In order to achieve layer by layer solidification or avoid shrinkage holes, chill is often used in castings in Guangdong mechanical processing plant. In essence, cold iron is a large heat source. At any time, it is impossible to provide a chill for a part of a heavy casting. The chill is in close contact with it, as shown in Figure 5.29. As a result, the chill absorbs more heat rapidly from the thick and heavy parts, making the cooling rate equal to that of the thin-walled parts. Thus, the formation of shrinkage cavity is prevented. However, the use of cold iron means higher cooling rate, it will also tend to form pitting in the cross area with cold iron, if this area needs further machining, it will lead to problems.

Smelting operation
The preparation stage of molten metal in Guangdong mechanical processing plant is usually called smelting, which is usually completed in a specially designed workshop area, and then the molten metal is transferred to the pouring area full of mold. After molding, melting becomes the main factor to control the casting quality. There are many effective methods to melt casting alloy, such as pit furnace, open furnace, rotary furnace, cupola, etc. the choice of furnace depends on the wide application of various types of cupola, mainly because of the low original cost and low melting cost.
clear
The cleaning of Guangdong mechanical processing plant involves all the processes to remove the sand, scales and the excess metal on the casting. The casting is separated from the mold and then transported to the cleaning station to clean the sintered sand and scales to improve the surface morphology of the casting. Excess metal is removed in the form of fins, threads, parting line fins and gates. The casting can be further formed by welding or other steps, and then the defects and quality of the casting can be detected.
Other processes
Before transportation, further processes such as heat treatment, surface treatment, additional testing, or machining should also be operated according to the needs of consumers.