Casting process

With the progress of science and technology and the vigorous development of the foundry industry, different casting methods have different mould for content.

In the most widely used sand mold casting, for example, mold preparation including molding materials preparation and molding core making two categories of work. The model used in sand casting core making all kinds of raw materials, such as casting sand, sand binder, and other accessories, and a mixture of sand, their core sand, coating etc are collectively referred to as molding material molding materials prepared by the nature of the task is in accordance with the requirements of the castings, metal, choose appropriate raw sand, binder and auxiliary materials, and then according to certain proportion mixed them into has certain properties of the sand and core sand. Commonly used sand mixing equipment have grinding wheel sand mixer, counter-current type sand mixing machine and blade groove type sand mixer. The latter is designed for mixing chemical process and the design of continuous mixing, fast.

Modelling of core making is according to casting process requirements, in determining the good modelling method, molding materials ready. On the basis of the The accuracy of castings and economic effect of all the production process, mainly depends on the procedure. In many modern foundry, core making modelling has realized mechanization and automation. Commonly used modelling sand core making equipment have high, medium and low pressure molding machine, sand slinger, no cases of shoot-squeeze molding machine, shoot core machine, cold and hot core box machine and so on.

Casting after pouring cooling of the casting to retrieve, sprue and riser, metal burrs, feng and die line, also adhesion of sand mold casting casting sand, so must go through cleaning process. For devices of this kind of job have a polishing machine, shot blasting machine, casting riser cutting machine, etc. Sand mold casting sand cleaning is a process with the poor working conditions, so the choice modelling method, should be considered as far as possible to create convenient conditions for shakeout to clear. Some castings due to special requirements, but also the casting post-processing, such as heat treatment, shaping, anti-rust treatment, rough machining, etc.

Industry characteristics

1.Casting blank forming methods is more economic, more can show it to complicated shape parts of the economy.
Such as automobile engine cylinder block and cylinder head, Marine propeller and exquisite works of art, etc. Some difficult to cutting the parts, such as gas turbine nickel-based alloy parts forming without casting method.

2.The size and weight of casting parts to adapt to the range is very wide, almost unlimited types metal.
Parts in the general mechanical properties, but also has wear-resisting, corrosion resistant, shock absorption, such as comprehensive performance, is other metal forming methods, such as forging, rolling, welding, punching, etc. So using produced by the method of casting blank parts in the machine manufacturing industry, on the number and tonnage so far is still the most.

3.Casting production often want to use the material with various metals, coke, wood, plastics, gas and liquid fuels, molding materials, etc.
Smelting metal required equipment have to use all kinds of the stove, with all kinds of sand mixer, sand mixing with various molding machine molding core making, core making machine, have clean castings with shakeout machine, shot blasting machine, etc. And for special casting machinery and equipment and many transportation and materials handling equipment.

4.Casting production have different characteristics with other technology, wide adaptability, more materials and equipment will be needed, pollute the environment.
Casting production will produce dust, harmful gases, and noise pollution to the environment, compared with other mechanical manufacturing process is more serious, need to take measures to control it.

5.For casting engineers and mechanical structure design engineer, heat treatment is a very meaningful and very high value to improve the method of material quality, through heat treatment can change or influence the organization and properties of cast iron, and can obtain higher strength, hardness, and improve the wear resistance and so on.

Because purpose is different, the kinds of heat treatment is very much, basically can be divided into two main categories：
(1). The first category is the organization structure will not change or through heat treatment and should not be changed.

(2). The second is the basic organizational structure change.
The first heat treatment procedure, is mainly used to eliminate the internal stress, and the internal stress in the casting process due to different cooling conditions and conditions. Organization, strength and other mechanical properties, no obvious changes due to heat treatment.
For the second heat treatment, al qaeda has had the obvious change, can be roughly divided into five categories:

Softening annealing:
(1) the purpose is to decompose carbide, its hardness is reduced, and improve the processing performance, for the spherical graphite cast iron, its aim is to obtain iron group has a very high fertility.

(2) the normalization processing: mainly used to improve or make completely is a wave to cast iron products for mechanical properties of uniform distribution.

(3) hardening: mainly in order to obtain a higher hardness and abrasion strength, at the same time to the surface of the high wear-resisting properties.

(4) surface hardening treatment: mainly for surface hardening layer, at the same time, get very high surface wear-resisting properties.

(5) precipitation hardening treatment: mainly in order to obtain high strength and elongation is not so drastic change.

Industry trends

Casting product development trend is the requirement of castings have better comprehensive performance, higher accuracy, less allowance and more bright and clean surface. In addition, the requirements of energy saving and society calls for recovery of the natural environment is becoming more and more high. To meet these requirements, a new casting alloy will be development, smelting new technology and new equipment will appear accordingly.

Foundry production of mechanization degree of automation in improving at the same time, the more the flexible production direction, to broaden the adaptability of different production batch and many varieties. To save energy and the new technology will get the priority to the development of raw materials, produce or not produce less pollution of the new technology of new equipment will be the first to be taken seriously. Quality control technology in the process of testing and nondestructive flaw detection, determination of stress, there will be a new development.

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