casting


Die casting, also known as high pressure casting, is a near net shape technology that has been widely used in the automotive, aerospace and electronics industries in recent years

.

 

Die casting, also known as high pressure casting, is a near net shape technology that has been widely used in the automotive, aerospace and electronics industries in recent years. In the die-casting process, molten metal (usually a light alloy) fills the cavity at high pressure and high speed under the action of a punch, and cools rapidly to form the final casting.

Die casting is usually divided into cold chamber die casting and hot chamber die casting. Cold chamber die castings are mainly used in the production of large parts, such as automotive parts and cooling parts for communication base stations. Hot chamber die casting is widely used in the production of small electronic or 3C products. Process, such as USB connector, notebook case, etc.

1. Die casting has a good foundation for automation

Compared with ordinary casting process, die casting has the characteristics of high speed and high pressure. The products produced are usually light alloy thin-walled parts, but die-casting technology is also used to produce pure copper rotors. Unlike aluminum and magnesium alloys, pure copper has a very high melting point, so short die life in the pure copper die casting process is a big problem.

Among all casting technologies, die casting has the highest degree of automation. Modern die-casting companies use automated die-casting island technology, which is highly integrated with die-casting machines (usually dozens or even hundreds) to form a fully automated production process. At the same time, the intelligent factory technology is used to monitor the production process of the die-casting machine, grasp the performance and status of each die-casting machine in real time, and adjust the production process big data measurement and real-time feedback of the die-casting machine in the following ways to ensure the quality of the final product .

The real-time control of die casting mold temperature is a simple example:

Take cold chamber die casting as an example. During the production process, the mold temperature continues to rise due to the continuous filling of the mold cavity with high temperature liquid metal. At this time, in order to ensure that the temperature of the mold does not overheat, cooling water is usually used to cool the mold. Generally, if the design of the cooling water pipeline is reasonable, the temperature and flow of the cooling water can be controlled to ensure that the temperature of the mold reaches the so-called thermal balance. From this perspective, we can design a cooling water feedback system. After knowing the actual value of the mold temperature, the temperature and flow of the cooling water can be controlled through calculation and an instant feedback system, and finally the temperature of the mold can be controlled. This is a typical application for die casting in smart factories at this stage.

In fact, the above intelligent control situation is only a small application scenario in the "smart factory". In order to achieve a true "smart factory", a large amount of real-time production data needs to be collected, among which data related to product quality is decisive, such as density, porosity and oxidized inclusions, because these data are the things that index customers care most about, and also The core index to measure the qualification of castings. At this stage, these most critical indicators are the most difficult to obtain, because for metal alloy products, we cannot directly observe the internal structure of the product. Most manufacturers use spot checks to cut the castings into key areas clearly specified by the customer, and then directly observe whether there is a problem; another method is to use two-dimensional X-ray inspection technology to scan the local position of the casting and observe, this method The biggest problem is that the 3D casting information is compressed into 2D slices, and the results obtained by observing the information cannot fully reflect the actual situation.

 

2. Internal quality control of castings

With the continuous development of the automobile industry, the requirements for the quality of parts are getting higher and higher. Large automakers continue to formulate internal quality requirements for parts and components, and quantify the standards for possible internal defects in parts. In this case, component suppliers must be able to detect and calibrate the distribution of defects in all castings in real time during the production process, and compare standards to assess whether the castings meet the requirements.

So how to correctly observe and record the defects inside the casting? The best technology in the existing technology is computer tomography, also known as CT technology. CT technology has been widely used in the medical field, and the application of CT technology in industrial inspection is still an emerging technology in recent years.

To apply CT technology to the internal quality inspection of castings, the following requirements must be met:

First, the inspection speed must be high enough to match the real-time production process of castings.

Secondly, the quality of the image obtained through the inspection must be good enough to match the subsequent software's accurate image recognition;

Third, while ensuring accuracy, the software or algorithm that recognizes the image must be fast enough to avoid delaying the production schedule.

