Due to the advantages of accurate size and bright surface of aluminum casting, it can be directly used after machining. Therefore, it not only improves the metal application rate, but also reduces a lot of processing equipment and casting price. Combined die casting and other metal or nonmetal materials are used to save assembly time and metal. Although aluminum casting has many advantages, it also has some defects to be treated. For example: due to the high filling speed of liquid metal in die casting, the state is unstable, so the common die casting method is adopted. It is difficult to die-casting for the castings with complex concave. High melting point alloy: such as copper, ferrous metal, die casting die life is low; It is not suitable for small batch consumption. The main reason is that the cost of aluminum casting is high, the consumption efficiency of die casting machine is high, and small batch consumption is uneconomic.
The density of cast aluminum is lower than that of cast iron and cast steel, but the specific strength is higher. Therefore, under the same load condition, aluminum alloy casting can reduce the weight of structure, so it is widely used in aviation industry, power machinery and transportation machinery manufacturing. Aluminum alloy has good appearance luster and good corrosion resistance in the atmosphere and fresh water, so it is widely used in the manufacture of civil utensils. Pure aluminum has good corrosion resistance in oxidizing acid medium such as nitric acid and acetic acid, so aluminum castings are also useful in chemical industry. Pure aluminum and aluminum alloy have good thermal conductivity. Heat exchange installation used in chemical industry consumption, and parts requiring good thermal conductivity in power machinery, such as cylinder head and piston of internal combustion engine, are also suitable for manufacturing with aluminum alloy.
The cast aluminum parts have good casting properties. Because of the low melting point (the melting point of pure aluminum is 660.230c, and the pouring temperature of aluminum alloy is about 730-750oc), metal mold and pressure casting can be widely used to improve the internal quality, dimensional accuracy, appearance brightness level and consumption efficiency of castings. Due to the high latent heat of solidification, the solidification time of aluminum liquid is much longer than that of cast steel and cast iron under the same weight condition, and it has good mobility, which is conducive to casting thin-walled and complex castings.
Aluminum casting has many advantages, which makes it become the development direction of the casting industry and one of the favorite casting products for purchasing customers. In the future, with the progress of aluminum casting technology, it will show its style on the big stage.
The heat treatment process of aluminum castings consists of heating, heat preservation and cooling. The whole process can be described by several parameters such as heating rate, heating temperature, holding time, cooling rate and heat treatment cycle. In each heat treatment process specification, temperature is a very important content. If the temperature measurement is not accurate, the heat treatment process specification can not be carried out correctly, resulting in the decline of aluminum casting quality or even scrap. The measurement and control of temperature is the key of heat treatment process, and also the key factor affecting the deformation. The influence of cooling process on the deformation of aluminum castings after quenching is also a very important deformation reason. During the cooling process of metal after heat treatment, the thin part always cools faster than the thick part. In the case of meeting the actual production needs, the gap between the thickness of the workpiece should be reduced as far as possible, and the cross section of the parts should be uniform to reduce the distortion and cracking tendency of the transition zone due to stress concentration. In order to improve the qualified rate of deformation after quenching, reverse deformation and pre expanding hole at shrinkage end are applied according to the deformation law of aluminum casting after heat treatment.
How to store aluminum castings correctly?
1. When storing sand cast aluminum castings, they need to be placed in a ventilated, dry and non corrosive storage environment; Strictly prevent the rain from getting wet.
2. Sand cast aluminum castings must not contact with other chemical elements. When sand cast aluminum castings contact with other chemical elements, chemical elements will react with sand cast aluminum castings, which will cause damage to sand cast aluminum castings.
3. Each sand cast aluminum casting has its own special shape. When placing the zinc alloy sand cast aluminum casting products, we should customize the special suction tray according to the shape of each sand cast aluminum die casting products, so as to ensure that the sand cast aluminum casting parts are placed in a specific position, so that the sand cast aluminum casting parts are intact and will not have any other changes.
4. Zinc is a kind of active metal. When the temperature reaches the corresponding conditions, it is easy to be oxidized. Therefore, when we store zinc alloy sand casting aluminum products, we should pay attention to the temperature and avoid direct sunlight.
5. If the raw alloy ingot of casting zinc alloy products is affected with moisture, it should be dried before adding, so as to avoid "blasting" injury or damage to equipment during melting.