Selection of blanks for machining parts in CNC machining

CNC machining Before the development of the machining rules for parts, it is necessary to select the types of blanks before the parts are processed and their different manufacturing methods. Since the number of processes, material consumption, and labor consumption of CNC machining parts are largely related to the selection of blanks, the correct selection of blanks has great technical and economic significance.

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 The types of commonly used CNC machining parts are: castings, forgings, profiles, welded parts, stampings, etc., and the same kind of blanks may have different manufacturing methods. The choice of blank should take into account the size of the production scale, which largely determines the economics of using a certain blank manufacturing method. If the production scale is large, the high-precision and high-productivity blank manufacturing method can be adopted, which not only saves raw materials but also significantly reduces the amount of machining labor. Moreover, the high precision of the blank can simplify the process and process equipment, and reduce the product. total cost. In fact, the selection of CNC machining blanks should consider the following points:

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1. The shape and size of the workpiece structure. For example, blanks with complex shapes and thin walls are generally not castable in metal form; blanks with larger sizes are often not used for die forging, die casting and precision casting. For example, some small parts with special shapes are difficult to machine, and more sophisticated blank manufacturing methods, such as die casting and investment casting, are often used to minimize the amount of machining.

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2, the mechanical properties of the parts. The same material uses different blank manufacturing methods, and its mechanical properties tend to be different. For example, a metal cast blank has a higher strength than a sand cast, a centrifugal cast and a pressure cast blank, and its strength is higher than that of a metal cast blank. Forgings with high strength requirements are often used, and ductile iron parts are sometimes used.

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3. The possibility and economy should be considered from the existing equipment and technical level of the factory. Consideration should also be given to the possibility of using new processes, new technologies and new materials such as precision casting, precision forging, cold rolling, cold extrusion, powder metallurgy and engineering plastics. With these blank manufacturing methods, the amount of machining can be greatly reduced, and sometimes the numerical control machining can be omitted, and the economic effect is very remarkable.cnc machining.