Iron castings are widely used in various mechanical equipment, construction, metallurgy, agricultural machinery, national defense industry and other fields. In the machinery manufacturing industry, the proportion of iron castings is about 40-85% of the mechanical weight. There are many kinds of iron castings, and their weight varies from light to heavy; According to the current casting technology, the thickness dimension of the casting can be w controlled within 2mm-500mm.
The reason why iron castings are so widely used is that they have the following characteristics:
1) Cast iron soldering liquid has relatively good fluidity and strong filling ability. It can cast iron castings with complex shape and large change in thickness and size, such as cylinder block, machine tool base, flywheel, hydraulic valve body, etc.
2) The shrinkage of gray cast iron during solidification is small. During shallow injection, a relatively complete and dense casting can be obtained even without riser, and its performance is relatively stable.
3) Compared with other alloy materials, cast iron has low melting point, common smelting raw materials and simple method. Compared with forging, welding and other material processing processes, the cost of casting is very low.
4) Iron castings have good shock absorption. Due to the existence of graphite in the cast iron matrix, the relationship between the metal matrix is separated. When the gray castis running at high speed, it can well absorb vibration. Therefore, when iron castings are used in the base of large machines, they will have a good shock absorption effect.
5) Iron castings have good machinability. Because of the existence of skillful ink in cast iron, cutting is easy to break, and can form a natural lubricant. At the same time, the notch sensitivity of cast iron can be reduced.
6) After scrapping, the iron castings can be returned to the furnace for recasting after cleaning, with good reusability.