With the progress of science and technology and the flourishing development of the foundry industry, different casting methods have different content of mould preparation. Taking the most widely used sand casting as an example, the casting preparation includes two major tasks: the preparation and molding of the molding materials and the core making. Sand casting used in various raw materials molding, core making, such as casting sand, sand binder and other materials, and the preparation of sand, sand, paint etc. are collectively called the plastic materials, other materials preparation task is in accordance with the requirement of the casting, metal properties, selection of sand and binder and then according to a certain proportion of materials, mixing them into the sand and core sand with certain properties. The common sand mixing equipment includes roller type sand mixer, countercurrent mixer and continuous sand mixer. The latter is designed for mixed chemical self - hardened sand, which is mixed continuously, and the speed of mixing is fast.
Molding and core making are based on the requirements of the casting process, on the basis of determining the molding method and preparing the molding materials. The precision of the casting and the economic effect of the whole production process are mainly determined by this process. In many modern foundry workshops, the molding and the core making have been mechanized or automated. Other commonly used sand core making equipment with high, medium and low pressure molding machine, air impact molding machine, injection molding machine, box, cold box core making machine and hot box core making machine, coated sand core making machine etc..
The casting process can be divided into three basic parts, namely, the preparation of the cast metal, the preparation of the mold and the treatment of the casting. Casting metal refers to casting pouring casting metal material used in the production, it is a kind of metal elements as the main ingredient, and adding other metal or nonmetal elements and the composition of the alloy, traditionally known as the main cast alloy, cast iron, cast steel and cast nonferrous alloys.
Casting is a more economical blank forming method, and it is more economical for the parts with complex shapes. Such as the cylinder and cylinder head of an automobile engine, ship propeller and fine art, etc. Some parts that are hard to be cut, such as the nickel based alloy parts of the steam turbine, can not be formed without the casting.
In addition, casting parts of the size and weight of the range is very wide, metal species almost unlimited; in parts of the mechanical properties at the same time, also has the wear resistance and corrosion resistance, shock absorption performance, other metal forming methods such as forging, rolling, welding, punching etc. to do. Therefore, the blank parts produced by casting methods in the machine manufacturing industry are still the largest in quantity and tonnage.
The casting is removed from the casting mold, and there are gates, risers and metal burrs. The sand casting castings are still attached to the sand, so the cleaning process must be done. The equipment for this kind of work is a shot blasting machine, a gate riser cutting machine and so on. Sand casting and sand cleaning is a working process with poor working conditions. Therefore, when selecting the modeling method, we should try to consider creating convenient conditions for cleaning up. Some castings have to be treated after casting for special requirements, such as heat treatment, plastic, rust prevention and rough processing.
The materials used in the foundry production are all kinds of metal, coke, wood, plastic, gas and liquid fuel, molding materials and so on. The equipment needed includes all kinds of furnaces for smelting metals, all kinds of sand mixing machines for sand mixing, molding machines for core making, core making machines, cleaning machines for sand castings, shot blasting machines, etc. There are also machines and equipment for special casting, as well as a lot of transportation and material handling equipment.
The trend of the development of the foundry product is to require the castings to have better comprehensive properties, higher precision, less allowance and a more smooth surface. In addition, the demand for energy saving and the voice of society to restore the natural environment are also increasing. In order to meet these requirements, new casting alloys will be developed, new smelting process and new equipment will appear accordingly.
The degree of mechanization and automation of foundry production is improving continuously, and more flexible production will be developed to expand adaptability to different batch and multi variety production. New technologies for saving energy and raw materials will be developed first, and new technology and new equipment with little or no pollution will be paid attention to first. The quality control technology will have a new development in the detection of various processes, nondestructive testing and stress measurement.
The foundry production has different features from other processes, mainly with wide adaptability, more materials and equipment, and polluted environment. Casting production produces dust, harmful gas and noise pollution to the environment, which is more serious than other mechanical manufacturing processes, and measures need to be taken to control it.