Among them, the first two requirements are the CT test itself, and the last requirement is the test software or algorithm. Looking at the existing CT technology, we will find that the most promising test instrument is the Quick-Test CT device (Speed-Scan) produced by General Electric, which has been used by Volkswagen in Germany for actual castings. detected. However, looking at the domestic die casting industry, using real-time CT technology to control the quality of castings is a severe challenge at the operational level. The biggest limitation is cost, because the cost of CT test equipment is very high and used for production. The production line usually requires a large amount of CT test equipment, which is beyond the capabilities of most domestic companies. With the continuous development of the industry and the continuous improvement of casting quality requirements, the use of CT technology to detect the internal quality of castings in real time will become a general requirement of OEMs for suppliers in the future. .


3. Process feedback and adjustment

Under the premise of detecting castings through CT and obtaining three-dimensional solid data, we assume that there is an algorithm that can analyze the data very effectively and give all the information about the internal defects of the casting, including type, size and distribution, etc. Then we can use this Information to adjust and correct the production process itself, and finally obtain qualified castings without excessive defects. The process of obtaining casting information and modifying the process is called process feedback and adjustment process. Of course, we cannot complete this process based on a piece of casting information alone. The most normal situation is to obtain a large amount of casting information, and solve the casting defects through statistical analysis and process-related methods.

The next question is, even if we obtain a lot of defect distribution information inside the casting, how to avoid unqualified defects by adjusting the process parameters? The most powerful analysis tool available is computer numerical simulation, which is well known to our computer-aided engineering (CAE) technology.

Using computer simulation technology, we can realize local virtual production. Especially for die-casting, we can directly numerically simulate the filling and solidification process by studying the velocity, pressure, flow pattern and splash of the fluid filling cavity, so as to determine whether there is gas in the filling process. By calculating the temperature changes of the casting and the mold under different cycle conditions of the die casting, determine and study the potential hot joints, the casting defects (shrinkage, shrinkage) and the thermal equilibrium behavior of the die casting. Through this numerical simulation technology, on the basis of certain analysis conditions, we can judge and avoid the internal defects of the casting to a large extent, improve the performance of the casting, greatly increase the production efficiency, and realize the process feedback and correction we discussed earlier. . purpose.

We put the whole process together: using digital technology (CT) to detect the three-dimensional defect data of the product in real time. If the product is unqualified, the data will be transmitted to the CAE analysis center, and the simulation technology will be used to analyze and generate the solution to the defect problem, and the solution feedback information will be sent to the production and process front-end for execution and re-acquire the product. The product continues to be digitally inspected and 3D defect data is obtained. If the product is qualified, the iteration ends, otherwise it continues.

 

Master the core digital technology

It can be seen that CAE analysis plays a key role in this process, and the effectiveness of the proposed solution will have an impact on the efficiency of the entire process. In fact, whether you can master the core of CAE technology and whether you can apply numerical simulation technology in actual production can measure the technical capabilities of die-casting companies to a large extent, because digital technology is indispensable to the way of business, the sooner you Master the core of digital technology on this road, the more you can stand out in future corporate competition.

Therefore, if digital inspection technology and CAE analysis technology are well applied to existing die-casting enterprises, we can see a complete and typical digital factory scene. Among them, digital detection technology realizes the digitization of physical entities, and CAE analysis technology converts the digital information obtained through detection into a problem solution based on virtual production. In this process, digital detection is actually a completely automated process, and CAE analysis still requires manual participation. If CAE analysis can be integrated into an algorithm and fully automated, then this is the prototype of the future smart digital factory.

 


Jiaxing Yunhe Trading Co., Ltd. specializes in producing aluminum alloy die-casting, zinc alloy die-casting and other non-ferrous metal die-casting products. Our products mainly cover automobiles, motorcycles, auto parts, luggage, medical equipment (wheelchairs), lights, LEDs, locks, connectors, elbows, strollers, belt buckles, and   Hardware fitting   . With various mold manufacturing equipment and product surface brightening treatment, we are committed to producing various molds. Is a professional manufacturer and supplier of  Hardware fitting in China. Welcome to buy: https://www.xinxinmetal.com/

 

221 Views