Metal casting is a relatively economical blank forming method, which can show its economic performance for the complicated shape parts. such as automobile engine cylinder and cylinder head, ship propeller and exquisite artwork. Some parts that are difficult to cut, such as the nickel base alloy parts of a steam turbine, Metal Casting are not formed without a metal casting method.
In addition, the metal casting parts size and weight of the adaptation range is very wide, metal types are almost unlimited; the parts in general mechanical properties at the same time, but also wear-resistant, corrosion-resistant, shock absorption and other comprehensive properties, Metal Casting is other metal forming methods such as forging, rolling, welding, punching and so can not be done. Therefore, the metal casting method in the machine manufacturing of rough parts, in both quantity and tonnage is still the most.
Metal casting production often used materials have a variety of metals, electricity, coke, wood, plastics, gas and liquid fuels, modelling materials. The required equipment has a variety of smelting metal furnace, a variety of sand mixing machine, there is a variety of modelling molding machine, core-making machine, Metal Casting have to clean up the casting sand machine, shot blasting machine. There are also machines and equipment for special metal casting and many transportation and material handling equipment.
Metal casting production has different characteristics with other processes, mainly adaptable, need materials and equipment, pollution of the environment. Metal casting will produce dust, harmful gases and noise pollution to the environment, more serious than other mechanical manufacturing processes, Metal Casting need to take measures to control.
For metal casting engineers and mechanical structural design engineers, heat treatment is a very meaningful, and very valuable method to improve the quality of materials, by heat treatment can change or affect the microstructure and properties of cast iron, but also to obtain higher strength, hardness, Metal Casting and improve their abrasion resistance and so on.
Because of the different purposes, the types of heat treatment are very many, Metal Casting basically can be divided into two categories, the first is that the structure will not undergo heat treatment and change or should not occur, the second is the basic structure of the change. The first heat treatment procedure is mainly used to eliminate the internal stress, which is caused by the different cooling condition and condition in the metal casting process. Organization, strength and other mechanical properties, not due to heat treatment and change significantly.
Forming characteristics of metal casting: the thermal conductivity of metal-type materials is larger than that of sand-type materials, and there is no permeability and no compromise. Damage form: ① external crack A, the stress caused by the temperature change to the mold tensile strength when the crack (preheating metal type) b, unreasonable structure c, defect of sand hole inclusions D, blank exists casting stress D, low stiffness ② internal crack A, fatigue stress B, alternating thermal stress ③ deformation, multiple pouring, thin wall, high temperature, The pouring time is long (time is fixed by gating system) ④ burns, the wall thick place temperature is too high ⑤ friction. The way to improve the life of metal type A, heat treatment to reduce stress B, correct selection to ensure stiffness C, reasonable wall thickness and structure to prevent stress concentration D, gating system design should be reasonable e, Metal Casting coating performance and spraying technology. The role of paint: A, the protection of metal type B, adjust the casting parts in the metal type of cooling speed C, improve the quality of the casting surface D, Metal Casting appropriate to improve the metal type of exhaust conditions. Coating requirements: A, viscosity of uniform b, fire resistance C, small d, no chemical reaction e, easy to clear