The basis for selecting blanks of machining parts during CNC machining

CNC machining Before formulating part machining process procedures, the types of blanks before parts processing and their different manufacturing methods must be selected. Since the number of processes, material consumption, processing labor, etc. of CNC machining parts are largely related to the selection of blanks, the correct choice of blanks has great technical and economic significance.

Commonly used CNC machining parts blanks include: castings, forgings, moldings, welded parts, stamping parts, etc., and the same type of blanks may have different manufacturing methods. The choice of blanks should consider the size of the production scale, which largely determines the economics of adopting some method of blank manufacturing. If the production scale is large, high-precision and high-productivity blank manufacturing methods can be used. In this way, although the investment is high at one time, the cost of sharing equally to each blank will be less. Moreover, since the productivity of the blank manufacturing method with higher accuracy is generally higher, it not only saves raw materials but also significantly reduces the amount of mechanical processing labor. Moreover, the high blank precision can also simplify processes and process equipment and reduce the total cost of the product. In fact, when choosing a blank CNC machining part, the following points should be considered:

1. The shape and size of the workpiece structure. For example, blanks with complex shapes and thin walls cannot be cast in metal shapes; blanks with larger sizes often cannot be die-forging, die-casting and fine-casting. For example, some small parts with special appearance, due to the difficulty of machining, they often use more precise blank manufacturing methods, such as die casting, investment casting, etc. to minimize the amount of machining.

2. Requirements for the mechanical properties of parts. The same material adopts different blank manufacturing methods, and its mechanical properties are often different. For example, a metal-cast blank has a higher strength than a sand-cast blank, a centrifugal-cast and pressure-cast blank, and a higher strength than a metal-cast blank. Parts with high strength requirements mostly use forged parts, and sometimes ductile iron can be used.

3. The possibility and economy should be considered based on the existing equipment and technical level of our factory. The possibility of utilizing new processes, new technologies and new materials, such as fine casting, fine forging, cold rolling, cold extrusion, powder metallurgy and engineering plastics, etc. should also be considered. After using these blank manufacturing methods, the amount of machining can be greatly reduced, and sometimes no longer machining can be performed, and the economic effect is very significant.