trait
High pressure and high speed mold filling casting are two characteristics of die casting. Its common injection specific pressure ranges from several thousand to tens of thousands of kPa, even as high as 2× 105kPa. The filling speed is about 10~50m/s, and sometimes even more than100m/s. The filling time is very short, generally within the range of 0.01~ 0.2s. Compared with other casting methods, die casting has the following three advantages:
Advantages:
1. Good product quality
The dimensional accuracy of castings is high, generally equivalent to 6~7 grades, and even up to 4 grades; Good surface finish, generally equivalent to 5~8 grades; The strength and hardness are higher, the strength is generally 25~30% higher than that of sand casting, but the elongation is reduced by about 70%; Stable size and good interchangeability; Die-casting thin-walled complex castings. For example, the minimum wall thickness of zinc alloy die casting can reach 0.3mm； at present; Aluminum alloy castings can reach 0.5mm；; The minimum casting aperture is 0.7mm；; The minimum spacing is 0.75mm.
2. High production efficiency
The productivity of the machine is high, for example, the domestic J Ⅲ 3 horizontal cold air die casting machine can die cast 600 ~ 700 times every eight hours on average, and the small hot chamber die casting machine can die cast 3000~7000 times every eight hours on average; Die-casting type has a long service life, and a pair of die-casting type and die-casting clock alloys can have a service life of hundreds of thousands or even millions of times; It is easy to realize mechanization and automation.
3. Good economic effect
Due to the advantages of accurate die-casting size and smooth surface. Generally, it is used directly without mechanical processing, or the processing amount is very small, which not only improves the metal utilization rate, but also reduces a lot of processing equipment and working hours; The casting price is easy; Combined die casting can be used for other metal or nonmetal materials. Save assembly time and metal.
Although die casting has many advantages, there are also some shortcomings to be solved.
disadvantaged
For example:
1). Due to the fast filling speed and unstable flow pattern of liquid metal during die casting, the castings are prone to produce blowholes by ordinary die casting methods and cannot be heat treated;
2) It is difficult to die-cast complex concave castings;
3) High melting point alloys (such as copper and ferrous metals) have short die-casting life;
4) Not suitable for small batch production. The main reasons are high manufacturing cost of die casting, high production efficiency of die casting machine and uneconomical small batch production.
Application scope and development trend of die casting
Die casting is one of the most advanced metal forming methods and an effective way to achieve less chips and no chips. It is widely used and develops rapidly. The size and weight of castings depend on the power of die casting machine. Due to the increasing power of die casting machine, the shape and size of castings can range from a few millimeters to1~ 2 m; The weight ranges from a few grams to dozens of kilograms. Foreign aluminum castings with a diameter of 2m and a weight of 50kg can be die-cast.
Die-casting parts are no longer limited to automobile industry and instrument industry, but gradually extended to other industrial sectors, such as agricultural machinery, machine tool industry, electronics industry, national defense industry, computers, medical devices, watches, cameras and daily hardware. , specifically: automobile parts, furniture parts, bathroom parts (bathroom), lighting parts, toys, planers, tie clips, electrical and electronic parts, belt buckles. In the aspect of die casting technology, new technologies such as vacuum die casting, oxygen die casting, precision rapid dense die casting and the application of soluble cores have emerged.
It will play a very good role in promoting the die casting industry in China.