Casting process flow
With the progress of science and technology and the vigorous development of foundry industry, different casting methods have different mold preparation contents. Taking sand casting, which is widely used, as an example, mold preparation includes molding material preparation, molding and core making. Various raw materials used for molding and core making in sand casting, such as casting raw sand, molding sand binder and other auxiliary materials, as well as molding sand, core sand and coating prepared from them, are collectively referred to as molding materials. The task of molding material preparation is to select appropriate raw sand, binder and auxiliary materials according to the requirements of castings and the properties of metals, and then mix them into molding sand and core sand with certain properties according to a certain proportion. Common sand mixing equipment include roller type sand mixer, counter current type sand mixer and continuous type sand mixer. The latter is specially designed for mixing chemical self hardening sand, with continuous mixing and fast sand mixing speed.
Molding and core making are carried out on the basis of determining molding methods and preparing molding materials according to casting process requirements. The accuracy of castings and the economic effect of the whole production process mainly depend on this process. In many modern foundry workshops, molding and core making have been mechanized or automated. Common sand molding and core making equipment include high, medium and low pressure molding machines, air impact molding machines, box less injection molding machines, cold core box core making machines, hot core box core making machines, coated sand core making machines, etc.
After the casting is taken out from the casting mold cooled by pouring, there are gates, risers, metal burrs and drapes. Sand is also adhered to the sand casting, so it must be cleaned. The equipment for this kind of work includes polishing machine, shot blasting machine, gating and riser cutting machine, etc. Sand falling cleaning of sand castings is a process with poor labor conditions, so when choosing molding methods, we should try to create convenient conditions for sand falling cleaning. Due to special requirements, some castings need post-treatment, such as heat treatment, shaping, rust prevention treatment, rough machining, etc.
The casting process can be divided into three basic parts, namely, metal preparation, mold preparation and casting treatment. Cast metal refers to the metal materials used for casting in casting production. It is an alloy composed of one metal element as the main component and other metal or non-metal elements. It is conventionally called cast alloy, mainly including cast iron, cast steel and cast nonferrous alloy.
After the casting is taken out from the casting mold cooled by pouring, there are gates, risers and metal burrs. Sand is still adhered to the sand casting, so it must be cleaned. The equipment for this work includes shot blasting machine, gate and riser cutting machine, etc. Sand falling cleaning of sand castings is a process with poor labor conditions, so when choosing molding methods, we should try to create convenient conditions for sand falling cleaning. Due to special requirements, some castings need post-treatment, such as heat treatment, shaping, rust prevention treatment, rough machining, etc.
Casting is a relatively economical method of blank forming, and it can show its economy for complex parts. Such as the cylinder block and cylinder head of automobile engines, ship propellers and exquisite works of art. Some parts that are difficult to cut, such as nickel base alloy parts of gas turbines, cannot be formed without casting.
In addition, the size and weight of cast parts can be adapted to a wide range, and the type of metal is almost unlimited; The parts not only have general mechanical properties, but also have comprehensive properties such as wear resistance, corrosion resistance and shock absorption, which can not be achieved by other metal forming methods such as forging, rolling, welding and punching. Therefore, in the machine manufacturing industry, the number and tonnage of rough parts produced by casting is still the largest.
